diff options
Diffstat (limited to 'qemu/roms/seabios/vgasrc/vgaentry.S')
| -rw-r--r-- | qemu/roms/seabios/vgasrc/vgaentry.S | 18 |
1 files changed, 16 insertions, 2 deletions
diff --git a/qemu/roms/seabios/vgasrc/vgaentry.S b/qemu/roms/seabios/vgasrc/vgaentry.S index d9ebdb93c..53be2b38c 100644 --- a/qemu/roms/seabios/vgasrc/vgaentry.S +++ b/qemu/roms/seabios/vgasrc/vgaentry.S @@ -86,14 +86,23 @@ entry_10: ENTRY_ARG_VGA handle_10 iretw +#define VGA_CUSTOM_BDA_FLAGS 0xb9 +#define BF_EXTRA_STACK 0x40 + // Entry point using extra stack DECLFUNC entry_10_extrastack entry_10_extrastack: cli cld - pushw %ds // Set %ds:%eax to space on ExtraStack + pushw %ds pushl %eax - movw %cs:ExtraStackSeg, %ds + + movw $SEG_BDA, %ax // Check if extra stack is enabled + movw %ax, %ds + testb $BF_EXTRA_STACK, VGA_CUSTOM_BDA_FLAGS + jz 1f + + movw %cs:ExtraStackSeg, %ds // Set %ds:%eax to space on ExtraStack movl $(CONFIG_VGA_EXTRA_STACK_SIZE-PUSHBREGS_size-16), %eax SAVEBREGS_POP_DSEAX // Save registers on extra stack movl %esp, PUSHBREGS_size+8(%eax) @@ -116,6 +125,11 @@ entry_10_extrastack: RESTOREBREGS_DSEAX iretw +1: // Use regular entry point if the extra stack is disabled + popl %eax + popw %ds + jmp entry_10 + // Timer irq handling DECLFUNC entry_timer_hook entry_timer_hook: |