fixed invalid data accesses, due to DS != SS, moved everything into the

first 64k instead, should be enough for the kernel.

diff --git a/kern/Makefile b/kern/Makefile
index d097da2..187df0d 100644 (file)
--- a/kern/Makefile
+++ b/kern/Makefile
@@ -14,8 +14,9 @@ LD = ia16-elf-ld
 
 warn = -pedantic -Wall
 inc = -nostdinc -Isrc -Isrc/libc
+arch = -march=i8088 -mtune=i8088
 
-CFLAGS = -march=i8088 -mtune=i8088 $(warn) $(inc) -MMD
+CFLAGS = $(arch) -ffreestanding -mcmodel=small $(warn) $(inc) -MMD
 LDFLAGS = -T kern.ld -Map kern.map
 
 $(img): $(bin)

diff --git a/kern/src/main.c b/kern/src/main.c
index f89cd5d..cc3cd14 100644 (file)
--- a/kern/src/main.c
+++ b/kern/src/main.c
@@ -3,19 +3,7 @@
 
 void kmain(void)
 {
-       int i, j;
-       unsigned short __far *vmem = (void __far*)0xb8000000ul;
-       unsigned short c;
-
        vid_init();
        vid_text(0, 0, "hello!", VID_ATTR(LTRED, BLACK));
        init_intr();
-
-       vmem += 80;
-       for(i=1; i<25; i++) {
-               c = ((i & 0xf) << 8) | '@';
-               for(j=0; j<80; j++) {
-                       *vmem++ = c;
-               }
-       }
 }

diff --git a/kern/src/startup.asm b/kern/src/startup.asm
index c64684a..2cd9250 100644 (file)
--- a/kern/src/startup.asm
+++ b/kern/src/startup.asm
@@ -3,7 +3,7 @@
        bits 16
        section .startup
 
-; memory reserved at the top of RAM for the kernel stack
+; memory reserved at the top of the kernel segment for the stack
 STACKSZ equ 4096
 
 extern kmain
@@ -14,10 +14,9 @@ global _start
 _start:
        ; TODO floppy off if necessary
 
-       ; move stack to the top of RAM (TODO: detect and avoid Ext. BIOS data area)
-       mov ax, (0xa0000 - STACKSZ) >> 4
-       mov ss, ax
-       mov sp, STACKSZ
+       ; move stack to the top of the kernel segment
+       xor ax, ax
+       mov sp, ax
 
        ; zero .bss
        mov di, _bss_start_off