saved_esp: .long 0
saved_ebp: .long 0
+saved_eax: .long 0
+saved_es: .word 0
+saved_ds: .word 0
# drop back to unreal mode to call 16bit interrupt
.global int86
sidt (saved_idtr)
lidt (rmidt)
- # modify the int instruction do this here before the
+ # modify the int instruction. do this here before the
# cs-load jumps, to let them flush the instruction cache
mov $int_op, %ebx
movb 8(%ebp), %al
nop
# load registers from the int86regs struct
+ # point esp to the regs struct to load registers with popa/popf
mov %esp, saved_esp
mov %ebp, saved_ebp
mov 12(%ebp), %esp
popal
+ popfw
+ pop %es
+ pop %ds
+ # ignore fs and gs for now, don't think I'm going to need them
mov saved_esp, %esp
+ # move to the real-mode stack, accessible from ss=0
+ # just in case the BIOS call screws up our unreal mode
+ mov $0x7be0, %esp
+
# call 16bit interrupt
int_op: int $0
+ # BIOS call might have enabled interrupts, cli for good measure
+ cli
- mov saved_ebp, %ebp
- mov 12(%ebp), %esp
- add $34, %esp
- pushfw
- pushal
- mov saved_esp, %esp
+ # save all registers that we'll clobber before having the
+ # chance to populate the int86regs structure
+ mov %eax, saved_eax
+ mov %ds, saved_ds
+ mov %es, saved_es
# re-enable protection
mov %cr0, %eax
mov %ax, %ss
nop
+ # point the esp to our regs struct, to fill it with pusha/pushf
+ mov saved_ebp, %ebp
+ mov 12(%ebp), %esp
+ add $38, %esp
+ mov saved_ds, %ax
+ pushw %ax
+ mov saved_es, %ax
+ pushw %ax
+ pushfw
+ mov saved_eax, %eax
+ pushal
+ mov saved_esp, %esp
+
# restore 32bit interrupt descriptor table
lidt (saved_idtr)
sti
# buffer used by the track loader ... to load tracks.
.align 16
buffer:
+ .global low_mem_buffer
+low_mem_buffer: