gamma.ld

TARGET(elf32-i386)

INPUT(beta.o) /* assembly stage1 */
INPUT(gamma.o)  /* rust code */

OUTPUT_ARCH(i386)
OUTPUT_FORMAT("binary")

SECTIONS
{
    /DISCARD/ : {
        * (.eh_frame)
    }

    text 0x7c00 :
    {
        beta.o (*) /* other assembly file, not related */
        gamma.o (.text.rust_boot) /* put this symbol first */
        gamma.o (*)
    }
}

gamma.rs

// Note: using Steve Klabnik's floating point free libcore https://github.com/intermezzOS/libcore/
// Libcore compiled with:
//   cargo rustc --release --target i686-unknown-linux-gnu -- -C panic=abort
// Compiled with
//   rustc --target i686-unknown-linux-gnu -C opt-level=3 -o bin/boot/gamma.o src/boot/gamma.rs -L libcore/target/i686-unknown-linux-gnu/release/ -C relocation-model=static -C panic=abort
//
// Linker output
//   vos/bin/boot//gamma.o(gamma.0.o): In function `rust_boot': gamma.0.rs:(.text.rust_boot+0x86): undefined reference to `core::panicking::panic_bounds_check::ha826e5548fbc34dd'

#![crate_type="lib"]
#![feature(lang_items, asm, intrinsics, core_panic)]
#![no_std]

#[no_mangle]
pub fn rust_boot() -> ! {
    unsafe {
        let mut vga = ::core::slice::from_raw_parts_mut(0xb8000 as *mut u16, 80*25);

        for bg in 0..16 {
            for fg in 0..16 {
                let index = (bg * 80 + fg) as usize;
                vga[index] = (bg << 12) | (fg << 8) | ('a' as u16);
            }
        }
    }

    // prevent CPU executing past this point
    // anything beyond this is likely an invalid instruction sequence
    loop {}
}



// all of this is required due to no libstd
pub mod lang {
    use core::fmt;
    #[no_mangle]
    pub fn __morestack() {}

    #[lang = "panic_fmt"]
    #[no_mangle]
    pub extern fn rust_begin_panic(msg: fmt::Arguments,
                                   file: &'static str,
                                   line: u32) -> ! {
        loop {}
    }
    #[lang="eh_personality"]
    fn eh_personality() {}
}

gamma.symbols

In archive bin/boot/gamma.o:

gamma.0.o:     file format elf32-i386
rw-r--r-- 0/0   1444 Dec 31 19:00 1969 gamma.0.o
architecture: i386, flags 0x00000011:
HAS_RELOC, HAS_SYMS
start address 0x00000000

Sections:
Idx Name          Size      VMA       LMA       File off  Algn
  0 .text         00000000  00000000  00000000  00000034  2**2
                  CONTENTS, ALLOC, LOAD, READONLY, CODE
  1 .text.rust_boot 0000008a  00000000  00000000  00000040  2**4
                  CONTENTS, ALLOC, LOAD, RELOC, READONLY, CODE
  2 .text.__morestack 00000001  00000000  00000000  000000d0  2**4
                  CONTENTS, ALLOC, LOAD, READONLY, CODE
  3 .text.rust_begin_unwind 00000002  00000000  00000000  000000e0  2**4
                  CONTENTS, ALLOC, LOAD, READONLY, CODE
  4 .text.rust_eh_personality 00000001  00000000  00000000  000000f0  2**4
                  CONTENTS, ALLOC, LOAD, READONLY, CODE
  5 .rodata.str2398 00000011  00000000  00000000  00000100  2**4
                  CONTENTS, ALLOC, LOAD, READONLY, DATA
  6 .rodata.panic_bounds_check_loc2399 0000000c  00000000  00000000  00000114  2**2
                  CONTENTS, ALLOC, LOAD, RELOC, READONLY, DATA
  7 .note.GNU-stack 00000000  00000000  00000000  00000120  2**0
                  CONTENTS, READONLY
  8 .eh_frame     00000040  00000000  00000000  00000120  2**2
                  CONTENTS, ALLOC, LOAD, RELOC, READONLY, DATA
SYMBOL TABLE:
00000000 l    df *ABS*	00000000 gamma.0.rs
00000000 l     O .rodata.panic_bounds_check_loc2399	0000000c panic_bounds_check_loc2399
00000000 l     O .rodata.str2398	00000011 str2398
00000000 l    d  .text.rust_boot	00000000 .text.rust_boot
00000000 l    d  .rodata.str2398	00000000 .rodata.str2398
00000000 l    d  .rodata.panic_bounds_check_loc2399	00000000 .rodata.panic_bounds_check_loc2399
00000000         *UND*	00000000 _ZN4core9panicking18panic_bounds_check17ha826e5548fbc34ddE
00000000 g     F .text.__morestack	00000001 __morestack
00000000 g     F .text.rust_begin_unwind	00000002 rust_begin_unwind
00000000 g     F .text.rust_boot	0000008a rust_boot
00000000 g     F .text.rust_eh_personality	00000001 rust_eh_personality



Disassembly of section .text.rust_boot:

00000000 <rust_boot>:
   0:	55                   	push   ebp
   1:	53                   	push   ebx
   2:	57                   	push   edi
   3:	56                   	push   esi
   4:	83 ec 0c             	sub    esp,0xc
   7:	31 c0                	xor    eax,eax
   9:	0f 1f 80 00 00 00 00 	nop    DWORD PTR [eax+0x0]
  10:	66 89 c1             	mov    cx,ax
  13:	8d 41 01             	lea    eax,[ecx+0x1]
  16:	0f b7 d1             	movzx  edx,cx
  19:	c1 e1 0c             	shl    ecx,0xc
  1c:	c1 e2 04             	shl    edx,0x4
  1f:	8d 14 92             	lea    edx,[edx+edx*4]
  22:	31 f6                	xor    esi,esi
  24:	31 ff                	xor    edi,edi
  26:	66 2e 0f 1f 84 00 00 	nop    WORD PTR cs:[eax+eax*1+0x0]
  2d:	00 00 00 
  30:	8d 1c 17             	lea    ebx,[edi+edx*1]
  33:	0f b7 db             	movzx  ebx,bx
  36:	81 fb cf 07 00 00    	cmp    ebx,0x7cf
  3c:	77 34                	ja     72 <rust_boot+0x72>
  3e:	47                   	inc    edi
  3f:	89 f5                	mov    ebp,esi
  41:	09 cd                	or     ebp,ecx
  43:	83 cd 61             	or     ebp,0x61
  46:	66 89 ac 1b 00 80 0b 	mov    WORD PTR [ebx+ebx*1+0xb8000],bp
  4d:	00 
  4e:	81 c6 00 01 00 00    	add    esi,0x100
  54:	0f b7 df             	movzx  ebx,di
  57:	83 fb 10             	cmp    ebx,0x10
  5a:	72 d4                	jb     30 <rust_boot+0x30>
  5c:	0f b7 c8             	movzx  ecx,ax
  5f:	83 f9 0f             	cmp    ecx,0xf
  62:	76 ac                	jbe    10 <rust_boot+0x10>
  64:	66 66 66 2e 0f 1f 84 	data16 data16 nop WORD PTR cs:[eax+eax*1+0x0]
  6b:	00 00 00 00 00 
  70:	eb fe                	jmp    70 <rust_boot+0x70>
  72:	89 5c 24 04          	mov    DWORD PTR [esp+0x4],ebx
  76:	c7 44 24 08 d0 07 00 	mov    DWORD PTR [esp+0x8],0x7d0
  7d:	00 
  7e:	c7 04 24 00 00 00 00 	mov    DWORD PTR [esp],0x0
			81: R_386_32	.rodata.panic_bounds_check_loc2399
  85:	e8 fc ff ff ff       	call   86 <rust_boot+0x86>
			86: R_386_PC32	_ZN4core9panicking18panic_bounds_check17ha826e5548fbc34ddE

Disassembly of section .text.__morestack:

00000000 <__morestack>:
   0:	c3                   	ret    

Disassembly of section .text.rust_begin_unwind:

00000000 <rust_begin_unwind>:
   0:	eb fe                	jmp    0 <rust_begin_unwind>

Disassembly of section .text.rust_eh_personality:

00000000 <rust_eh_personality>:
   0:	c3                   	ret