From: Joshua Wise Date: Fri, 5 Sep 2008 21:42:02 +0000 (-0400) Subject: aseg with a working C execution environment X-Git-Url: http://git.joshuawise.com/netwatch.git/commitdiff_plain/4bea7daf0e70a1540b8533c8253c197bb282416e?hp=f54c68a085c376bf5e2d64b50aab28a3f46d0eac aseg with a working C execution environment --- diff --git a/aseg/Makefile b/aseg/Makefile index f86bc2a..5bef71f 100644 --- a/aseg/Makefile +++ b/aseg/Makefile @@ -6,5 +6,5 @@ aseg.bin: aseg.asm aseg.o: aseg.bin objcopy -I binary -B i386 -O elf32-i386 aseg.bin aseg.o -aseg.elf: aseg.bin aseg.lds - ld -o aseg.elf -T aseg.lds \ No newline at end of file +aseg.elf: aseg.bin aseg.lds counter.o + ld -o aseg.elf -T aseg.lds counter.o diff --git a/aseg/aseg.asm b/aseg/aseg.asm index f10955a..ee83272 100644 --- a/aseg/aseg.asm +++ b/aseg/aseg.asm @@ -1,8 +1,6 @@ org 0xA8000 [bits 16] entry: -; mov al, 0x01 ; Say where we are. -; out 0x80, al mov ax, 0xA800 mov ds, ax ; Take us out of flat unreal mode, and mov es, ax ; put us in true real mode. @@ -11,38 +9,25 @@ entry: mov ss, ax jmp 0xA800:(entry2-0xA8000) ; Long jump to a correct cs. entry2: -; mov al, 0x02 -; out 0x80, al lgdt [(gdtr-0xA8000)] ; Set up a new GDT. mov eax, 0x1 mov cr0, eax ; ... and enter pmode! - mov al, 0x03 ; Say we got here. - out 0x80, al jmp long 0x10:continue ; Now longjmp into the new code. [bits 32] continue: -; mov al, 0x04 ; Now we're in protected mode. -; out 0x80, al - mov ax, 0x08 ; Set up segment selectors. mov ds, ax mov es, ax mov fs, ax mov gs, ax mov ss, ax - mov esp, 0x1fffffff + mov esp, [dataptr] -; mov al, 0x05 +; mov al, [cstat] +; add al, 1 ; out 0x80, al - - mov al, [cstat] - add al, 1 - out 0x80, al - mov [cstat], al +; mov [cstat], al - mov eax, 0x11223344 - mov dword [status], eax - mov dx, 0xCF8 ; save off the old config value in dword eax, dx mov [esp-4], eax @@ -85,14 +70,21 @@ continue: mov byte [eax+10], '2' mov byte [eax+11], 0x1F - mov dx, 0x3D4 + mov dx, 0x3D4 ; restore the old stuff mov al, [esp-6] out dx, al - + + mov al, 0 + mov edi, [dataptr+4] ; clear BSS + mov ecx, [dataptr+8] + rep stosb mov dx, 0xCFC ; restore smramc mov al, [esp-5] out dx, al + + mov eax, [dataptr+12] + call eax mov dx, 0xCF8 ; restore the old config value mov eax, [esp-4] @@ -123,8 +115,12 @@ gdt: db 0xFF, 0xFF, 0x00, 0x00, 0x00, 0x9B, 0xCF, 0x00 ; code segment db 0xFF, 0xFF, 0x00, 0x80, 0x0A, 0x9B, 0xCF, 0x00 ; code segment for trampoline -TIMES 512-($-$$) DB 0 -status: - dd 0xAA55AA55 cstat: db 0x00 + +TIMES 512-($-$$) DB 0 +dataptr: + ; 4 bytes of stack top + ; 4 bytes of BSS start + ; 4 bytes of BSS length + ; 4 bytes of C entry point \ No newline at end of file diff --git a/aseg/aseg.lds b/aseg/aseg.lds index 2d805bb..a3a8ece 100644 --- a/aseg/aseg.lds +++ b/aseg/aseg.lds @@ -3,9 +3,27 @@ OUTPUT_ARCH(i386) SECTIONS { . = 0xA8000; - - .aseg 0xA8000 : { + .aseg : { _start = .; aseg.o + LONG(_stacktop); + LONG(_bss); + LONG(_bssend - _bss); + LONG(__start); + *(.text); + *(.data); + *(.rodata); + } + + . = 0x1FF80000; + .bss : { + _bss = .; + *(.bss); + _bssend = .; + } + .stack : { + . = . + 0x10000; + . = ALIGN(0x10); + _stacktop = .; } } diff --git a/aseg/counter.c b/aseg/counter.c new file mode 100644 index 0000000..891c075 --- /dev/null +++ b/aseg/counter.c @@ -0,0 +1,10 @@ +char counter = 0; + +#define outb(port, val) \ +({ asm volatile("outb %0, %%dx" : : "a" ((unsigned char)(val)) , "d" ((unsigned short)(port))); }) + +void __start (void) { + counter++; + outb (0x80, counter); +} +