* switch happens to the environment below. The magic indicates
* that this is a valid context.
*/
-#ifdef TEST
- .byte 0x55, 0xaa
- .byte 0x80
- .code16
- jmp _start16
-#else
jmp _start
-#endif
.align 8
.long VMXASSIST_MAGIC
.long newctx /* new context */
.long oldctx /* old context */
-#ifdef TEST
-/*
- * We are running in 16-bit. Get into the protected mode as soon as
- * possible. We use our own (minimal) GDT to get started.
- *
- * ROM is a misnomer as this code isn't really rommable (although it
- * only requires a few changes) but it does live in a BIOS ROM segment.
- * This code allows me to debug vmxassists under (a modified version of)
- * Bochs and load it as a "optromimage1".
- */
- .code16
- .globl _start16
-_start16:
- cli
-
- /* load our own global descriptor table */
- data32 addr32 lgdt %cs:(rom_gdtr - TEXTADDR)
-
- /* go to protected mode */
- movl %cr0, %eax
- orl $CR0_PE, %eax
- movl %eax, %cr0
- data32 ljmp $0x08, $1f
-
- .align 32
- .globl rom_gdt
-rom_gdt:
- .word 0, 0 /* 0x00: reserved */
- .byte 0, 0, 0, 0
-
- .word 0xFFFF, 0 /* 0x08: CS 32-bit */
- .byte 0, 0x9A, 0xCF, 0
-
- .word 0xFFFF, 0 /* 0x10: CS 32-bit */
- .byte 0, 0x92, 0xCF, 0
-rom_gdt_end:
-
- .align 4
- .globl rom_gdtr
-rom_gdtr:
- .word rom_gdt_end - rom_gdt - 1
- .long rom_gdt
-
- .code32
-1:
- /* welcome to the 32-bit world */
- movw $0x10, %ax
- movw %ax, %ds
- movw %ax, %es
- movw %ax, %ss
- movw %ax, %fs
- movw %ax, %gs
-
- /* enable Bochs debug facilities */
- movw $0x8A00, %dx
- movw $0x8A00, %ax
- outw %ax, (%dx)
-
- jmp _start
-#endif /* TEST */
-
/*
* This is the real start. Control was transfered to this point
* with CR0_PE set and executing in some 32-bit segment. We call
cli
/* save register parameters to C land */
-#ifdef TEST
- xorl %edx, %edx
-#endif
/* clear bss */
cld
clts
/* setup my own stack */
- movl $stack_top - 4*4, %esp
+ movl $stack_top, %esp
movl %esp, %ebp
/* go ... */
halt:
push $halt_msg
call printf
-#ifdef TEST
- movw $0x8A00, %dx
- movw $0x8AE0, %ax
- outw %ax, (%dx)
-#endif
cli
jmp .
