feat: move EL0 stack to virtual space

.env.example

@@ -1,6 +1,6 @@
 KERNEL_NAME=kernel8.img
 BUILD_PATH=target/aarch64-unknown-none/release
-BINARY_NAME=nova
+BINARY_NAME=BINARY_NAME
 TFTP_PATH=/srv/tftp
 REMOTE_USER=TFTP_HOST_USER
 REMOTE_HOST=TFTP_HOST_IP

.gitignore

@@ -5,9 +5,3 @@ sd.img
 settings.json
 .DS_Store
 .venv
-.nvimlog
-__pycache__
-.pytest_cache
-
-build/
-

.vscode/launch.json

@@ -3,7 +3,7 @@
   "compounds": [
     {
       "name": "Run QEMU + Attach LLDB",
-      "configurations": ["LLDB"],
+      "configurations": ["Attach LLDB"],
       "preLaunchTask": "Run QEMU"
     }
   ],
@@ -58,22 +58,13 @@
       ],
       "preLaunchTask": "Run QEMU wo window"
     },
-    {
-      "name": "LLDB",
-      "type": "lldb",
-      "request": "attach",
-      "program": "${workspaceFolder}/target/aarch64-unknown-none/debug/nova",
-      "preLaunchTask": "Run QEMU",
-      "stopOnEntry": true,
-      "processCreateCommands": ["gdb-remote localhost:1234"]
-    },
 
     {
-      "name": "NVIM LLDB",
+      "name": "Attach LLDB",
-      "type": "codelldb",
+      "type": "lldb",
       "request": "attach",
+      "debugServer": 1234,
       "program": "${workspaceFolder}/target/aarch64-unknown-none/debug/nova",
-      "preLaunchTask": "Run QEMU",
       "stopOnEntry": true,
       "processCreateCommands": ["gdb-remote localhost:1234"]
     }

Cargo.lock

@@ -40,31 +40,14 @@ version = "0.2.15"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "f9fbbcab51052fe104eb5e5d351cf728d30a5be1fe14d9be8a3b097481fb97de"
 
-[[package]]
-name = "lock_api"
-version = "0.4.14"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "224399e74b87b5f3557511d98dff8b14089b3dadafcab6bb93eab67d3aace965"
-dependencies = [
- "scopeguard",
-]
-
-[[package]]
-name = "log"
-version = "0.4.29"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5e5032e24019045c762d3c0f28f5b6b8bbf38563a65908389bf7978758920897"
-
 [[package]]
 name = "nova"
 version = "0.1.0"
 dependencies = [
  "heap",
  "libm",
- "log",
  "nova_error",
  "paste",
- "spin",
 ]
 
 [[package]]
@@ -139,21 +122,6 @@ dependencies = [
  "getrandom",
 ]
 
-[[package]]
-name = "scopeguard"
-version = "1.2.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "94143f37725109f92c262ed2cf5e59bce7498c01bcc1502d7b9afe439a4e9f49"
-
-[[package]]
-name = "spin"
-version = "0.10.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d5fe4ccb98d9c292d56fec89a5e07da7fc4cf0dc11e156b41793132775d3e591"
-dependencies = [
- "lock_api",
-]
-
 [[package]]
 name = "syn"
 version = "2.0.111"

Cargo.toml

@@ -17,8 +17,6 @@ libm = "0.2.15"
 heap = {path = "workspace/heap"}
 nova_error = {path = "workspace/nova_error"}
 paste = "1.0.15"
-log = "0.4.29"
-spin = "0.10.0"
 
 [workspace]
 

LICENSE

@@ -1,26 +0,0 @@
-MIT NON-AI License
-
-Copyright (c) 2026, Alexander Neuhäuser
-
-Permission is hereby granted, free of charge, to any person obtaining a copy of the software and associated documentation files (the "Software"),
-to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense,
-and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions.
-
-The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
-
-In addition, the following restrictions apply:
-
-1. The Software and any modifications made to it may not be used for the purpose of training or improving machine learning algorithms,
-   including but not limited to artificial intelligence, natural language processing, or data mining. This condition applies to any derivatives,
-   modifications, or updates based on the Software code. Any usage of the Software in an AI-training dataset is considered a breach of this License.
-
-2. The Software may not be included in any dataset used for training or improving machine learning algorithms,
-   including but not limited to artificial intelligence, natural language processing, or data mining.
-
-3. Any person or organization found to be in violation of these restrictions will be subject to legal action and may be held liable
-   for any damages resulting from such use.
-
-THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
-DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE
-OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

README.md

@@ -1,120 +1,23 @@
 # NovaOS
 
-![NovaOS banner](docs/banner.png)
+NovaOS is a expository project where I build a kernel from scratch for a Raspberry PI 3 B+.
 
-NovaOS is a hobby operating system kernel written in Rust for the Raspberry Pi 3 B+.
+[Technical write-up](https://leafnova.net/projects/pi3_kernel/)
-It is built as a learning project for low-level systems programming, bare-metal boot flow, and kernel development.
 
-## At A Glance
+## Features
 
-NovaOS currently includes:
+- Delay and sleep ✓
-
+- UART ✓
-- UART initialization and logging
+- Switching ELs ✓
-- Delay and sleep primitives
+- GPIOs ✓
-- Exception level transitions across EL2, EL1, and EL0
+- GPIO Interrupts ✓
-- GPIO control and interrupt handling
+- Communicate with peripherals via mailboxes ✓
-- Peripheral mailbox communication
+- Frame Buffer ✓
-- Framebuffer drawing primitives
+- Heap Memory allocation ✓
-- Heap memory allocation
+- MMU ✓
-- MMU initialization and translation table setup
+- SVC instructions
-
+- Kernel Independent Applications
-Work in progress:
+- Multi Core
-
+- Dynamic clock speed
-- SVC instruction handling
+- Multiprocessing
-- Basic UART console improvements
+- Basic Terminal over UART
-- Multi-application management
-
-Planned next:
-
-- Multi-core support
-- Dynamic clock speed management
-- Kernel-independent applications
-- Multiprocessing improvements
-
-## Project Structure
-
-- `src/` - kernel source, architecture code, peripherals, interrupts, and runtime
-- `workspace/` - supporting crates such as `heap` and `nova_error`
-- `tools/` - build, simulation, SD image generation, and deployment scripts
-- `firmware_files/` - Raspberry Pi firmware files copied to SD or TFTP
-- `link.ld` - linker script for the kernel image
-
-## Requirements
-
-You will need:
-
-- Rust nightly toolchain (`rust-toolchain.toml` pins `nightly`)
-- Rust target `aarch64-unknown-none`
-- `llvm-objcopy` for generating `kernel8.img`
-- `qemu-system-aarch64` for emulation
-- `mtools` (`mformat`, `mcopy`) for SD image generation
-
-Install the Rust target if needed:
-
-```bash
-rustup target add aarch64-unknown-none
-```
-
-## Build
-
-Debug image:
-
-```bash
-cd tools
-./build_debug.sh
-```
-
-Release image:
-
-```bash
-cd tools
-./build_release.sh
-```
-
-Both scripts produce a `kernel8.img` under `target/aarch64-unknown-none/<profile>/`.
-
-## Run In QEMU
-
-1. Generate an SD image with firmware files:
-
-```bash
-cd tools
-./generate_sd_card.sh
-```
-
-2. Start the emulator:
-
-```bash
-cd tools
-./start_simulator.sh
-```
-
-For debug mode with the GDB stub enabled (`-S -s`):
-
-```bash
-cd tools
-./start_simulator_debug.sh
-```
-
-## Deploy To Hardware
-
-Use the TFTP workflow to deploy to a Raspberry Pi:
-
-1. Copy `.env.example` to `.env` and fill in your values:
-   - `REMOTE_USER`
-   - `REMOTE_HOST`
-   - `TFTP_PATH`
-   - `BUILD_PATH`
-   - `BINARY_NAME`
-   - `KERNEL_NAME`
-2. Run:
-
-```bash
-cd tools
-./deply_to_hw.sh
-```
-
-## Notes
-
-- This is an educational kernel project and is actively evolving.
-- Interfaces and boot flow may change as features are added.

link.ld

@@ -4,13 +4,9 @@ SECTIONS {
     .text ALIGN(4) : {
         KEEP(*(.text._start))
         *(.text .text.*)
-    }
-    .vector_table ALIGN(2K) : {
-        KEEP(*(.vector_t))
-    }
-
         . = ALIGN(4K);
         __text_end = .;
+    }
 
     .rodata : {
         *(.rodata .rodata.*)
@@ -30,6 +26,10 @@ SECTIONS {
 
     __share_end = .;
 
+    .vector_table ALIGN(2K) : {
+        KEEP(*(.vector_table))
+    }
+
     # EL2 Stack
     .stack ALIGN(16): {
     __stack_start = .;

src/aarch64/mmu.rs

@@ -43,61 +43,14 @@ const L2_BLOCK_BITMAP_WORDS: usize = LEVEL2_BLOCK_SIZE / (64 * GRANULARITY);
 const MAX_PAGE_COUNT: usize = 1024 * 1024 * 1024 / GRANULARITY;
 
 const TRANSLATION_TABLE_BASE_ADDR: usize = 0xFFFF_FF82_0000_0000;
-#[no_mangle]
+pub const KERNEL_VIRTUAL_MEM_SPACE: usize = 0xFFFF_FF80_0000_0000;
-pub static KERNEL_VIRTUAL_MEM_SPACE: usize = 0xFFFF_FF80_0000_0000;
 
 pub const STACK_START_ADDR: usize = !KERNEL_VIRTUAL_MEM_SPACE & (!0xF);
 
-pub mod physical_mapping;
+mod physical_mapping;
 
-pub type VirtAddr = usize;
+type VirtAddr = usize;
-pub type PhysAddr = usize;
+type PhysAddr = usize;
-
-#[derive(Clone, Copy)]
-pub struct TableEntry {
-    value: u64,
-}
-
-impl TableEntry {
-    pub fn invalid() -> Self {
-        Self { value: 0 }
-    }
-
-    fn table_descriptor(addr: PhysAddr) -> Self {
-        Self {
-            value: (addr as u64 & 0x0000_FFFF_FFFF_F000) | TABLE,
-        }
-    }
-
-    fn block_descriptor(physical_address: usize, additional_flags: u64) -> Self {
-        Self {
-            value: (physical_address as u64 & 0x0000_FFFF_FFFF_F000)
-                | BLOCK
-                | ACCESS_FLAG
-                | INNER_SHAREABILITY
-                | additional_flags,
-        }
-    }
-
-    fn page_descriptor(physical_address: usize, additional_flags: u64) -> Self {
-        Self {
-            value: (physical_address as u64 & 0x0000_FFFF_FFFF_F000)
-                | PAGE
-                | ACCESS_FLAG
-                | INNER_SHAREABILITY
-                | additional_flags,
-        }
-    }
-
-    fn is_invalid(self) -> bool {
-        self.value & 0b11 == 0
-    }
-
-    #[inline]
-    fn address(self) -> PhysAddr {
-        self.value as usize & 0x0000_FFFF_FFFF_F000
-    }
-}
 
 pub enum PhysSource {
     Any,
@@ -105,24 +58,12 @@ pub enum PhysSource {
 }
 
 #[repr(align(4096))]
-pub struct PageTable(pub [TableEntry; TABLE_ENTRY_COUNT]);
+pub struct PageTable([u64; TABLE_ENTRY_COUNT]);
 
-impl Iterator for PageTable {
-    type Item = VirtAddr;
-
-    fn next(&mut self) -> Option<Self::Item> {
-        for (offset, entity) in self.0.iter().enumerate() {
-            if entity.is_invalid() {
-                return Some(offset);
-            }
-        }
-        None
-    }
-}
 #[no_mangle]
-pub static mut TRANSLATIONTABLE_TTBR0: PageTable = PageTable([TableEntry { value: 0 }; 512]);
+pub static mut TRANSLATIONTABLE_TTBR0: PageTable = PageTable([0; 512]);
 #[no_mangle]
-pub static mut TRANSLATIONTABLE_TTBR1: PageTable = PageTable([TableEntry { value: 0 }; 512]);
+pub static mut TRANSLATIONTABLE_TTBR1: PageTable = PageTable([0; 512]);
 
 /// Allocate a memory block of `size` starting at `virtual_address`.
 pub fn allocate_memory(
@@ -161,7 +102,7 @@ fn map_range_explicit(
 ) -> Result<(), NovaError> {
     let mut remaining = size_bytes;
 
-    while !virt.is_multiple_of(LEVEL2_BLOCK_SIZE) && remaining > 0 {
+    while virt % LEVEL2_BLOCK_SIZE != 0 {
         map_page(virt, phys, base, flags)?;
         (virt, _) = virt.overflowing_add(GRANULARITY);
         phys += GRANULARITY;
@@ -204,12 +145,13 @@ fn map_range_dynamic(
         (virt, _) = virt.overflowing_add(GRANULARITY);
         remaining -= GRANULARITY;
     }
+
     Ok(())
 }
 
 /// Allocate a singe page.
 pub fn alloc_page(
-    virtual_address: VirtAddr,
+    virtual_address: usize,
     base_table: *mut PageTable,
     additional_flags: u64,
 ) -> Result<(), NovaError> {
@@ -221,28 +163,6 @@ pub fn alloc_page(
     )
 }
 
-/// Allocate a singe page in one block.
-pub fn find_free_kerne_page_in_block(start: VirtAddr) -> Result<VirtAddr, NovaError> {
-    if !start.is_multiple_of(LEVEL2_BLOCK_SIZE) {
-        return Err(NovaError::Misalignment);
-    }
-
-    let (off1, off2, _) = virtual_address_to_table_offset(start);
-    let offsets = [off1, off2];
-    let table = unsafe {
-        &mut *navigate_table(
-            core::ptr::addr_of_mut!(TRANSLATIONTABLE_TTBR1),
-            &offsets,
-            true,
-        )?
-    };
-
-    if let Some(offset) = table.next() {
-        return Ok(start + (offset * GRANULARITY));
-    }
-    Err(NovaError::OutOfMeomory)
-}
-
 /// Allocate a single page at an explicit `physical_address`.
 pub fn alloc_page_explicit(
     virtual_address: usize,
@@ -269,14 +189,14 @@ pub fn map_page(
 
     let offsets = [l1_off, l2_off];
 
-    let table_ptr = navigate_table(base_table_ptr, &offsets, true)?;
+    let table_ptr = navigate_table(base_table_ptr, &offsets)?;
     let table = unsafe { &mut *table_ptr };
 
-    if !table.0[l3_off].is_invalid() {
+    if table.0[l3_off] & 0b11 > 0 {
-        return Err(NovaError::Paging("Page already occupied."));
+        return Err(NovaError::Paging);
     }
 
-    table.0[l3_off] = TableEntry::page_descriptor(physical_address, additional_flags);
+    table.0[l3_off] = create_page_descriptor_entry(physical_address, additional_flags);
 
     Ok(())
 }
@@ -309,16 +229,16 @@ pub fn map_l2_block(
 ) -> Result<(), NovaError> {
     let (l1_off, l2_off, _) = virtual_address_to_table_offset(virtual_addr);
     let offsets = [l1_off];
-    let table_ptr = navigate_table(base_table_ptr, &offsets, true)?;
+    let table_ptr = navigate_table(base_table_ptr, &offsets)?;
 
     let table = unsafe { &mut *table_ptr };
 
     // Verify virtual address is available.
-    if !table.0[l2_off].is_invalid() {
+    if table.0[l2_off] & 0b11 != 0 {
-        return Err(NovaError::Paging("Block already occupied."));
+        return Err(NovaError::Paging);
     }
 
-    let new_entry = TableEntry::block_descriptor(physical_address, additional_flags);
+    let new_entry = create_block_descriptor_entry(physical_address, additional_flags);
 
     table.0[l2_off] = new_entry;
 
@@ -358,6 +278,26 @@ pub fn reserve_range(
     Ok(start_physical_address)
 }
 
+fn create_block_descriptor_entry(physical_address: usize, additional_flags: u64) -> u64 {
+    (physical_address as u64 & 0x0000_FFFF_FFFF_F000)
+        | BLOCK
+        | ACCESS_FLAG
+        | INNER_SHAREABILITY
+        | additional_flags
+}
+
+fn create_page_descriptor_entry(physical_address: usize, additional_flags: u64) -> u64 {
+    (physical_address as u64 & 0x0000_FFFF_FFFF_F000)
+        | PAGE
+        | ACCESS_FLAG
+        | INNER_SHAREABILITY
+        | additional_flags
+}
+
+fn create_table_descriptor_entry(addr: usize) -> u64 {
+    (addr as u64 & 0x0000_FFFF_FFFF_F000) | TABLE
+}
+
 fn virtual_address_to_table_offset(virtual_addr: usize) -> (usize, usize, usize) {
     let absolute_page_off = (virtual_addr & !KERNEL_VIRTUAL_MEM_SPACE) / GRANULARITY;
     let l3_off = absolute_page_off % TABLE_ENTRY_COUNT;
@@ -371,11 +311,10 @@ fn virtual_address_to_table_offset(virtual_addr: usize) -> (usize, usize, usize)
 fn navigate_table(
     initial_table_ptr: *mut PageTable,
     offsets: &[usize],
-    create_missing: bool,
 ) -> Result<*mut PageTable, NovaError> {
     let mut table = initial_table_ptr;
     for offset in offsets {
-        table = next_table(table, *offset, create_missing)?;
+        table = next_table(table, *offset)?;
     }
     Ok(table)
 }
@@ -383,20 +322,13 @@ fn navigate_table(
 /// Get the next table one level down.
 ///
 /// If table doesn't exit a page will be allocated for it.
-fn next_table(
+fn next_table(table_ptr: *mut PageTable, offset: usize) -> Result<*mut PageTable, NovaError> {
-    table_ptr: *mut PageTable,
-    offset: usize,
-    create_missing: bool,
-) -> Result<*mut PageTable, NovaError> {
     let table = unsafe { &mut *table_ptr };
-    match table.0[offset].value & 0b11 {
+    match table.0[offset] & 0b11 {
         0 => {
-            if !create_missing {
-                return Err(NovaError::Paging("No table defined."));
-            }
             let new_phys_page_table_address = reserve_page();
 
-            table.0[offset] = TableEntry::table_descriptor(new_phys_page_table_address);
+            table.0[offset] = create_table_descriptor_entry(new_phys_page_table_address);
             map_page(
                 phys_table_to_kernel_space(new_phys_page_table_address),
                 new_phys_page_table_address,
@@ -404,31 +336,26 @@ fn next_table(
                 NORMAL_MEM | WRITABLE | PXN | UXN,
             )?;
 
-            Ok(resolve_table_addr(table.0[offset].address()) as *mut PageTable)
+            Ok(entry_table_addr(table.0[offset] as usize) as *mut PageTable)
         }
-        1 => Err(NovaError::Paging(
+        1 => Err(NovaError::Paging),
-            "Can't navigate table due to block mapping.",
+        3 => Ok(entry_table_addr(table.0[offset] as usize) as *mut PageTable),
-        )),
-        3 => Ok(resolve_table_addr(table.0[offset].address()) as *mut PageTable),
         _ => unreachable!(),
     }
 }
 
-/// Converts a physical table address and returns the corresponding virtual address depending on EL.
+/// Extracts the physical address out of an table entry.
-///
-/// - `== EL0` -> panic
-/// - `== EL1` -> 0xFFFFFF82XXXXXXXX
-/// - `>= EL2` -> physical address
 #[inline]
-fn resolve_table_addr(physical_address: PhysAddr) -> VirtAddr {
+fn entry_phys(entry: usize) -> PhysAddr {
-    let current_el = get_current_el();
+    entry & 0x0000_FFFF_FFFF_F000
+}
 
-    if current_el >= 2 {
+#[inline]
-        physical_address
+fn entry_table_addr(entry: usize) -> VirtAddr {
-    } else if get_current_el() == 1 {
+    if get_current_el() == 1 {
-        phys_table_to_kernel_space(physical_address)
+        phys_table_to_kernel_space(entry_phys(entry))
     } else {
-        panic!("Access to table entries is forbidden in EL0.")
+        entry_phys(entry)
     }
 }
 

src/aarch64/mmu/physical_mapping.rs

@@ -1,19 +1,13 @@
 use crate::aarch64::mmu::{PhysAddr, GRANULARITY, L2_BLOCK_BITMAP_WORDS, MAX_PAGE_COUNT};
 use nova_error::NovaError;
 
-struct PagingMap {
+static mut PAGING_BITMAP: [u64; MAX_PAGE_COUNT / 64] = [0; MAX_PAGE_COUNT / 64];
-    bitmap: [u64; MAX_PAGE_COUNT / 64],
-}
-
-static mut PAGING_BITMAP: PagingMap = PagingMap {
-    bitmap: [0; MAX_PAGE_COUNT / 64],
-};
 
 pub fn reserve_page() -> PhysAddr {
     if let Some(address) = find_unallocated_page() {
         let page = address / GRANULARITY;
         let word_index = page / 64;
-        unsafe { PAGING_BITMAP.bitmap[word_index] |= 1 << (page % 64) };
+        unsafe { PAGING_BITMAP[word_index] |= 1 << (page % 64) };
         return address;
     }
     panic!("Out of Memory!");
@@ -23,18 +17,18 @@ pub fn reserve_page_explicit(physical_address: usize) -> Result<PhysAddr, NovaEr
     let page = physical_address / GRANULARITY;
     let word_index = page / 64;
 
-    if unsafe { PAGING_BITMAP.bitmap[word_index] } & (1 << (page % 64)) > 0 {
+    if unsafe { PAGING_BITMAP[word_index] } & (1 << (page % 64)) > 0 {
-        return Err(NovaError::Paging("Page PA already taken."));
+        return Err(NovaError::Paging);
     }
 
-    unsafe { PAGING_BITMAP.bitmap[word_index] |= 1 << (page % 64) };
+    unsafe { PAGING_BITMAP[word_index] |= 1 << (page % 64) };
     Ok(physical_address)
 }
 
 pub fn reserve_block() -> usize {
     if let Some(start) = find_contiguous_free_bitmap_words(L2_BLOCK_BITMAP_WORDS) {
         for j in 0..L2_BLOCK_BITMAP_WORDS {
-            unsafe { PAGING_BITMAP.bitmap[start + j] = u64::MAX };
+            unsafe { PAGING_BITMAP[start + j] = u64::MAX };
         }
         return start * 64 * GRANULARITY;
     }
@@ -46,21 +40,21 @@ pub fn reserve_block_explicit(physical_address: usize) -> Result<(), NovaError>
     let page = physical_address / GRANULARITY;
     for i in 0..L2_BLOCK_BITMAP_WORDS {
         unsafe {
-            if PAGING_BITMAP.bitmap[(page / 64) + i] != 0 {
+            if PAGING_BITMAP[(page / 64) + i] != 0 {
-                return Err(NovaError::Paging("Block PA already taken."));
+                return Err(NovaError::Paging);
             }
         };
     }
     for i in 0..L2_BLOCK_BITMAP_WORDS {
         unsafe {
-            PAGING_BITMAP.bitmap[(page / 64) + i] = u64::MAX;
+            PAGING_BITMAP[(page / 64) + i] = u64::MAX;
         };
     }
     Ok(())
 }
 
 fn find_unallocated_page() -> Option<usize> {
-    for (i, entry) in unsafe { PAGING_BITMAP.bitmap }.iter().enumerate() {
+    for (i, entry) in unsafe { PAGING_BITMAP }.iter().enumerate() {
         if *entry != u64::MAX {
             for offset in 0..64 {
                 if entry >> offset & 0b1 == 0 {
@@ -76,7 +70,7 @@ fn find_contiguous_free_bitmap_words(required_words: usize) -> Option<usize> {
     let mut run_start = 0;
     let mut run_len = 0;
 
-    for (i, entry) in unsafe { PAGING_BITMAP.bitmap }.iter().enumerate() {
+    for (i, entry) in unsafe { PAGING_BITMAP }.iter().enumerate() {
         if *entry == 0 {
             if run_len == 0 {
                 run_start = i;

src/application_manager.rs

@@ -1,145 +0,0 @@
-use crate::{
-    aarch64::mmu::{
-        find_free_kerne_page_in_block, map_page, physical_mapping::reserve_page, PageTable,
-        TableEntry, VirtAddr, NORMAL_MEM, TRANSLATIONTABLE_TTBR0, TRANSLATIONTABLE_TTBR1, WRITABLE,
-    },
-    configuration::memory_mapping::{APPLICATION_TRANSLATION_TABLE_VA, EL0_STACK_TOP},
-};
-use alloc::vec::Vec;
-use core::{arch::asm, mem, ptr::write_volatile};
-use log::error;
-use nova_error::NovaError;
-use spin::Mutex;
-
-struct AppManager {
-    apps: Option<Vec<Application>>,
-}
-
-impl AppManager {
-    const fn new() -> Self {
-        Self { apps: None }
-    }
-}
-
-unsafe impl Send for AppManager {}
-
-pub struct Application {
-    pub table_ptr: *mut TableEntry,
-    pub start_addr: usize,
-    pub stack_pointer: usize,
-}
-
-impl Application {
-    pub fn new(start_addr: VirtAddr) -> Self {
-        let physical_addr = reserve_page();
-        let virtual_address =
-            find_free_kerne_page_in_block(APPLICATION_TRANSLATION_TABLE_VA).unwrap();
-
-        map_page(
-            virtual_address,
-            physical_addr,
-            core::ptr::addr_of_mut!(TRANSLATIONTABLE_TTBR1),
-            NORMAL_MEM | WRITABLE,
-        )
-        .unwrap();
-
-        // TODO: Temporary solution, while kernel and app share some memory regions
-        #[allow(static_mut_refs)]
-        unsafe {
-            let table = &mut *(virtual_address as *mut PageTable);
-            table.0 = TRANSLATIONTABLE_TTBR0.0;
-        }
-
-        Self {
-            table_ptr: physical_addr as *mut TableEntry,
-            start_addr,
-            stack_pointer: EL0_STACK_TOP,
-        }
-    }
-
-    pub unsafe fn configure_registers(&self) {
-        asm!("msr ELR_EL1, {}", in(reg) self.start_addr);
-        asm!("msr SPSR_EL1, {0:x}", in(reg) 0);
-        asm!("msr SP_EL0, {0:x}", in(reg) self.stack_pointer);
-        asm!("msr TTBR0_EL1, {}", in(reg) self.table_ptr as usize);
-    }
-
-    /// Starts an application.
-    ///
-    /// `ELR_EL1` ->  Exception Link Register (starting virtual address)
-    /// `SPSR_EL1` -> Saved Program State Register (settings for `eret` behaviour)
-    /// `SP_EL0` -> Stack Pointer Register (virtual_address of stack Pointer)
-    /// `TTBR0_EL1` -> Translation Table base Register Register
-    pub fn start(&mut self, args: Vec<&str>) {
-        let size = args.len();
-        let argv = self.construct_inital_stack(args);
-        unsafe {
-            self.configure_registers();
-            asm!("", in("x0") size, in("x1") argv);
-            asm!("eret");
-        }
-    }
-
-    /// Initializes the stack based on the System V ABI
-    fn construct_inital_stack(&mut self, args: Vec<&str>) -> usize {
-        let size = args.len();
-        let mut arg_addresses = Vec::with_capacity(size);
-
-        // Write strings into stack
-        for value in args {
-            self.stack_pointer -= value.len() * mem::size_of::<u8>();
-            let pointer = self.stack_pointer as *mut u8;
-            unsafe { core::ptr::copy(value.as_ptr(), pointer, value.len()) };
-            arg_addresses.push(pointer);
-        }
-        self.stack_pointer = align_down(self.stack_pointer, 16);
-
-        // TODO: Auxiliry vector entry
-        // TODO: Environment pointers
-
-        let argv = self.stack_pointer;
-
-        // Write argument pointers into stack
-        for addr in arg_addresses {
-            unsafe { write_volatile(self.stack_pointer as *mut *const u8, addr) };
-            self.stack_pointer -= mem::size_of::<*const u8>();
-        }
-
-        argv
-    }
-}
-
-fn align_down(sp: usize, align: usize) -> usize {
-    sp & !(align - 1)
-}
-
-static APP_MANAGER: Mutex<AppManager> = Mutex::new(AppManager::new());
-
-pub fn initialize_app_manager() {
-    let mut guard = APP_MANAGER.lock();
-    guard.apps = Some(Vec::new());
-}
-
-pub fn add_app(app: Application) -> Result<(), NovaError> {
-    if let Some(app_list) = APP_MANAGER.lock().apps.as_mut() {
-        app_list.push(app);
-        Ok(())
-    } else {
-        Err(NovaError::General("AppManager not initalized."))
-    }
-}
-
-pub fn start_app(index: usize, args: Vec<&str>) -> Result<(), NovaError> {
-    if let Some(app) = APP_MANAGER
-        .lock()
-        .apps
-        .as_mut()
-        .and_then(|am| am.get_mut(index))
-    {
-        app.start(args);
-        unreachable!()
-    } else {
-        error!("Unable to start app due to invalid App ID.");
-        Err(NovaError::General("Invalid app id."))
-    }
-}

src/config.S

@@ -10,12 +10,8 @@ el2_to_el1:
     msr SPSR_EL2, x0
 
     // Set return address to kernel_main
-    adrp x0, KERNEL_VIRTUAL_MEM_SPACE
-    ldr x1, [x0, :lo12:KERNEL_VIRTUAL_MEM_SPACE]
-
     adrp x0, kernel_main
     add  x0, x0, :lo12:kernel_main
-    orr  x0, x0, x1
     msr ELR_EL2, x0
 
     // Set SP_EL1 to stack base
@@ -78,3 +74,121 @@ configure_mmu_el1:
 
     ret
 
+.align 4
+.global el1_to_el0
+el1_to_el0:
+
+    // Set SPSR_EL1: return to EL0t
+    mov x0, #(0b0000)
+    msr SPSR_EL1, x0
+
+    // Set return address to el0
+    ldr x0, =el0
+    msr ELR_EL1, x0
+
+    // Set SP_EL1 to stack base
+    adrp x0, EL0_STACK_TOP
+    ldr  x1, [x0, :lo12:EL0_STACK_TOP]
+    msr SP_EL0, x1
+
+    isb
+
+    // Return to EL0
+    eret
+
+
+.align 4
+irq_handler:
+    sub sp, sp, #176
+    stp x0, x1, [sp, #0]
+    stp x2, x3, [sp, #16]
+    stp x4, x5, [sp, #32]
+    stp x6, x7, [sp, #48]
+    stp x8, x9, [sp, #64]
+    stp x10, x11, [sp, #80]
+    stp x12, x13, [sp, #96]
+    stp x14, x15, [sp, #112]
+    stp x16, x17, [sp, #128]
+    stp x18, x29, [sp, #144]
+    stp x30, xzr, [sp, #160]
+
+    bl rust_irq_handler
+
+    ldp x0, x1, [sp, #0]
+    ldp x2, x3, [sp, #16]
+    ldp x4, x5, [sp, #32]
+    ldp x6, x7, [sp, #48]
+    ldp x8, x9, [sp, #64]
+    ldp x10, x11, [sp, #80]
+    ldp x12, x13, [sp, #96]
+    ldp x14, x15, [sp, #112]
+    ldp x16, x17, [sp, #128]
+    ldp x18, x29, [sp, #144]
+    ldp x30, xzr, [sp, #160]
+    add sp, sp, #176
+
+    eret
+
+.align 4
+synchronous_interrupt_imm_lower_aarch64:
+    sub sp, sp, #176
+    stp x0, x1, [sp, #0]
+    stp x2, x3, [sp, #16]
+    stp x4, x5, [sp, #32]
+    stp x6, x7, [sp, #48]
+    stp x8, x9, [sp, #64]
+    stp x10, x11, [sp, #80]
+    stp x12, x13, [sp, #96]
+    stp x14, x15, [sp, #112]
+    stp x16, x17, [sp, #128]
+    stp x18, x29, [sp, #144]
+    stp x30, xzr, [sp, #160]
+
+    bl rust_synchronous_interrupt_imm_lower_aarch64
+
+    ldp x0, x1, [sp, #0]
+    ldp x2, x3, [sp, #16]
+    ldp x4, x5, [sp, #32]
+    ldp x6, x7, [sp, #48]
+    ldp x8, x9, [sp, #64]
+    ldp x10, x11, [sp, #80]
+    ldp x12, x13, [sp, #96]
+    ldp x14, x15, [sp, #112]
+    ldp x16, x17, [sp, #128]
+    ldp x18, x29, [sp, #144]
+    ldp x30, xzr, [sp, #160]
+    add sp, sp, #176
+
+    eret
+
+.align 4
+synchronous_interrupt_no_el_change:
+    sub sp, sp, #176
+    stp x0, x1, [sp, #0]
+    stp x2, x3, [sp, #16]
+    stp x4, x5, [sp, #32]
+    stp x6, x7, [sp, #48]
+    stp x8, x9, [sp, #64]
+    stp x10, x11, [sp, #80]
+    stp x12, x13, [sp, #96]
+    stp x14, x15, [sp, #112]
+    stp x16, x17, [sp, #128]
+    stp x18, x29, [sp, #144]
+    stp x30, xzr, [sp, #160]
+
+    bl rust_synchronous_interrupt_no_el_change
+
+    ldp x0, x1, [sp, #0]
+    ldp x2, x3, [sp, #16]
+    ldp x4, x5, [sp, #32]
+    ldp x6, x7, [sp, #48]
+    ldp x8, x9, [sp, #64]
+    ldp x10, x11, [sp, #80]
+    ldp x12, x13, [sp, #96]
+    ldp x14, x15, [sp, #112]
+    ldp x16, x17, [sp, #128]
+    ldp x18, x29, [sp, #144]
+    ldp x30, xzr, [sp, #160]
+    add sp, sp, #176
+
+    eret

src/configuration.rs

@@ -31,4 +31,99 @@ const AS: u64 = 0b1 << 36; // configure an ASID size of 16 bits
 #[no_mangle]
 pub static TCR_EL1_CONF: u64 = IPS | TG0 | TG1 | T0SZ | T1SZ | SH0 | SH1 | AS;
 
-pub mod memory_mapping;
+pub mod mmu {
+    use crate::{
+        aarch64::mmu::{
+            alloc_block_l2_explicit, allocate_memory, map_l2_block, map_page, reserve_range,
+            PhysSource, DEVICE_MEM, EL0_ACCESSIBLE, GRANULARITY, KERNEL_VIRTUAL_MEM_SPACE,
+            LEVEL1_BLOCK_SIZE, LEVEL2_BLOCK_SIZE, NORMAL_MEM, PXN, READ_ONLY, STACK_START_ADDR,
+            TRANSLATIONTABLE_TTBR0, UXN, WRITABLE,
+        },
+        PERIPHERAL_BASE,
+    };
+
+    #[no_mangle]
+    static EL1_STACK_TOP: usize = STACK_START_ADDR | KERNEL_VIRTUAL_MEM_SPACE;
+    const EL1_STACK_SIZE: usize = LEVEL2_BLOCK_SIZE * 2;
+    #[no_mangle]
+    static EL0_STACK_TOP: usize = STACK_START_ADDR;
+    const EL0_STACK_SIZE: usize = LEVEL2_BLOCK_SIZE * 2;
+    extern "C" {
+        static __text_end: u64;
+        static __share_end: u64;
+        static __kernel_end: u64;
+    }
+
+    pub fn initialize_mmu_translation_tables() {
+        let text_end = unsafe { &__text_end } as *const _ as usize;
+        let shared_segment_end = unsafe { &__share_end } as *const _ as usize;
+        let kernel_end = unsafe { &__kernel_end } as *const _ as usize;
+
+        reserve_range(0x0, kernel_end).unwrap();
+
+        for addr in (0..text_end).step_by(GRANULARITY) {
+            map_page(
+                addr,
+                addr,
+                core::ptr::addr_of_mut!(TRANSLATIONTABLE_TTBR0),
+                EL0_ACCESSIBLE | READ_ONLY | NORMAL_MEM,
+            )
+            .unwrap();
+        }
+
+        for addr in (text_end..shared_segment_end).step_by(GRANULARITY) {
+            map_page(
+                addr,
+                addr,
+                core::ptr::addr_of_mut!(TRANSLATIONTABLE_TTBR0),
+                EL0_ACCESSIBLE | WRITABLE | NORMAL_MEM,
+            )
+            .unwrap();
+        }
+
+        for addr in (shared_segment_end..kernel_end).step_by(LEVEL2_BLOCK_SIZE) {
+            map_l2_block(
+                addr,
+                addr,
+                core::ptr::addr_of_mut!(TRANSLATIONTABLE_TTBR0),
+                WRITABLE | UXN | NORMAL_MEM,
+            )
+            .unwrap();
+        }
+
+        for addr in (PERIPHERAL_BASE..LEVEL1_BLOCK_SIZE).step_by(LEVEL2_BLOCK_SIZE) {
+            alloc_block_l2_explicit(
+                addr,
+                addr,
+                core::ptr::addr_of_mut!(TRANSLATIONTABLE_TTBR0),
+                EL0_ACCESSIBLE | WRITABLE | UXN | PXN | DEVICE_MEM,
+            )
+            .unwrap();
+        }
+
+        // Frame Buffer memory range
+        allocate_memory(
+            0x3c100000,
+            1080 * 1920 * 4,
+            PhysSource::Explicit(0x3c100000),
+            NORMAL_MEM | PXN | UXN | WRITABLE | EL0_ACCESSIBLE,
+        )
+        .unwrap();
+
+        allocate_memory(
+            EL1_STACK_TOP - EL1_STACK_SIZE + 0x10,
+            EL1_STACK_SIZE,
+            PhysSource::Any,
+            WRITABLE | NORMAL_MEM,
+        )
+        .unwrap();
+
+        allocate_memory(
+            EL0_STACK_TOP - EL0_STACK_SIZE + 0x10,
+            EL0_STACK_SIZE,
+            PhysSource::Any,
+            WRITABLE | EL0_ACCESSIBLE | NORMAL_MEM,
+        )
+        .unwrap();
+    }
+}

src/configuration/memory_mapping.rs

@@ -1,127 +0,0 @@
-use crate::{
-    aarch64::mmu::{
-        alloc_block_l2_explicit, allocate_memory, map_page, physical_mapping::reserve_page,
-        reserve_range, PhysAddr, PhysSource, VirtAddr, DEVICE_MEM, EL0_ACCESSIBLE, GRANULARITY,
-        KERNEL_VIRTUAL_MEM_SPACE, LEVEL1_BLOCK_SIZE, LEVEL2_BLOCK_SIZE, NORMAL_MEM, PXN, READ_ONLY,
-        STACK_START_ADDR, TRANSLATIONTABLE_TTBR0, TRANSLATIONTABLE_TTBR1, UXN, WRITABLE,
-    },
-    PERIPHERAL_BASE,
-};
-
-#[no_mangle]
-static EL1_STACK_TOP: usize = STACK_START_ADDR | KERNEL_VIRTUAL_MEM_SPACE;
-const EL1_STACK_SIZE: usize = LEVEL2_BLOCK_SIZE * 2;
-#[no_mangle]
-pub static EL0_STACK_TOP: usize = STACK_START_ADDR;
-pub const EL0_STACK_SIZE: usize = LEVEL2_BLOCK_SIZE * 2;
-
-pub const MAILBOX_VIRTUAL_ADDRESS: VirtAddr = 0xFFFF_FF81_FFFF_E000;
-pub static mut MAILBOX_PHYSICAL_ADDRESS: Option<PhysAddr> = None;
-
-// TODO: Currently limited to 512 applications, more than enough, but has to be kept
-// in mind
-pub const APPLICATION_TRANSLATION_TABLE_VA: VirtAddr = 0xFFFF_FF81_FE00_0000;
-
-extern "C" {
-    static __text_end: u64;
-    static __share_end: u64;
-    static __kernel_end: u64;
-}
-
-pub fn initialize_mmu_translation_tables() {
-    let text_end = unsafe { &__text_end } as *const _ as usize;
-    let shared_segment_end = unsafe { &__share_end } as *const _ as usize;
-    let kernel_end = unsafe { &__kernel_end } as *const _ as usize;
-
-    reserve_range(0x0, kernel_end).unwrap();
-
-    for addr in (0..text_end).step_by(GRANULARITY) {
-        map_page(
-            addr,
-            addr,
-            core::ptr::addr_of_mut!(TRANSLATIONTABLE_TTBR0),
-            EL0_ACCESSIBLE | READ_ONLY | NORMAL_MEM,
-        )
-        .unwrap();
-    }
-
-    for addr in (0..text_end).step_by(GRANULARITY) {
-        map_page(
-            addr | KERNEL_VIRTUAL_MEM_SPACE,
-            addr,
-            core::ptr::addr_of_mut!(TRANSLATIONTABLE_TTBR1),
-            READ_ONLY | NORMAL_MEM,
-        )
-        .unwrap();
-    }
-
-    for addr in (text_end..shared_segment_end).step_by(GRANULARITY) {
-        map_page(
-            addr,
-            addr,
-            core::ptr::addr_of_mut!(TRANSLATIONTABLE_TTBR0),
-            EL0_ACCESSIBLE | WRITABLE | NORMAL_MEM,
-        )
-        .unwrap();
-    }
-
-    for addr in (text_end..shared_segment_end).step_by(GRANULARITY) {
-        map_page(
-            addr | KERNEL_VIRTUAL_MEM_SPACE,
-            addr,
-            core::ptr::addr_of_mut!(TRANSLATIONTABLE_TTBR1),
-            EL0_ACCESSIBLE | WRITABLE | NORMAL_MEM,
-        )
-        .unwrap();
-    }
-
-    for addr in (PERIPHERAL_BASE..LEVEL1_BLOCK_SIZE).step_by(LEVEL2_BLOCK_SIZE) {
-        alloc_block_l2_explicit(
-            addr,
-            addr,
-            core::ptr::addr_of_mut!(TRANSLATIONTABLE_TTBR0),
-            EL0_ACCESSIBLE | WRITABLE | UXN | PXN | DEVICE_MEM,
-        )
-        .unwrap();
-    }
-
-    // Frame Buffer memory range
-    allocate_memory(
-        0x3c100000,
-        1080 * 1920 * 4,
-        PhysSource::Explicit(0x3c100000),
-        NORMAL_MEM | PXN | UXN | WRITABLE | EL0_ACCESSIBLE,
-    )
-    .unwrap();
-
-    // Allocate EL1 stack
-    allocate_memory(
-        EL1_STACK_TOP - EL1_STACK_SIZE + 0x10,
-        EL1_STACK_SIZE,
-        PhysSource::Any,
-        WRITABLE | NORMAL_MEM,
-    )
-    .unwrap();
-
-    // Allocate EL0 stack
-    allocate_memory(
-        EL0_STACK_TOP - EL0_STACK_SIZE + 0x10,
-        EL0_STACK_SIZE,
-        PhysSource::Any,
-        WRITABLE | EL0_ACCESSIBLE | NORMAL_MEM,
-    )
-    .unwrap();
-
-    // Allocate Mailbox buffer
-    {
-        let addr = reserve_page();
-        unsafe { MAILBOX_PHYSICAL_ADDRESS = Some(addr) };
-        allocate_memory(
-            MAILBOX_VIRTUAL_ADDRESS,
-            GRANULARITY,
-            PhysSource::Explicit(addr),
-            WRITABLE | NORMAL_MEM,
-        )
-        .unwrap();
-    }
-}

src/console.rs

@@ -1,92 +0,0 @@
-use alloc::string::String;
-
-use crate::{
-    application_manager::start_app,
-    interrupt_handlers::irq::{register_interrupt_handler, IRQSource},
-    peripherals::uart::read_uart_data,
-    pi3::mailbox::read_soc_temp,
-    print, println,
-};
-
-pub static mut TERMINAL: Option<Terminal> = None;
-
-pub struct Terminal {
-    input: String,
-}
-
-impl Default for Terminal {
-    fn default() -> Self {
-        Self::new()
-    }
-}
-
-impl Terminal {
-    pub fn new() -> Self {
-        Self {
-            input: String::new(),
-        }
-    }
-
-    fn flush(&mut self) {
-        print!("\n> {}", self.input);
-    }
-
-    fn exec(&mut self) {
-        print!("\n");
-        let val = self.input.clone();
-        self.input.clear();
-
-        let mut parts = val.split(" ");
-
-        match parts.next().unwrap() {
-            "temp" => {
-                println!("{}", read_soc_temp([0]).unwrap()[1]);
-            }
-            "app" => {
-                if let Some(app_id) = parts.next().and_then(|a| a.parse::<usize>().ok()) {
-                    let args = parts.collect();
-                    let _ = start_app(app_id, args);
-                } else {
-                    println!("App ID not set.");
-                }
-            }
-            _ => {
-                println!("Unknown command: \"{}\"", self.input);
-            }
-        }
-        self.input.clear();
-    }
-}
-
-pub fn init_terminal() {
-    unsafe { TERMINAL = Some(Terminal::new()) };
-    register_terminal_interrupt_handler();
-}
-
-fn terminal_uart_rx_interrupt_handler() {
-    let input = read_uart_data();
-    #[allow(static_mut_refs)]
-    if let Some(term) = unsafe { TERMINAL.as_mut() } {
-        match input {
-            '\r' => {
-                term.exec();
-                term.flush();
-            }
-            _ => {
-                term.input.push(input);
-                print!("{}", input);
-            }
-        }
-    }
-}
-
-pub fn flush_terminal() {
-    #[allow(static_mut_refs)]
-    if let Some(term) = unsafe { TERMINAL.as_mut() } {
-        term.flush();
-    }
-}
-
-fn register_terminal_interrupt_handler() {
-    register_interrupt_handler(IRQSource::UartInt, terminal_uart_rx_interrupt_handler);
-}

src/framebuffer.rs

@@ -4,8 +4,10 @@ mod bitmaps;
 
 use bitmaps::BASIC_LEGACY;
 
-use crate::pi3::mailbox::{read_mailbox, write_mailbox};
+use crate::{
-use log::error;
+    pi3::mailbox::{read_mailbox, write_mailbox},
+    println,
+};
 #[repr(align(16))]
 struct Mailbox([u32; 36]);
 
@@ -235,7 +237,7 @@ impl Default for FrameBuffer {
 
         let _ = read_mailbox(8);
         if mailbox.0[1] == 0 {
-            error!("Mailbox request was not processed!");
+            println!("Failed");
         }
 
         mailbox.0[28] &= 0x3FFFFFFF;

src/interrupt_handlers.rs

@@ -1,10 +1,19 @@
 use core::arch::asm;
 
+use alloc::vec::Vec;
+
 use crate::{
-    aarch64::registers::{daif::mask_all, read_esr_el1, read_exception_source_el},
+    aarch64::registers::{
+        daif::{mask_all, unmask_irq},
+        read_elr_el1, read_esr_el1, read_exception_source_el,
+    },
     get_current_el,
+    peripherals::{
+        gpio::{read_gpio_event_detect_status, reset_gpio_event_detect_status},
+        uart::clear_uart_interrupt_state,
+    },
+    println, read_address, write_address,
 };
-use log::debug;
 
 const INTERRUPT_BASE: u32 = 0x3F00_B000;
 const IRQ_PENDING_BASE: u32 = INTERRUPT_BASE + 0x204;
@@ -13,29 +22,30 @@ const DISABLE_IRQ_BASE: u32 = INTERRUPT_BASE + 0x21C;
 
 const GPIO_PENDING_BIT_OFFSET: u64 = 0b1111 << 49;
 
-#[repr(C)]
+struct InterruptHandlers {
-pub struct TrapFrame {
+    source: IRQSource,
-    pub x0: u64,
+    function: fn(),
-    pub x1: u64,
+}
-    pub x2: u64,
+
-    pub x3: u64,
+// TODO: replace with hashmap and check for better alternatives for option
-    pub x4: u64,
+static mut INTERRUPT_HANDLERS: Option<Vec<InterruptHandlers>> = None;
-    pub x5: u64,
+
-    pub x6: u64,
+#[derive(Clone)]
-    pub x7: u64,
+#[repr(u32)]
-    pub x8: u64,
+pub enum IRQSource {
-    pub x9: u64,
+    AuxInt = 29,
-    pub x10: u64,
+    I2cSpiSlvInt = 44,
-    pub x11: u64,
+    Pwa0 = 45,
-    pub x12: u64,
+    Pwa1 = 46,
-    pub x13: u64,
+    Smi = 48,
-    pub x14: u64,
+    GpioInt0 = 49,
-    pub x15: u64,
+    GpioInt1 = 50,
-    pub x16: u64,
+    GpioInt2 = 51,
-    pub x17: u64,
+    GpioInt3 = 52,
-    pub x18: u64,
+    I2cInt = 53,
-    pub x29: u64,
+    SpiInt = 54,
-    pub x30: u64,
+    PcmInt = 55,
+    UartInt = 57,
 }
 
 /// Representation of the ESR_ELx registers
@@ -59,25 +69,160 @@ impl From<u32> for EsrElX {
     }
 }
 
-pub mod irq;
+#[no_mangle]
-pub mod synchronous;
+unsafe extern "C" fn rust_irq_handler() {
+    mask_all();
+    let pending_irqs = get_irq_pending_sources();
+
+    if pending_irqs & GPIO_PENDING_BIT_OFFSET != 0 {
+        handle_gpio_interrupt();
+        let source_el = read_exception_source_el() >> 2;
+        println!("Source EL: {}", source_el);
+        println!("Current EL: {}", get_current_el());
+        println!("Return register address: {:#x}", read_esr_el1());
+    }
+
+    if let Some(handler_vec) = unsafe { &*core::ptr::addr_of_mut!(INTERRUPT_HANDLERS) } {
+        for handler in handler_vec {
+            if (pending_irqs & (1 << (handler.source.clone() as u32))) != 0 {
+                (handler.function)();
+                clear_interrupt_for_source(handler.source.clone());
+            }
+        }
+    }
+}
 
 #[no_mangle]
 unsafe extern "C" fn rust_synchronous_interrupt_no_el_change() {
     mask_all();
 
     let source_el = read_exception_source_el() >> 2;
-    debug!("--------Sync Exception in EL{}--------", source_el);
+    println!("--------Sync Exception in EL{}--------", source_el);
-    debug!("No EL change");
+    println!("No EL change");
-    debug!("Current EL: {}", get_current_el());
+    println!("Current EL: {}", get_current_el());
-    debug!("{:?}", EsrElX::from(read_esr_el1()));
+    println!("{:?}", EsrElX::from(read_esr_el1()));
-    debug!("Return register address: {:#x}", read_esr_el1());
+    println!("Return register address: {:#x}", read_esr_el1());
-    debug!("-------------------------------------");
+    println!("-------------------------------------");
 }
 
-fn set_return_to_kernel_loop() {
+/// Synchronous Exception Handler
+///
+/// Lower Exception level, where the implemented level
+/// immediately lower than the target level is using
+/// AArch64.
+#[no_mangle]
+unsafe extern "C" fn rust_synchronous_interrupt_imm_lower_aarch64() {
+    mask_all();
+
+    let source_el = read_exception_source_el() >> 2;
+    println!("--------Sync Exception in EL{}--------", source_el);
+    println!("Exception escalated to EL {}", get_current_el());
+    println!("Current EL: {}", get_current_el());
+    let esr: EsrElX = EsrElX::from(read_esr_el1());
+    println!("{:?}", esr);
+    println!("Return address: {:#x}", read_elr_el1());
+
+    match esr.ec {
+        0b100100 => {
+            println!("Cause: Data Abort from a lower Exception level");
+        }
+        _ => {
+            println!("Unknown Error Code: {:b}", esr.ec);
+        }
+    }
+    println!("-------------------------------------");
+
+    set_return_to_kernel_main();
+}
+
+fn clear_interrupt_for_source(source: IRQSource) {
+    match source {
+        IRQSource::UartInt => clear_uart_interrupt_state(),
+        _ => {
+            todo!()
+        }
+    }
+}
+
+fn set_return_to_kernel_main() {
     unsafe {
-        asm!("ldr x0, =kernel_loop", "msr ELR_EL1, x0");
+        asm!("ldr x0, =kernel_main", "msr ELR_EL1, x0");
         asm!("mov x0, #(0b0101)", "msr SPSR_EL1, x0");
     }
 }
+
+fn handle_gpio_interrupt() {
+    println!("Interrupt");
+    for i in 0..=53u32 {
+        let val = read_gpio_event_detect_status(i);
+
+        if val {
+            #[allow(clippy::single_match)]
+            match i {
+                26 => {
+                    println!("Button Pressed");
+                }
+                _ => {}
+            }
+            // Reset GPIO Interrupt handler by writing a 1
+            reset_gpio_event_detect_status(i);
+        }
+    }
+    unmask_irq();
+}
+
+/// Enables IRQ Source
+pub fn enable_irq_source(state: IRQSource) {
+    let nr = state as u32;
+    let register = ENABLE_IRQ_BASE + 4 * (nr / 32);
+    let register_offset = nr % 32;
+    let current = unsafe { read_address(register) };
+    let mask = 0b1 << register_offset;
+    let new_val = current | mask;
+    unsafe { write_address(register, new_val) };
+}
+
+/// Disable IRQ Source
+pub fn disable_irq_source(state: IRQSource) {
+    let nr = state as u32;
+    let register = DISABLE_IRQ_BASE + 4 * (nr / 32);
+    let register_offset = nr % 32;
+    let current = unsafe { read_address(register) };
+    let mask = 0b1 << register_offset;
+    let new_val = current | mask;
+    unsafe { write_address(register, new_val) };
+}
+
+/// Read current IRQ Source status
+pub fn read_irq_source_status(state: IRQSource) -> u32 {
+    let nr = state as u32;
+    let register = ENABLE_IRQ_BASE + 4 * (nr / 32);
+    let register_offset = nr % 32;
+    (unsafe { read_address(register) } >> register_offset) & 0b1
+}
+
+/// Status if a IRQ Source is pending
+pub fn is_irq_source_pending(state: IRQSource) -> bool {
+    let nr = state as u32;
+    let register = IRQ_PENDING_BASE + 4 * (nr / 32);
+    let register_offset = nr % 32;
+    ((unsafe { read_address(register) } >> register_offset) & 0b1) != 0
+}
+
+/// Status if a IRQ Source is pending
+pub fn get_irq_pending_sources() -> u64 {
+    let mut pending = unsafe { read_address(IRQ_PENDING_BASE + 4) as u64 } << 32;
+    pending |= unsafe { read_address(IRQ_PENDING_BASE) as u64 };
+    pending
+}
+
+#[inline(always)]
+pub fn initialize_interrupt_handler() {
+    unsafe { INTERRUPT_HANDLERS = Some(Vec::new()) };
+}
+
+pub fn register_interrupt_handler(source: IRQSource, function: fn()) {
+    if let Some(handler_vec) = unsafe { &mut *core::ptr::addr_of_mut!(INTERRUPT_HANDLERS) } {
+        handler_vec.push(InterruptHandlers { source, function });
+    }
+}

src/interrupt_handlers/irq.rs

@@ -1,152 +0,0 @@
-use crate::aarch64::registers::read_esr_el1;
-use crate::{
-    aarch64::registers::{
-        daif::{mask_all, unmask_irq},
-        read_exception_source_el,
-    },
-    get_current_el,
-    interrupt_handlers::{
-        DISABLE_IRQ_BASE, ENABLE_IRQ_BASE, GPIO_PENDING_BIT_OFFSET, IRQ_PENDING_BASE,
-    },
-    peripherals::{
-        gpio::{read_gpio_event_detect_status, reset_gpio_event_detect_status},
-        uart::clear_uart_interrupt_state,
-    },
-    read_address, write_address,
-};
-use alloc::vec::Vec;
-use log::{debug, info};
-
-struct InterruptHandlers {
-    source: IRQSource,
-    function: fn(),
-}
-
-// TODO: replace with hashmap and check for better alternatives for option
-static mut INTERRUPT_HANDLERS: Option<Vec<InterruptHandlers>> = None;
-
-#[derive(Clone)]
-#[repr(u32)]
-pub enum IRQSource {
-    AuxInt = 29,
-    I2cSpiSlvInt = 44,
-    Pwa0 = 45,
-    Pwa1 = 46,
-    Smi = 48,
-    GpioInt0 = 49,
-    GpioInt1 = 50,
-    GpioInt2 = 51,
-    GpioInt3 = 52,
-    I2cInt = 53,
-    SpiInt = 54,
-    PcmInt = 55,
-    UartInt = 57,
-}
-
-#[inline(always)]
-pub fn initialize_interrupt_handler() {
-    unsafe { INTERRUPT_HANDLERS = Some(Vec::new()) };
-}
-
-pub fn register_interrupt_handler(source: IRQSource, function: fn()) {
-    if let Some(handler_vec) = unsafe { &mut *core::ptr::addr_of_mut!(INTERRUPT_HANDLERS) } {
-        handler_vec.push(InterruptHandlers { source, function });
-    }
-}
-
-#[no_mangle]
-unsafe extern "C" fn rust_irq_handler() {
-    mask_all();
-    let pending_irqs = get_irq_pending_sources();
-
-    if pending_irqs & GPIO_PENDING_BIT_OFFSET != 0 {
-        handle_gpio_interrupt();
-        let source_el = read_exception_source_el() >> 2;
-        debug!("Source EL: {}", source_el);
-        debug!("Current EL: {}", get_current_el());
-        debug!("Return register address: {:#x}", read_esr_el1());
-    }
-
-    if let Some(handler_vec) = unsafe { &*core::ptr::addr_of_mut!(INTERRUPT_HANDLERS) } {
-        for handler in handler_vec {
-            if (pending_irqs & (1 << (handler.source.clone() as u32))) != 0 {
-                (handler.function)();
-                clear_interrupt_for_source(handler.source.clone());
-            }
-        }
-    }
-}
-
-fn handle_gpio_interrupt() {
-    debug!("GPIO interrupt triggered");
-    for i in 0..=53u32 {
-        let val = read_gpio_event_detect_status(i);
-
-        if val {
-            #[allow(clippy::single_match)]
-            match i {
-                26 => {
-                    info!("Button Pressed");
-                }
-                _ => {}
-            }
-            // Reset GPIO Interrupt handler by writing a 1
-            reset_gpio_event_detect_status(i);
-        }
-    }
-    unmask_irq();
-}
-
-/// Enables IRQ Source
-pub fn enable_irq_source(state: IRQSource) {
-    let nr = state as u32;
-    let register = ENABLE_IRQ_BASE + 4 * (nr / 32);
-    let register_offset = nr % 32;
-    let current = unsafe { read_address(register) };
-    let mask = 0b1 << register_offset;
-    let new_val = current | mask;
-    unsafe { write_address(register, new_val) };
-}
-
-/// Disable IRQ Source
-pub fn disable_irq_source(state: IRQSource) {
-    let nr = state as u32;
-    let register = DISABLE_IRQ_BASE + 4 * (nr / 32);
-    let register_offset = nr % 32;
-    let current = unsafe { read_address(register) };
-    let mask = 0b1 << register_offset;
-    let new_val = current | mask;
-    unsafe { write_address(register, new_val) };
-}
-
-/// Read current IRQ Source status
-pub fn read_irq_source_status(state: IRQSource) -> u32 {
-    let nr = state as u32;
-    let register = ENABLE_IRQ_BASE + 4 * (nr / 32);
-    let register_offset = nr % 32;
-    (unsafe { read_address(register) } >> register_offset) & 0b1
-}
-
-/// Status if a IRQ Source is pending
-pub fn is_irq_source_pending(state: IRQSource) -> bool {
-    let nr = state as u32;
-    let register = IRQ_PENDING_BASE + 4 * (nr / 32);
-    let register_offset = nr % 32;
-    ((unsafe { read_address(register) } >> register_offset) & 0b1) != 0
-}
-
-/// Status if a IRQ Source is pending
-pub fn get_irq_pending_sources() -> u64 {
-    let mut pending = unsafe { read_address(IRQ_PENDING_BASE + 4) as u64 } << 32;
-    pending |= unsafe { read_address(IRQ_PENDING_BASE) as u64 };
-    pending
-}
-
-fn clear_interrupt_for_source(source: IRQSource) {
-    match source {
-        IRQSource::UartInt => clear_uart_interrupt_state(),
-        _ => {
-            todo!()
-        }
-    }
-}

src/interrupt_handlers/synchronous.rs

@@ -1,116 +0,0 @@
-use crate::{
-    aarch64::registers::{daif::mask_all, read_elr_el1, read_esr_el1, read_exception_source_el},
-    get_current_el,
-    interrupt_handlers::{set_return_to_kernel_loop, EsrElX, TrapFrame},
-    pi3::mailbox,
-};
-
-use log::{debug, error, warn};
-
-/// Synchronous Exception Handler
-///
-/// Source is a lower Exception level, where the implemented level
-/// immediately lower than the target level is using
-/// AArch64.
-#[no_mangle]
-unsafe extern "C" fn rust_synchronous_interrupt_imm_lower_aarch64(frame: &mut TrapFrame) -> usize {
-    mask_all();
-    let esr: EsrElX = EsrElX::from(read_esr_el1());
-    debug!("Synchronous interrupt from lower EL triggered");
-    log_sync_exception();
-    match esr.ec {
-        0b100100 => {
-            error!("Data Abort from a lower Exception level");
-            error!("Cause: {}", decode_data_abort(esr.iss as usize));
-        }
-        0b010101 => {
-            debug!("SVC instruction execution in AArch64");
-            return handle_svc(frame);
-        }
-        0b100010 => {
-            error!("PC alignment fault.");
-        }
-        _ => {
-            error!("Synchronous interrupt: Unknown Error Code: {:b}", esr.ec);
-        }
-    }
-
-    warn!("UnhandledException -> Returning to kernel...");
-    set_return_to_kernel_loop();
-    0
-}
-
-fn decode_data_abort(iss: usize) -> &'static str {
-    match iss & 0b111111 {
-        0b000000 => "Address size fault, level 0",
-        0b000001 => "Address size fault, level 1",
-        0b000010 => "Address size fault, level 2",
-        0b000011 => "Address size fault, level 3",
-
-        0b000100 => "Translation fault, level 0",
-        0b000101 => "Translation fault, level 1",
-        0b000110 => "Translation fault, level 2",
-        0b000111 => "Translation fault, level 3",
-
-        0b001001 => "Access flag fault, level 1",
-        0b001010 => "Access flag fault, level 2",
-        0b001011 => "Access flag fault, level 3",
-
-        0b001101 => "Permission fault, level 1",
-        0b001110 => "Permission fault, level 2",
-        0b001111 => "Permission fault, level 3",
-
-        0b010000 => "Synchronous External abort, not on translation table walk",
-        0b011000 => {
-            "Synchronous parity or ECC error on memory access, not on translation table walk"
-        }
-
-        0b010100 => "Synchronous External abort, on translation table walk, level 0",
-        0b010101 => "Synchronous External abort, on translation table walk, level 1",
-        0b010110 => "Synchronous External abort, on translation table walk, level 2",
-        0b010111 => "Synchronous External abort, on translation table walk, level 3",
-
-        0b011100 => "Synchronous parity or ECC error on translation table walk, level 0",
-        0b011101 => "Synchronous parity or ECC error on translation table walk, level 1",
-        0b011110 => "Synchronous parity or ECC error on translation table walk, level 2",
-        0b011111 => "Synchronous parity or ECC error on translation table walk, level 3",
-
-        0b100001 => "Alignment fault",
-        0b110000 => "TLB conflict abort",
-        0b110001 => "Unsupported atomic hardware update fault",
-
-        0b110100 => "IMPLEMENTATION DEFINED fault (Lockdown)",
-        0b110101 => "IMPLEMENTATION DEFINED fault (Unsupported Exclusive or Atomic access)",
-
-        0b111101 => "Section Domain Fault",
-        0b111110 => "Page Domain Fault",
-
-        _ => "Reserved / Unknown",
-    }
-}
-
-fn handle_svc(frame: &mut TrapFrame) -> usize {
-    match frame.x8 {
-        0 => {
-            debug!("Program exited!");
-            set_return_to_kernel_loop();
-            0
-        }
-        67 => {
-            let response = mailbox::read_soc_temp([0]).unwrap();
-            response[1] as usize
-        }
-        _ => 0,
-    }
-}
-
-fn log_sync_exception() {
-    let source_el = read_exception_source_el() >> 2;
-    debug!("--------Sync Exception in EL{}--------", source_el);
-    debug!("Exception escalated to EL {}", get_current_el());
-    debug!("Current EL: {}", get_current_el());
-    let esr: EsrElX = EsrElX::from(read_esr_el1());
-    debug!("{:?}", esr);
-    debug!("Return address: {:#x}", read_elr_el1());
-    debug!("-------------------------------------");
-}

src/lib.rs

@@ -3,13 +3,12 @@
 
 extern crate alloc;
 
+use alloc::boxed::Box;
 use core::{
     arch::asm,
     panic::PanicInfo,
     ptr::{read_volatile, write_volatile},
 };
-use log::LevelFilter;
-use log::{Level, Metadata, Record};
 
 use heap::Heap;
 
@@ -18,13 +17,10 @@ use crate::{
         allocate_memory, PhysSource, KERNEL_VIRTUAL_MEM_SPACE, LEVEL2_BLOCK_SIZE, NORMAL_MEM, UXN,
         WRITABLE,
     },
-    application_manager::initialize_app_manager,
+    interrupt_handlers::initialize_interrupt_handler,
-    console::{flush_terminal, init_terminal},
+    logger::DefaultLogger,
-    interrupt_handlers::irq::initialize_interrupt_handler,
-    pi3::timer::sleep_s,
 };
 
-static LOGGER: UartLogger = UartLogger;
 static PERIPHERAL_BASE: usize = 0x3F00_0000;
 
 unsafe extern "C" {
@@ -34,7 +30,7 @@ unsafe extern "C" {
 #[global_allocator]
 pub static mut GLOBAL_ALLOCATOR: Heap = Heap::empty();
 
-pub unsafe fn initialize_kernel_heap() {
+pub unsafe fn init_kernel_heap() {
     let start = core::ptr::addr_of_mut!(__kernel_end) as usize | KERNEL_VIRTUAL_MEM_SPACE;
     let size = LEVEL2_BLOCK_SIZE * 2;
 
@@ -47,7 +43,6 @@ pub unsafe fn initialize_kernel_heap() {
 fn panic(_panic: &PanicInfo) -> ! {
     loop {
         println!("Panic: {}", _panic.message());
-        sleep_s(1);
     }
 }
 
@@ -57,9 +52,8 @@ pub mod aarch64;
 pub mod configuration;
 pub mod framebuffer;
 pub mod interrupt_handlers;
+pub mod logger;
 
-pub mod application_manager;
-pub mod console;
 pub mod pi3;
 
 #[inline(always)]
@@ -85,33 +79,7 @@ pub fn get_current_el() -> u64 {
 }
 
 pub fn initialize_kernel() {
-    unsafe { initialize_kernel_heap() };
+    unsafe { init_kernel_heap() };
+    logger::set_logger(Box::new(DefaultLogger));
     initialize_interrupt_handler();
-    initialize_app_manager();
-    init_terminal();
-}
-
-struct UartLogger;
-
-impl log::Log for UartLogger {
-    fn enabled(&self, metadata: &Metadata) -> bool {
-        metadata.level() <= Level::Debug
-    }
-
-    fn log(&self, record: &Record) {
-        if self.enabled(record.metadata()) {
-            println!("{} - {}", record.level(), record.args());
-            if record.level() <= Level::Info {
-                flush_terminal();
-            }
-        }
-    }
-
-    fn flush(&self) {}
-}
-
-pub fn init_logger() {
-    log::set_logger(&LOGGER)
-        .map(|()| log::set_max_level(LevelFilter::Debug))
-        .unwrap();
 }

src/logger.rs

@@ -0,0 +1,45 @@
+use core::fmt::Write;
+
+use alloc::{boxed::Box, fmt};
+
+use crate::peripherals::uart;
+
+static mut LOGGER: Option<Box<dyn Logger>> = None;
+
+pub trait Logger: Write + Sync {
+    fn flush(&mut self);
+}
+
+pub struct DefaultLogger;
+
+impl Logger for DefaultLogger {
+    fn flush(&mut self) {}
+}
+
+impl Write for DefaultLogger {
+    fn write_str(&mut self, s: &str) -> core::fmt::Result {
+        uart::Uart.write_str(s)
+    }
+}
+
+#[macro_export]
+macro_rules! log {
+    () => {};
+    ($($arg:tt)*) => {
+        $crate::logger::log(format_args!($($arg)*))
+    };
+}
+
+pub fn log(args: fmt::Arguments) {
+    if let Some(logger) = unsafe { &mut *core::ptr::addr_of_mut!(LOGGER) } {
+        logger.write_str("\n").unwrap();
+        logger.write_fmt(args).unwrap();
+        logger.flush();
+    }
+}
+
+pub fn set_logger(logger: Box<dyn Logger>) {
+    unsafe {
+        LOGGER = Some(logger);
+    }
+}

src/main.rs

@@ -6,18 +6,16 @@ use core::{
     arch::{asm, global_asm},
     ptr::write_volatile,
 };
-use log::{debug, info};
 
 extern crate alloc;
 
-use alloc::{slice, vec::Vec};
+use alloc::vec::Vec;
 use nova::{
     aarch64::registers::{daif, read_id_aa64mmfr0_el1},
-    application_manager::{add_app, Application},
+    configuration::mmu::initialize_mmu_translation_tables,
-    configuration::memory_mapping::initialize_mmu_translation_tables,
     framebuffer::{FrameBuffer, BLUE, GREEN, RED},
-    get_current_el, init_logger,
+    get_current_el,
-    interrupt_handlers::irq::{enable_irq_source, IRQSource},
+    interrupt_handlers::{enable_irq_source, IRQSource},
     peripherals::{
         gpio::{
             blink_gpio, gpio_pull_up, set_falling_edge_detect, set_gpio_function, GPIOFunction,
@@ -25,8 +23,7 @@ use nova::{
         },
         uart::uart_init,
     },
-    pi3::timer::sleep_s,
+    println,
-    print, println,
 };
 
 global_asm!(include_str!("vector.S"));
@@ -36,6 +33,7 @@ static mut FRAMEBUFFER: Option<FrameBuffer> = None;
 
 extern "C" {
     fn el2_to_el1();
+    fn el1_to_el0();
     fn configure_mmu_el1();
     static mut __bss_start: u32;
     static mut __bss_end: u32;
@@ -62,23 +60,24 @@ pub extern "C" fn main() -> ! {
 
     // Set ACT Led to Outout
     let _ = set_gpio_function(21, GPIOFunction::Output);
-    init_logger();
 
-    info!("Hello World!");
+    println!("Hello World!");
-    info!("Current exception level: {}", get_current_el());
+    println!("Exception level: {}", get_current_el());
 
-    info!("initializing MMU...");
+    unsafe {
         initialize_mmu_translation_tables();
-    unsafe { configure_mmu_el1() };
+        configure_mmu_el1();
-    info!("MMU configured!");
+        println!("MMU initialized...");
+    };
 
-    debug!("Register: AA64MMFR0_EL1: {:064b}", read_id_aa64mmfr0_el1());
+    println!("Register: AA64MMFR0_EL1: {:064b}", read_id_aa64mmfr0_el1());
-    info!("Moving El2->EL1");
+    println!("Moving El2->EL1");
     unsafe { FRAMEBUFFER = Some(FrameBuffer::default()) };
 
     unsafe {
         el2_to_el1();
     }
+
     #[allow(clippy::empty_loop)]
     loop {}
 }
@@ -92,50 +91,29 @@ unsafe fn zero_bss() {
 }
 
 #[no_mangle]
-pub extern "C" fn kernel_main() {
+pub extern "C" fn kernel_main() -> ! {
+    println!("Kernel Start...");
     nova::initialize_kernel();
-    info!("Kernel Initialized...");
-    info!("Current exception Level: {}", get_current_el());
-
     let mut test_vector = Vec::new();
     for i in 0..20 {
         test_vector.push(i);
     }
-    debug!("heap allocation test: {:?}", test_vector);
+    println!("heap allocation test: {:?}", test_vector);
-    enable_irq_source(IRQSource::UartInt);
 
-    let app = Application::new(el0 as *const () as usize);
+    println!("Exception Level: {}", get_current_el());
-    add_app(app).unwrap();
-
-    kernel_loop();
-}
-#[no_mangle]
-pub extern "C" fn kernel_loop() {
     daif::unmask_all();
+
+    unsafe {
+        el1_to_el0();
+    };
+
     #[allow(clippy::empty_loop)]
     loop {}
 }
+
 #[no_mangle]
-pub unsafe extern "C" fn el0(argc: usize, argv: *const *const u8) {
+pub extern "C" fn el0() -> ! {
     println!("Jumped into EL0");
-    println!("num: {}", argc);
-    println!("argv: {:?}", argv);
-
-    let raw_args = unsafe { slice::from_raw_parts(argv, argc) };
-    let first_arg = raw_args
-        .iter()
-        .map(|&arg_ptr| {
-            if arg_ptr.is_null() {
-                return "";
-            }
-
-            let c_str = unsafe { core::ffi::CStr::from_ptr(arg_ptr) };
-            let str_slice = c_str.to_str().unwrap();
-            str_slice
-        })
-        .next();
-
-    sleep_s(1);
 
     // Set GPIO 26 to Input
     enable_irq_source(IRQSource::GpioInt0); //26 is on the first GPIO bank
@@ -143,6 +121,8 @@ pub unsafe extern "C" fn el0(argc: usize, argv: *const *const u8) {
     gpio_pull_up(26);
     set_falling_edge_detect(26, true);
 
+    enable_irq_source(IRQSource::UartInt);
+
     if let Some(fb) = unsafe { FRAMEBUFFER.as_mut() } {
         for i in 0..1080 {
             fb.draw_pixel(50, i, BLUE);
@@ -156,32 +136,15 @@ pub unsafe extern "C" fn el0(argc: usize, argv: *const *const u8) {
         fb.draw_function(cos, 0, 101, RED);
     }
 
-    let _temp = syscall(67);
+    loop {
+        // TODO: Mailbox requires a physical address. The stack is now in VA space causing an issue.
+        // Fix with SVCs ?
 
-    if let Some(num) = first_arg.and_then(|val| val.parse::<usize>().ok()) {
+        // let temp = mailbox::read_soc_temp([0]).unwrap();
-        println!("Calculting prime to: {}", num);
+        // println!("{} °C", temp[1] / 1000);
-
-        for i in 3..num {
-            let mut is_prime = true;
-            for j in 3..i {
-                if i == j {
-                    continue;
-                }
-                if i % j == 0 {
-                    is_prime = false;
-                }
-            }
-            if is_prime {
-                print!("{} ", i);
-            }
-        }
-        println!("");
-    } else {
-        println!("Input NaN");
-    }
 
         blink_gpio(SpecificGpio::OnboardLed as u8, 500);
-    syscall(0);
+    }
 }
 
 fn cos(x: u32) -> f64 {
@@ -194,17 +157,3 @@ fn enable_uart() {
     let _ = set_gpio_function(15, GPIOFunction::Alternative0);
     uart_init();
 }
-
-pub fn syscall(nr: u64) -> u64 {
-    let ret: u64;
-
-    unsafe {
-        asm!(
-            "svc #0",
-            in("x8") nr,
-            lateout("x0") ret,
-        );
-    }
-
-    ret
-}

src/pi3/mailbox.rs

@@ -1,9 +1,4 @@
-use core::slice;
+use crate::{read_address, write_address};
-
-use crate::{
-    aarch64::mmu::GRANULARITY, configuration::memory_mapping::MAILBOX_PHYSICAL_ADDRESS,
-    configuration::memory_mapping::MAILBOX_VIRTUAL_ADDRESS, read_address, write_address,
-};
 use nova_error::NovaError;
 
 const MBOX_BASE: u32 = 0x3F00_0000 + 0xB880;
@@ -36,9 +31,8 @@ macro_rules! mailbox_command {
         pub fn $name(
             request_data: [u32; $request_len / 4],
         ) -> Result<[u32; $response_len / 4], NovaError> {
-            let mailbox = unsafe {
+            let mut mailbox =
-                slice::from_raw_parts_mut(MAILBOX_VIRTUAL_ADDRESS as *mut u32, GRANULARITY / 4)
+                [0u32; (HEADER_LENGTH + max!($request_len, $response_len) + FOOTER_LENGTH) / 4];
-            };
             mailbox[0] = (HEADER_LENGTH + max!($request_len, $response_len) + FOOTER_LENGTH) as u32; // Total length in Bytes
             mailbox[1] = 0; // Request
             mailbox[2] = $tag; // Command Tag
@@ -48,9 +42,9 @@ macro_rules! mailbox_command {
             mailbox[5..(5 + ($request_len / 4))].copy_from_slice(&request_data);
             mailbox[(5 + ($request_len / 4))..].fill(0);
 
-            //let addr = core::ptr::addr_of!(mailbox[0]) as u32;
+            let addr = core::ptr::addr_of!(mailbox[0]) as u32;
 
-            write_mailbox(8, unsafe { MAILBOX_PHYSICAL_ADDRESS.unwrap() } as u32);
+            write_mailbox(8, addr);
 
             let _ = read_mailbox(8);
 

src/terminal.rs

@@ -0,0 +1,53 @@
+use core::fmt::Write;
+
+use alloc::string::String;
+use nova::{
+    interrupt_handlers::register_interrupt_handler, logger::Logger,
+    peripherals::uart::read_uart_data, print, println,
+};
+
+pub struct Terminal {
+    buffer: String,
+    input: String,
+}
+
+impl Terminal {
+    pub fn new() -> Self {
+        Self {
+            buffer: String::new(),
+            input: String::new(),
+        }
+    }
+
+    fn flush(&mut self) {
+        println!("{}", self.buffer);
+        print!("> {}", self.input);
+        self.buffer.clear();
+    }
+}
+
+impl Write for Terminal {
+    fn write_str(&mut self, s: &str) -> core::fmt::Result {
+        self.buffer.push_str(s);
+        Ok(())
+    }
+}
+
+impl Logger for Terminal {
+    fn flush(&mut self) {
+        println!("{}", self.buffer);
+        print!("> {}", self.input);
+        self.buffer.clear();
+    }
+}
+
+fn terminal_uart_rx_interrupt_handler() {
+    print!("{}", read_uart_data());
+}
+
+pub fn register_terminal_interrupt_handler() {
+    register_interrupt_handler(
+        nova::interrupt_handlers::IRQSource::UartInt,
+        terminal_uart_rx_interrupt_handler,
+    );
+}

src/vector.S

@@ -1,133 +1,29 @@
-.section .vector_t  , "ax"
+.section .vector_table  , "ax"
 .extern irq_handler
 
 .macro    ventry    label
-.align 7
+.align    11
 b    \label
 .endm
 
 .global vector_table
 vector_table:
-    // Exceptions from current EL using SP_EL0
     ventry .
     ventry .
     ventry .
     ventry .
 
-    // Exceptions from the current EL using SP_ELx
     ventry synchronous_interrupt_no_el_change  // Synchronous Exception  0x200
     ventry irq_handler                // IRQ(Interrupt Request) 0x280
-    ventry .                                        // FIQ(Fast Interrupt Request) 0x300
+    ventry .
-    ventry .                                        // SError 0x580
+    ventry .
 
-    // Exceptions from lower EL AArch64
+    ventry synchronous_interrupt_imm_lower_aarch64
-    ventry synchronous_interrupt_imm_lower_aarch64  // Synchronous Exception 0x400
+    ventry irq_handler
-    ventry irq_handler                              // IRQ(Interrupt Request) 0x480
+    ventry .
-    ventry .                                        //  FIQ(Fast Interrupt Request) 0x500
+    ventry .
-    ventry .                                        // SError 0x580
 
-    // Exceptions from lower EL AArch32
     ventry .
     ventry .
     ventry .
     ventry .
-
-.align 4
-irq_handler:
-    sub sp, sp, #176
-    stp x0, x1, [sp, #0]
-    stp x2, x3, [sp, #16]
-    stp x4, x5, [sp, #32]
-    stp x6, x7, [sp, #48]
-    stp x8, x9, [sp, #64]
-    stp x10, x11, [sp, #80]
-    stp x12, x13, [sp, #96]
-    stp x14, x15, [sp, #112]
-    stp x16, x17, [sp, #128]
-    stp x18, x29, [sp, #144]
-    stp x30, xzr, [sp, #160]
-
-    bl rust_irq_handler
-
-    ldp x0, x1, [sp, #0]
-    ldp x2, x3, [sp, #16]
-    ldp x4, x5, [sp, #32]
-    ldp x6, x7, [sp, #48]
-    ldp x8, x9, [sp, #64]
-    ldp x10, x11, [sp, #80]
-    ldp x12, x13, [sp, #96]
-    ldp x14, x15, [sp, #112]
-    ldp x16, x17, [sp, #128]
-    ldp x18, x29, [sp, #144]
-    ldp x30, xzr, [sp, #160]
-    add sp, sp, #176
-
-    eret
-
-.align 4
-synchronous_interrupt_imm_lower_aarch64:
-    sub sp, sp, #176
-    stp x0, x1, [sp, #0]
-    stp x2, x3, [sp, #16]
-    stp x4, x5, [sp, #32]
-    stp x6, x7, [sp, #48]
-    stp x8, x9, [sp, #64]
-    stp x10, x11, [sp, #80]
-    stp x12, x13, [sp, #96]
-    stp x14, x15, [sp, #112]
-    stp x16, x17, [sp, #128]
-    stp x18, x29, [sp, #144]
-    stp x30, xzr, [sp, #160]
-
-    mov x0, sp
-    bl rust_synchronous_interrupt_imm_lower_aarch64
-    str x0, [sp, #0]
-
-    ldp x0, x1, [sp, #0]
-    ldp x2, x3, [sp, #16]
-    ldp x4, x5, [sp, #32]
-    ldp x6, x7, [sp, #48]
-    ldp x8, x9, [sp, #64]
-    ldp x10, x11, [sp, #80]
-    ldp x12, x13, [sp, #96]
-    ldp x14, x15, [sp, #112]
-    ldp x16, x17, [sp, #128]
-    ldp x18, x29, [sp, #144]
-    ldp x30, xzr, [sp, #160]
-    add sp, sp, #176
-
-    eret
-
-.align 4
-synchronous_interrupt_no_el_change:
-    sub sp, sp, #176
-    stp x0, x1, [sp, #0]
-    stp x2, x3, [sp, #16]
-    stp x4, x5, [sp, #32]
-    stp x6, x7, [sp, #48]
-    stp x8, x9, [sp, #64]
-    stp x10, x11, [sp, #80]
-    stp x12, x13, [sp, #96]
-    stp x14, x15, [sp, #112]
-    stp x16, x17, [sp, #128]
-    stp x18, x29, [sp, #144]
-    stp x30, xzr, [sp, #160]
-
-    mov x0, sp
-    bl rust_synchronous_interrupt_no_el_change
-    str x0, [sp, #0]
-
-    ldp x0, x1, [sp, #0]
-    ldp x2, x3, [sp, #16]
-    ldp x4, x5, [sp, #32]
-    ldp x6, x7, [sp, #48]
-    ldp x8, x9, [sp, #64]
-    ldp x10, x11, [sp, #80]
-    ldp x12, x13, [sp, #96]
-    ldp x14, x15, [sp, #112]
-    ldp x16, x17, [sp, #128]
-    ldp x18, x29, [sp, #144]
-    ldp x30, xzr, [sp, #160]
-    add sp, sp, #176
-
-    eret

tools/start_simulator_debug.sh

@@ -11,4 +11,4 @@ qemu-system-aarch64 \
   -cpu cortex-a53 \
   -serial stdio \
   -sd ../sd.img \
-  -kernel ../target/aarch64-unknown-none/debug/kernel8.img -S -s
+  -kernel ../target/aarch64-unknown-none/debug/kernel8.img \

workspace/heap/src/lib.rs

@@ -39,10 +39,6 @@ impl Heap {
         }
     }
 
-    pub fn size(self) -> usize {
-        self.raw_size
-    }
-
     pub fn init(&mut self, heap_start: usize, heap_end: usize) {
         self.start_address = heap_start as *mut HeapHeader;
         self.end_address = heap_end as *mut HeapHeader;

workspace/heap/src/tests.rs

@@ -29,7 +29,7 @@ fn test_heap_allocation() {
         assert_eq!(actual_alloc_size % MIN_BLOCK_SIZE, 0);
 
         // Verify section is occupied
-        assert!(!(*malloc_header).free);
+        assert!((*malloc_header).free == false);
 
         // Verify next header has been created
         let next = (*malloc_header).next.unwrap();
@@ -55,7 +55,7 @@ fn test_full_heap() {
     let malloc = heap.malloc(malloc_size).unwrap();
     let malloc_header = Heap::get_header_ref_from_data_pointer(malloc);
     unsafe {
-        assert!(!(*malloc_header).free);
+        assert_eq!((*malloc_header).free, false);
         assert!((*malloc_header).next.is_none());
     }
 
@@ -79,7 +79,7 @@ fn test_freeing_root() {
     let malloc = heap.malloc(malloc_size).unwrap();
     let malloc_header = Heap::get_header_ref_from_data_pointer(malloc);
     unsafe {
-        assert!(!(*malloc_header).free);
+        assert_eq!((*malloc_header).free, false);
         assert!((*malloc_header).size >= malloc_size);
         assert!((*root_header).next.is_some());
 

workspace/nova_error/src/lib.rs

@@ -5,12 +5,10 @@ use core::prelude::rust_2024::derive;
 
 #[derive(Debug)]
 pub enum NovaError {
-    General(&'static str),
     Mailbox,
     HeapFull,
     EmptyHeapSegmentNotAllowed,
     Misalignment,
     InvalidGranularity,
-    Paging(&'static str),
+    Paging,
-    OutOfMeomory,
 }