add basic 32bit support for x86

.cargo/config.toml

@@ -5,11 +5,11 @@ build-std-features = ["compiler-builtins-mem"]
 [build]
 target = "x86_64-eduos.json"
 
-[target.aarch64-eduos]
+[target.i686-eduos]
 rustflags = [
-  "-C", "link-arg=-Tlink_aarch64.ld"
+  "-C", "link-arg=-Tsrc/arch/x86/link_i686.ld", "-C", "relocation-model=static"
 ]
-runner = "qemu-system-aarch64 -display none -serial stdio -machine virt,gic-version=3 -cpu cortex-a72 -semihosting -smp 1 -m 256M --kernel"
+runner = "qemu-system-x86_64 -display none -serial stdio -smp 1 -m 256M --kernel"
 
 [target.x86_64-eduos]
 runner = "bootimage runner"

.github/workflows/run.yml

@@ -46,9 +46,9 @@ jobs:
     - name: Build (x86_64)
       run:
          cargo build
-    - name: Build (aarch64)
+    - name: Build (i686)
       run:
-        cargo build --target=aarch64-eduos.json
+        cargo build --target=i686-eduos.json
     - name: run (ubuntu)
       if: ${{ matrix.os == 'ubuntu-latest' }}
       run: ./test.sh

Cargo.toml

@@ -18,13 +18,9 @@ run-args = []
 [dependencies]
 spinning_top = "0.3.0"
 
-[target.'cfg(target_arch = "aarch64")'.dependencies]
-semihosting = "0.1.9"
-
 [target.'cfg(target_arch = "x86_64")'.dependencies]
 bootloader = "0.9.29"
 x86 = { version = "0.52", default-features = false }
 
-[target.'cfg(target_arch = "wasm32")'.dependencies]
-wasm-bindgen = { version = "0.2.92" }
-web-sys = { version = "0.3.4", features = ['Document','Element','HtmlElement','Node','Window',] }
+[target.'cfg(target_arch = "x86")'.dependencies]
+x86 = { version = "0.52", default-features = false }

i686-eduos.json

@@ -0,0 +1,14 @@
+{
+    "llvm-target": "i686-unknown-none",
+    "target-endian": "little",
+    "target-pointer-width": "32",
+    "target-c-int-width": "32",
+    "os": "none",
+    "arch": "x86",
+    "data-layout": "e-m:e-p:32:32-p270:32:32-p271:32:32-p272:64:64-i128:128-f64:32:64-f80:32-n8:16:32-S128",
+    "features": "-mmx,-sse,+soft-float",
+    "executables": true,
+    "linker-flavor": "ld.lld",
+    "linker": "rust-lld",
+    "panic-strategy": "abort"
+}

src/arch/mod.rs

@@ -1,15 +1,7 @@
 // Export our platform-specific modules.
-#[cfg(target_arch = "x86_64")]
-pub use self::x86_64::{processor, serial};
+#[cfg(any(target_arch = "x86_64", target_arch = "x86"))]
+pub use self::x86::{processor, serial};
 
-// Implementations for x86_64.
-#[cfg(target_arch = "x86_64")]
-pub mod x86_64;
-
-// Export our platform-specific modules.
-#[cfg(target_arch = "x86")]
-pub use self::x86_64::{processor, serial};
-
-// Implementations for x86_64.
-#[cfg(target_arch = "x86")]
-pub mod x86_64;
+// Implementations for x86.
+#[cfg(any(target_arch = "x86_64", target_arch = "x86"))]
+pub mod x86;

src/arch/x86/entry.s

@@ -0,0 +1,53 @@
+# This is the kernel's entry point. We could either call main here,
+# or we can use this to setup the stack or other nice stuff, like
+# perhaps setting up the GDT and segments. Please note that interrupts
+# are disabled at this point: More on interrupts later!
+
+.code32
+
+.set BOOT_STACK_SIZE, 4096
+
+# We use a special name to map this section at the begin of our kernel
+# =>  Multiboot expects its magic number at the beginning of the kernel.
+.section .mboot, "a"
+
+# This part MUST be 4 byte aligned, so we solve that issue using '.align 4'.
+.align 4
+.global mboot
+mboot:
+    # Multiboot macros to make a few lines more readable later
+    .set MULTIBOOT_PAGE_ALIGN,    (1 << 0)
+    .set MULTIBOOT_MEMORY_INFO,   (1 << 1)
+    .set MULTIBOOT_HEADER_MAGIC,  0x1BADB002
+    .set MULTIBOOT_HEADER_FLAGS,  MULTIBOOT_PAGE_ALIGN | MULTIBOOT_MEMORY_INFO
+    .set MULTIBOOT_CHECKSUM,      -(MULTIBOOT_HEADER_MAGIC + MULTIBOOT_HEADER_FLAGS)
+
+    # This is the GRUB Multiboot header. A boot signature
+    .4byte MULTIBOOT_HEADER_MAGIC
+    .4byte MULTIBOOT_HEADER_FLAGS
+    .4byte MULTIBOOT_CHECKSUM
+    .4byte 0, 0, 0, 0, 0 # address fields
+
+.section .text
+.align 4
+.extern main
+.global _start
+_start:
+    cli # avoid any interrupt
+
+    # Initialize stack pointer
+    mov esp, OFFSET boot_stack
+    add esp, BOOT_STACK_SIZE - 16
+
+    call main
+    # eax has the return value of main
+    mov dx, 0xf4 # port to shutdown pc
+    out dx, eax
+L0:
+    jmp L0
+
+.section .data
+.align 4096
+.global boot_stack
+boot_stack:
+    .fill BOOT_STACK_SIZE, 1, 0xcd

src/arch/x86/link_i686.ld

@@ -0,0 +1,26 @@
+ENTRY(_start)
+phys = 0x000000100000;
+
+SECTIONS
+{
+  kernel_start = phys;
+  .mboot phys : AT(ADDR(.mboot)) {
+    *(.mboot)
+  }
+  .text ALIGN(4096) : AT(ADDR(.text)) {
+    *(.text)
+    *(.text.*)
+  }
+  .rodata ALIGN(4096) : AT(ADDR(.rodata)) {
+    *(.rodata)
+    *(.rodata.*)
+  }
+  .data ALIGN(4096) : AT(ADDR(.data)) {
+    *(.data)
+    *(.data.*)
+  }
+  .bss ALIGN(4096) : AT(ADDR(.bss)) {
+    *(.bss)
+    *(.bss.*)
+  }
+}

src/arch/x86/mod.rs

@@ -1,3 +1,7 @@
 pub mod processor;
 pub mod serial;
+#[cfg(target_arch = "x86_64")]
 pub mod start;
+
+#[cfg(target_arch = "x86")]
+core::arch::global_asm!(include_str!("entry.s"));

src/arch/x86/start.rs

@@ -1,4 +1,4 @@
-use crate::arch::x86_64::processor::shutdown;
+use crate::arch::x86::processor::shutdown;
 
 extern "C" {
 	fn main() -> i32;