aseg with a working C execution environment

diff --git a/aseg/Makefile b/aseg/Makefile
index f86bc2a203e0c55510c8919bcaa492c12832d884..5bef71f801b5aff0b92f294a65004b985a7f8898 100644 (file)
--- 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 f10955a6f05cd7f7b0b0dd9c4c987ec9c631e503..ee83272652e66bf3595dd8129eecc6c857b2efb3 100644 (file)
--- 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 2d805bb3d373c7e2ae27edf297dcfa6b5751aabb..a3a8ecefbd67d7c97b56b8282e8c063a4abdbdb1 100644 (file)
--- 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 (file)
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);
+}
+