[coreboot] How can I call the interrupt of SeaBIOS in coreboot?

Zhang Rui zrfail at gmail.com
Tue Aug 5 06:50:54 CEST 2008

	I am blocked with calling interrupt in coreboot.
	I tryed these ways:
	1. use "asm("int $0x19 \n");".  Qemu has no output when executeed
here and nothing happens. The reason is that it should jump to real
mode before calling int 19.

	2. write a function boot_coreboot() in seabios. like:

	void VISIBLE32 boot_coreboot()
		struct bregs br;
		dprintf(1, "boot_coreboot: begin\n");
		memset(&br, 0, sizeof(br));
		dprintf(1, "boot_coreboot: call int 19\n");
		call16_int(0x19, &br);
		dprintf(1, "boot_coreboot: end\n");
	then call boot_coreboot() in seabios. It booted successfully.

	I have read the source code of call16_int, it jump to real mode and
jump to the int 19 handler function directly, but do not use "int
$0x19" asm code. why?

	3. write asm code to jump to real mode and call int 19.
	but in coreboot there is compiling errors when I write asm codes with
lables in it in vm86.c.
	for a simple example:
	__asm__ __volatile__ (
			/* paranoia -- does ecx get saved? not sure. This is
			 * the easiest safe thing to do. */
			"	pushal			\n"
			"	ljmp 	$0x28, $cbint16bit\n"
			"cbint16bit:		\n"
			"	.code16			\n"
			"	popal\n"

	will cause errors:
	{standard input}: Assembler messages:
	{standard input}:746: Error: symbol `cbint16bit' is already defined
	in seabios there is compiling errors because of ".code16":
	out/../src/post.c:349: relocation truncated to fit: R_386_16 against `.text'

	what is wrong here?

2008/7/17, Kevin O'Connor <kevin at koconnor.net>:
> On Thu, Jul 17, 2008 at 09:58:59AM +0800, Zhang Rui wrote:
> [...]
> > If I manually change to 16bit mode then call int19 in coreboot,  will it be OK?
> > If it does, the 16bit mode option rom codes can use the int handler of SeaBIOS?
> It should work.

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