This is a hack for easier testing of GRUB2 in LinuxBIOSv2

since it is still our most wide-spread codebase. 

The patch is pretty trivial, and nobody except Torsten even looked at
it in a week, so....

Signed-off-by: Stefan Reinauer <stepan@coresystems.de>
Acked-by: Stefan Reinauer <stepan@coresystems.de>



git-svn-id: svn://svn.coreboot.org/coreboot/trunk@2880 2b7e53f0-3cfb-0310-b3e9-8179ed1497e1

3 files changed, 871 insertions, 0 deletions

diff --git a/src/mainboard/emulation/qemu-i386/Config.lb b/src/mainboard/emulation/qemu-i386/Config.lb
index ff8fb705ab..72253f7763 100644
--- a/src/mainboard/emulation/qemu-i386/Config.lb
+++ b/src/mainboard/emulation/qemu-i386/Config.lb
@@ -39,6 +39,7 @@ arch i386 end
 ##
 
 driver mainboard.o
+object vgabios.o
 if HAVE_PIRQ_TABLE object irq_tables.o end
 #object reset.o
 
diff --git a/src/mainboard/emulation/qemu-i386/mainboard.c b/src/mainboard/emulation/qemu-i386/mainboard.c
index 497f66eaa4..50ddee1988 100644
--- a/src/mainboard/emulation/qemu-i386/mainboard.c
+++ b/src/mainboard/emulation/qemu-i386/mainboard.c
@@ -1,6 +1,38 @@
+#include <console/console.h>
 #include <device/device.h>
+#include <device/pci.h>
+#include <device/pci_ids.h>
+#include <device/pci_ops.h>
+#include <arch/io.h>
 #include "chip.h"
 
+void vga_enable_console();
+
+static void vga_init(device_t dev)
+{
+	/* code to make vga init run in real mode - does work but against the current Linuxbios philosophy */
+	printk_debug("INSTALL REAL-MODE IDT\n");
+        setup_realmode_idt();
+        printk_debug("DO THE VGA BIOS\n");
+        do_vgabios();
+
+	vga_enable_console();
+}
+
+static struct device_operations vga_operations = {
+	.read_resources   = pci_dev_read_resources,
+	.set_resources    = pci_dev_set_resources,
+	.enable_resources = pci_dev_enable_resources,
+	.init             = vga_init,
+	.ops_pci          = 0,
+};
+
+static struct pci_driver vga_driver __pci_driver = {
+	.ops = &vga_operations,
+	.vendor = 0x1013,
+	.device = 0x00b8,
+};
+
 struct chip_operations mainboard_emulation_qemu_i386_ops = {
 	CHIP_NAME("QEMU Mainboard")
 };
diff --git a/src/mainboard/emulation/qemu-i386/vgabios.c b/src/mainboard/emulation/qemu-i386/vgabios.c
new file mode 100644
index 0000000000..072cb7f21c
--- /dev/null
+++ b/src/mainboard/emulation/qemu-i386/vgabios.c
@@ -0,0 +1,838 @@
+#include <console/console.h>
+#include <device/pci.h>
+#include <device/pci_ids.h>
+#include <device/pci_ops.h>
+#undef __KERNEL__
+#include <arch/io.h>
+#include <string.h>
+
+/* vgabios.c. Derived from: */
+
+/*------------------------------------------------------------ -*- C -*-
+ *  2 Kernel Monte a.k.a. Linux loading Linux on x86
+ *
+ *  Erik Arjan Hendriks <hendriks@lanl.gov>
+ *
+ *  This version is a derivative of the original two kernel monte
+ *  which is (C) 2000 Scyld.
+ *
+ *  Copyright (C) 2000 Scyld Computing Corporation
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, write to the Free Software
+ *  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *
+ * Portions related to the alpha architecture are:
+ *
+ *  Copyright(C) 2001 University of California.  LA-CC Number 01-67.
+ *  This software has been authored by an employee or employees of the
+ *  University of California, operator of the Los Alamos National
+ *  Laboratory under Contract No.  W-7405-ENG-36 with the U.S.
+ *  Department of Energy.  The U.S. Government has rights to use,
+ *  reproduce, and distribute this software. If the software is
+ *  modified to produce derivative works, such modified software should
+ *  be clearly marked, so as not to confuse it with the version
+ *  available from LANL.
+ *
+ *  This software may be used and distributed according to the terms
+ *  of the GNU General Public License, incorporated herein by
+ *  reference to http://www.gnu.org/licenses/gpl.html.
+ *
+ *  This software is provided by the author(s) "as is" and any express
+ *  or implied warranties, including, but not limited to, the implied
+ *  warranties of merchantability and fitness for a particular purpose
+ *  are disclaimed.  In no event shall the author(s) be liable for any
+ *  direct, indirect, incidental, special, exemplary, or consequential
+ *  damages (including, but not limited to, procurement of substitute
+ *  goods or services; loss of use, data, or profits; or business
+ *  interruption) however caused and on any theory of liability,
+ *  whether in contract, strict liability, or tort (including
+ *  negligence or otherwise) arising in any way out of the use of this
+ *  software, even if advised of the possibility of such damage.
+ *
+ *  $Id: vgabios.c,v 1.5 2004/10/06 17:33:52 rminnich Exp $
+ *--------------------------------------------------------------------*/
+
+/* Modified to be a self sufficient plug in so that it can be used 
+   without reliance on other parts of core Linuxbios 
+   (C) 2005 Nick.Barker9@btinternet.com
+
+  Used initially for epia-m where there are problems getting the bios
+  emulator to successfully run this bios.
+*/
+
+/* Declare a temporary global descriptor table - necessary because the
+   Core part of the bios no longer sets up any 16 bit segments */
+__asm__ (
+	/* pointer to original gdt */
+	"gdtarg:			\n"
+	"	.word	gdt_limit	\n"
+	"	.long	gdt	       	\n"		
+
+	/* compute the table limit */
+	"__mygdt_limit = __mygdt_end - __mygdt - 1	\n"
+
+	"__mygdtaddr:			\n"
+	"	.word	__mygdt_limit  	\n"
+	"	.long	__mygdt	       	\n"
+
+	"__mygdt: 		       	\n"
+	/* selgdt 0, unused */
+	"	.word	0x0000, 0x0000	\n"
+	"	.byte	0x00, 0x00, 0x00, 0x00	\n"
+
+	/* selgdt 8, unused */
+	"	.word	0x0000, 0x0000	       	\n"
+	"	.byte	0x00, 0x00, 0x00, 0x00	\n"
+
+	/* selgdt 0x10, flat code segment */
+	"	.word	0xffff, 0x0000	       	\n"
+	"	.byte	0x00, 0x9b, 0xcf, 0x00	\n"	
+
+	/* selgdt 0x18, flat data segment */
+	"	.word	0xffff, 0x0000	       	\n"
+	"	.byte	0x00, 0x93, 0xcf, 0x00	\n"
+
+	/* selgdt 0x20, unused */
+	"	.word	0x0000, 0x0000	       	\n"
+	"	.byte	0x00, 0x00, 0x00, 0x00	\n"
+
+        /* selgdt 0x28 16-bit 64k code at 0x00000000 */
+	"	.word	0xffff, 0x0000	       	\n"
+	"	.byte	0, 0x9a, 0, 0	       	\n"
+
+	/* selgdt 0x30 16-bit 64k data at 0x00000000 */
+	"	.word	0xffff, 0x0000	       	\n"
+	"	.byte	0, 0x92, 0, 0	       	\n"
+
+	"__mygdt_end:				\n"
+);
+
+/* Declare a pointer to where our idt is going to be i.e. at mem zero */
+__asm__ ("__myidt:		\n"
+	 /* 16-bit limit */
+	 "	.word 1023	\n"
+	 /* 24-bit base */
+	 "	.long 0		\n"
+	 "	.word 0		\n"
+);
+
+/* The address arguments to this function are PHYSICAL ADDRESSES */ 
+static void real_mode_switch_call_vga(unsigned long devfn)
+{
+	__asm__ __volatile__ (
+		// paranoia -- does ecx get saved? not sure. This is 
+		// the easiest safe thing to do.
+		"	pushal			\n"
+		/* save the stack */
+		"	mov 	%esp, __stack	\n"
+		"	jmp 	1f		\n"
+		"__stack: .long 0		\n"
+		"1:\n"
+		/* get devfn into %ecx */
+		"	movl    %esp, %ebp	\n"
+		"	movl    8(%ebp), %ecx	\n"
+		/* load 'our' gdt */
+		"	lgdt	%cs:__mygdtaddr	\n"
+
+		/*  This configures CS properly for real mode. */
+		"	ljmp	$0x28, $__rms_16bit\n"
+		"__rms_16bit:		  	\n"
+		"	.code16			\n"
+		/* 16 bit code from here on... */
+
+		/* Load the segment registers w/ properly configured segment
+		 * descriptors.  They will retain these configurations (limits,
+		 * writability, etc.) once protected mode is turned off. */
+		"	mov	$0x30, %ax	\n"
+		"	mov	%ax, %ds       	\n"
+		"	mov	%ax, %es       	\n"
+		"	mov	%ax, %fs       	\n"
+		"	mov	%ax, %gs       	\n"
+		"	mov	%ax, %ss       	\n"
+
+		/* Turn off protection (bit 0 in CR0) */
+		"	movl	%cr0, %eax	\n"
+		"	andl	$0xFFFFFFFE, %eax \n"
+		"	movl	%eax, %cr0	\n"
+
+		/* Now really going into real mode */
+		"	ljmp	$0,  $__rms_real\n"
+		"__rms_real:			\n"
+
+		/* put the stack at the end of page zero. 
+		 * that way we can easily share it between real and protected, 
+		 * since the 16-bit ESP at segment 0 will work for any case. 
+		/* Setup a stack */
+		"	mov	$0x0, %ax	\n"
+		"	mov	%ax, %ss	\n"
+		"	movl	$0x1000, %eax	\n"
+		"	movl	%eax, %esp	\n"
+
+		/* Load our 16 it idt */
+		"	xor	%ax, %ax	\n"
+		"	mov	%ax, %ds	\n"
+		"	lidt	__myidt		\n"
+
+		/* Dump zeros in the other segregs */
+		"	mov	%ax, %es       	\n"
+		"	mov	%ax, %fs       	\n"
+		"	mov	%ax, %gs       	\n"
+		"	mov	$0x40, %ax	\n"
+		"	mov	%ax, %ds	\n"
+		"	mov	%cx, %ax	\n"
+
+		/* run VGA BIOS at 0xc000:0003 */
+		"	lcall	$0xc000, $0x0003\n"
+
+		/* if we got here, just about done. 
+		 * Need to get back to protected mode */
+		"	movl	%cr0, %eax	\n"
+		"	orl	$0x0000001, %eax\n" /* PE = 1 */
+		"	movl	%eax, %cr0	\n"
+
+		/* Now that we are in protected mode jump to a 32 bit code segment. */
+		"	data32	ljmp	$0x10, $vgarestart\n"
+		"vgarestart:\n"
+		"	.code32\n"
+		"	movw	$0x18, %ax     	\n"
+		"	mov	%ax, %ds       	\n"
+		"	mov	%ax, %es	\n"
+		"	mov	%ax, %fs	\n"
+		"	mov	%ax, %gs	\n"
+		"	mov	%ax, %ss	\n"
+
+		/* restore proper gdt and idt */
+		"	lgdt	%cs:gdtarg	\n"
+		"	lidt	idtarg		\n"
+
+		".globl vga_exit		\n"
+		"vga_exit:			\n"
+		"	mov	__stack, %esp	\n"
+		"	popal			\n"
+		);
+}
+
+__asm__ (".text\n""real_mode_switch_end:\n");
+extern char real_mode_switch_end[];
+
+/* call vga bios int 10 function 0x4f14 to enable main console 
+   epia-m does not always autosence the main console so forcing it on is good !! */ 
+void vga_enable_console()
+{
+	__asm__ __volatile__ (
+		/* paranoia -- does ecx get saved? not sure. This is 
+		 * the easiest safe thing to do. */
+		"	pushal			\n"
+		/* save the stack */
+		"	mov	%esp, __stack	\n"
+
+		/* load 'our' gdt */
+		"	lgdt 	%cs:__mygdtaddr	\n"
+
+		/*  This configures CS properly for real mode. */
+		"	ljmp 	$0x28, $__vga_ec_16bit\n"
+		"__vga_ec_16bit:		\n"
+		"	.code16			\n"
+		/* 16 bit code from here on... */
+
+		/* Load the segment registers w/ properly configured segment
+		 * descriptors.  They will retain these configurations (limits,
+		 * writability, etc.) once protected mode is turned off. */
+		"	mov	$0x30, %ax     	\n"
+		"	mov	%ax, %ds       	\n"
+		"	mov	%ax, %es       	\n"
+		"	mov	%ax, %fs       	\n"
+		"	mov	%ax, %gs       	\n"
+		"	mov	%ax, %ss       	\n"
+
+		/* Turn off protection (bit 0 in CR0) */
+		"	movl	%cr0, %eax     	\n"
+		"	andl	$0xFFFFFFFE, %eax\n"
+		"	movl	%eax, %cr0     	\n"
+
+		/* Now really going into real mode */
+		"	ljmp	$0, $__vga_ec_real \n"
+		"__vga_ec_real:                  \n"
+
+		/* put the stack at the end of page zero. 
+		 * that way we can easily share it between real and protected, 
+		 * since the 16-bit ESP at segment 0 will work for any case. 
+		/* Setup a stack */
+		"	mov	$0x0, %ax	\n"
+		"	mov	%ax, %ss	\n"
+		"	movl	$0x1000, %eax	\n"
+		"	movl	%eax, %esp	\n"
+
+		/* debugging for RGM */
+		"	mov	$0x11, %al	\n"
+		"	outb	%al, $0x80	\n"
+
+		/* Load our 16 it idt */
+		"	xor	%ax, %ax       	\n"
+		"	mov	%ax, %ds	\n"
+		"	lidt	__myidt		\n"
+
+		/* Dump zeros in the other segregs */
+		"	mov	%ax, %ds	\n"
+		"	mov	%ax, %es	\n"
+		"	mov	%ax, %fs	\n"
+		"	mov	%ax, %gs	\n"
+
+		/* ask bios to enable main console */
+		/* set up for int 10 call - values found from X server
+		 * bios call routines */
+		//"	movw	$0x4f14,%ax	\n"
+		"	movw	$0x0002,%ax	\n"
+		//"	movw	$0x8003,%bx	\n"
+		"	movw	$1, %cx		\n"
+		"	movw	$0, %dx		\n"
+		"	movw	$0, %di		\n"
+		"	int	$0x10		\n"
+
+		"	movb	$0x55, %al	\n"
+		"	outb	%al, $0x80	\n"
+
+		/* if we got here, just about done. 
+		 * Need to get back to protected mode */
+		"	movl	%cr0, %eax	\n"
+		"	orl	$0x0000001, %eax\n" /* PE = 1 */
+		"	movl	%eax, %cr0	\n"
+
+		/* Now that we are in protected mode jump to a 32 bit code segment. */
+		"	data32	ljmp	$0x10, $vga_ec_restart\n"
+		"vga_ec_restart:\n"
+		"	.code32\n"
+		"	movw	$0x18, %ax	\n"
+		"	mov	%ax, %ds	\n"
+		"	mov	%ax, %es	\n"
+		"	mov	%ax, %fs	\n"
+		"	mov	%ax, %gs	\n"
+		"	mov	%ax, %ss	\n"
+
+		/* restore proper gdt and idt */
+		"	lgdt	%cs:gdtarg 	\n"
+		"	lidt	idtarg		\n"
+		"	.globl	vga__ec_exit	\n"
+		"vga_ec_exit:\n"
+		"	mov	__stack, %esp	\n"
+		"	popal\n"
+		);
+}
+
+void do_vgabios(void)
+{
+	device_t dev;
+	unsigned long busdevfn;
+	unsigned int rom = 0;
+	unsigned char *buf;
+	unsigned int size = 64*1024;
+	int i;
+	
+	/* clear vga bios data area */
+	for (i = 0x400; i < 0x500; i++) {
+		*(unsigned char *) i = 0;
+	}
+
+	dev = dev_find_class(PCI_CLASS_DISPLAY_VGA<<8 , 0);
+
+	if (!dev) {
+		printk_debug("NO VGA FOUND\n");
+		return;
+	}
+	printk_debug("found VGA: vid=%x, did=%x\n", dev->vendor, dev->device);
+
+	/* declare rom address here - keep any config data out of the way
+	 * of core LXB stuff */
+
+	rom = 0xc0000;
+	// pci_write_config32(dev, PCI_ROM_ADDRESS, rom|1);
+	printk_debug("rom base, size: %x\n", rom);
+
+	buf = (unsigned char *) rom;
+	if ((buf[0] == 0x55) && (buf[1] == 0xaa)) {
+		memcpy((void *) 0xc0000, buf, size);
+
+		// write_protect_vgabios();  // in northbridge
+
+	  	// check signature again
+		buf = (unsigned char *) 0xc0000;
+		if (buf[0]==0x55 && buf[1]==0xAA) {
+			busdevfn = (dev->bus->secondary << 8) | dev->path.u.pci.devfn;
+			printk_debug("bus/devfn = %#x\n", busdevfn);
+
+		    	real_mode_switch_call_vga(busdevfn);
+		} else
+			printk_debug("Failed to copy VGA BIOS to 0xc0000\n");
+	} else 
+		printk_debug("BAD SIGNATURE 0x%x 0x%x\n", buf[0], buf[1]);
+
+	pci_write_config32(dev, PCI_ROM_ADDRESS, 0);
+}
+
+
+// we had hoped to avoid this. 
+// this is a stub IDT only. It's main purpose is to ignore calls 
+// to the BIOS. 
+// no longer. Dammit. We have to respond to these.
+struct realidt {
+	unsigned short offset, cs;
+}; 
+
+// from a handy writeup that andrey found.
+
+// handler. 
+// There are some assumptions we can make here. 
+// First, the Top Of Stack (TOS) is located on the top of page zero. 
+// we can share this stack between real and protected mode. 
+// that simplifies a lot of things ...
+// we'll just push all the registers on the stack as longwords, 
+// and pop to protected mode. 
+// second, since this only ever runs as part of linuxbios, 
+// we know all the segment register values -- so we don't save any.
+// keep the handler that calls things small. It can do a call to 
+// more complex code in linuxbios itself. This helps a lot as we don't
+// have to do address fixup in this little stub, and calls are absolute
+// so the handler is relocatable.
+void handler(void)
+{
+	__asm__ __volatile__ ( 
+		"	.code16		\n"
+		"idthandle:		\n"
+		"	pushal		\n"
+		"	movb 	$0, %al	\n"
+		"	ljmp 	$0, $callbiosint16\n"
+		"end_idthandle:		\n"
+		"	.code32		\n"
+		);
+}
+
+void debughandler(void)
+{
+	__asm__ __volatile__ ( 
+		"	.code16		\n"
+		"debughandle:		\n"
+		"	pushw	%cx	\n"
+		"	movw	$250, %cx \n"
+		"dbh1:			\n"
+		"	loop	dbh1	\n"
+		"	popw	%cx	\n"
+		"	iret		\n"
+		"end_debughandle:	\n"
+		".code32		\n"
+		);
+}
+
+// Calling conventions. The first C function is called with this stuff
+// on the stack. They look like value parameters, but note that if you
+// modify them they will go back to the INTx function modified. 
+// the C function will call the biosint function with these as
+// REFERENCE parameters. In this way, we can easily get 
+// returns back to the INTx caller (i.e. vgabios)
+void callbiosint(void)
+{
+	__asm__ __volatile__ (
+		"	.code16		\n"
+		"callbiosint16:		\n"
+		"	push	%ds	\n"
+		"	push	%es	\n"
+		"	push	%fs	\n"
+		"	push	%gs	\n"
+		// clean up the int #. To save space we put it in the lower
+		// byte. But the top 24 bits are junk. 
+		"	andl	$0xff, %eax\n"
+		// this push does two things:
+		// - put the INT # on the stack as a parameter
+		// - provides us with a temp for the %cr0 mods.
+		"	pushl	%eax	\n"
+		"	movl    %cr0, %eax\n"
+		"	orl	$0x00000001, %eax\n" /* PE = 1 */
+		"	movl	%eax, %cr0\n"
+		/* Now that we are in protected mode jump to a 32 bit code segment. */
+		"	data32  ljmp    $0x10, $biosprotect\n"
+		"biosprotect:		\n"
+		"	.code32		\n"
+		"	movw	$0x18, %ax          \n"
+		"	mov	%ax, %ds          \n"
+		"	mov	%ax, %es          \n"
+		"	mov	%ax, %fs          \n"
+		"	mov	%ax, %gs          \n"
+		"	mov	%ax, %ss          \n"
+		"	lidt	idtarg         \n"
+		"	call	biosint	\n"
+		// back to real mode ...
+		"	ljmp	$0x28, $__rms_16bit2\n"
+		"__rms_16bit2:			\n"
+		"	.code16			\n"
+		/* 16 bit code from here on... */
+		/* Load the segment registers w/ properly configured segment
+		 * descriptors.  They will retain these configurations (limits,
+		 * writability, etc.) once protected mode is turned off. */
+		"	mov	$0x30, %ax	\n"
+		"	mov	%ax, %ds	\n"
+		"	mov	%ax, %es	\n"
+		"	mov	%ax, %fs	\n"
+		"	mov	%ax, %gs	\n"
+		"	mov	%ax, %ss	\n"
+		
+		/* Turn off protection (bit 0 in CR0) */
+		"	movl	%cr0, %eax		\n"
+		"	andl	$0xFFFFFFFE, %eax	\n"
+		"	movl	%eax, %cr0		\n"
+
+		/* Now really going into real mode */
+		"	ljmp $0,  $__rms_real2	\n"
+		"__rms_real2:			\n"
+
+		/* Setup a stack
+		 * FixME: where is esp? */
+		"	mov	$0x0, %ax       \n"
+		"	mov	%ax, %ss	\n"
+
+		/* ebugging for RGM */
+		"	mov	$0x11, %al	\n"
+		"	outb	%al, $0x80	\n"
+
+		/* Load our 16 it idt */
+		"	xor	%ax, %ax	\n"
+		"	mov	%ax, %ds	\n"
+		"	lidt	__myidt		\n"
+
+		/* Dump zeros in the other segregs */
+		"	mov	%ax, %es	\n"
+		"	mov	%ax, %fs	\n"
+		"	mov	%ax, %gs	\n"
+		"	mov	$0x40, %ax	\n"
+		"	mov	%ax, %ds	\n"
+
+		/* pop the INT # that you pushed earlier */
+		"	popl	%eax		\n"
+		"	pop	%gs		\n"
+		"	pop	%fs		\n"
+		"	pop	%es		\n"
+		"	pop	%ds		\n"
+		"	popal			\n"
+		"	iret			\n"
+		"	.code32			\n"
+		);
+}
+
+enum {
+	PCIBIOS = 0x1a, 
+	MEMSIZE = 0x12
+};
+
+int pcibios(unsigned long *pedi, unsigned long *pesi, unsigned long *pebp,
+	    unsigned long *pesp, unsigned long *pebx, unsigned long *pedx,
+	    unsigned long *pecx, unsigned long *peax, unsigned long *pflags);
+
+int handleint21(unsigned long *pedi, unsigned long *pesi, unsigned long *pebp,
+		unsigned long *pesp, unsigned long *pebx, unsigned long *pedx,
+		unsigned long *pecx, unsigned long *peax, unsigned long *pflags
+        );
+
+extern void vga_exit(void);
+
+int biosint(unsigned long intnumber,
+	    unsigned long gsfs, unsigned long dses,
+	    unsigned long edi, unsigned long esi,
+	    unsigned long ebp, unsigned long esp, 
+	    unsigned long ebx, unsigned long edx, 
+	    unsigned long ecx, unsigned long eax, 
+	    unsigned long cs_ip, unsigned short stackflags)
+{
+	unsigned long ip; 
+	unsigned long cs; 
+	unsigned long flags;
+	int ret = -1;
+	
+	ip = cs_ip & 0xffff;
+	cs = cs_ip >> 16;
+	flags = stackflags;
+	
+	printk_debug("biosint: INT# 0x%lx\n", intnumber);
+	printk_debug("biosint: eax 0x%lx ebx 0x%lx ecx 0x%lx edx 0x%lx\n", 
+		      eax, ebx, ecx, edx);
+	printk_debug("biosint: ebp 0x%lx esp 0x%lx edi 0x%lx esi 0x%lx\n",
+		     ebp, esp, edi, esi);
+	printk_debug("biosint:  ip 0x%x   cs 0x%x  flags 0x%x\n",
+		     ip, cs, flags);
+
+	// cases in a good compiler are just as good as your own tables. 
+	switch (intnumber) {
+	case 0 ... 15:
+		// These are not BIOS service, but the CPU-generated exceptions
+		printk_info("biosint: Oops, exception %u\n", intnumber);
+		if (esp < 0x1000) {
+			printk_debug("Stack contents: ");
+			while (esp < 0x1000) {
+				printk_debug("0x%04x ", *(unsigned short *) esp);
+				esp += 2;
+			}
+			printk_debug("\n");
+		}
+		printk_debug("biosint: Bailing out\n");
+		// "longjmp"
+		vga_exit();
+		break;
+		
+	case PCIBIOS:
+		ret = pcibios( &edi, &esi, &ebp, &esp, 
+			       &ebx, &edx, &ecx, &eax, &flags);
+		break;
+	case MEMSIZE: 
+		// who cares. 
+		eax = 64 * 1024;
+		ret = 0;
+		break;
+	case 0x15:
+		ret=handleint21( &edi, &esi, &ebp, &esp, 
+				&ebx, &edx, &ecx, &eax, &flags);
+		break;
+	default:
+		printk_info("BIOSINT: Unsupport int #0x%x\n", 
+			    intnumber);
+		break;
+	}
+	if (ret)
+		flags |= 1; // carry flags
+	else
+		flags &= ~1;
+	stackflags = flags;
+	return ret;
+} 
+
+
+void setup_realmode_idt(void) 
+{
+	extern unsigned char idthandle, end_idthandle;
+	extern unsigned char debughandle, end_debughandle;
+
+	int i;
+	struct realidt *idts = (struct realidt *) 0;
+	int codesize = &end_idthandle - &idthandle;
+	unsigned char *intbyte, *codeptr;
+	
+	// for each int, we create a customized little handler
+	// that just pushes %ax, puts the int # in %al, 
+	// then calls the common interrupt handler. 
+	// this necessitated because intel didn't know much about 
+	// architecture when they did the 8086 (it shows)
+	// (hmm do they know anymore even now :-)
+	// obviously you can see I don't really care about memory 
+	// efficiency. If I did I would probe back through the stack
+	// and get it that way. But that's really disgusting.
+	for (i = 0; i < 256; i++) {
+		idts[i].cs = 0;
+		codeptr = (char*) 4096 + i * codesize;
+		idts[i].offset = (unsigned) codeptr;
+		memcpy(codeptr, &idthandle, codesize);
+		intbyte = codeptr + 3;
+		*intbyte = i;
+	}
+	
+	// fixed entry points
+	
+	// VGA BIOSes tend to hardcode f000:f065 as the previous handler of
+	// int10. 
+	// calling convention here is the same as INTs, we can reuse
+	// the int entry code.
+	codeptr = (char*) 0xff065;
+	memcpy(codeptr, &idthandle, codesize);
+	intbyte = codeptr + 3;
+	*intbyte = 0x42; /* int42 is the relocated int10 */
+
+	/* debug handler - useful to set a programmable delay between instructions if the
+	   TF bit is set upon call to real mode */
+	idts[1].cs = 0;
+	idts[1].offset = 16384;
+	memcpy(16384, &debughandle, &end_debughandle - &debughandle);
+
+	
+}
+
+
+
+enum {
+	CHECK = 0xb001,
+	FINDDEV = 0xb102,
+	READCONFBYTE = 0xb108,
+	READCONFWORD = 0xb109,
+	READCONFDWORD = 0xb10a,
+	WRITECONFBYTE = 0xb10b,
+	WRITECONFWORD = 0xb10c,
+	WRITECONFDWORD = 0xb10d
+};
+
+// errors go in AH. Just set these up so that word assigns
+// will work. KISS. 
+enum {
+	PCIBIOS_NODEV = 0x8600,
+	PCIBIOS_BADREG = 0x8700
+};
+
+int
+pcibios(unsigned long *pedi, unsigned long *pesi, unsigned long *pebp, 
+	unsigned long *pesp, unsigned long *pebx, unsigned long *pedx, 
+	unsigned long *pecx, unsigned long *peax, unsigned long *pflags)
+{
+	unsigned long edi = *pedi;
+	unsigned long esi = *pesi;
+	unsigned long ebp = *pebp;
+	unsigned long esp = *pesp;
+	unsigned long ebx = *pebx;
+	unsigned long edx = *pedx;
+	unsigned long ecx = *pecx;
+	unsigned long eax = *peax;
+	unsigned long flags = *pflags;
+	unsigned short func = (unsigned short) eax;
+	int retval = 0;
+	unsigned short devid, vendorid, devfn;
+	short devindex; /* Use short to get rid of gabage in upper half of 32-bit register */
+	unsigned char bus;
+	device_t dev;
+	
+	switch(func) {
+	case  CHECK:
+		*pedx = 0x4350;
+		*pecx = 0x2049;
+		retval = 0;
+		break;
+	case FINDDEV:
+	{
+		devid = *pecx;
+		vendorid = *pedx;
+		devindex = *pesi;
+		dev = 0;
+		while ((dev = dev_find_device(vendorid, devid, dev))) {
+			if (devindex <= 0)
+				break;
+			devindex--;
+		}
+		if (dev) {
+			unsigned short busdevfn;
+			*peax = 0;
+			// busnum is an unsigned char;
+			// devfn is an int, so we mask it off. 
+			busdevfn = (dev->bus->secondary << 8)
+				| (dev->path.u.pci.devfn & 0xff);
+			printk_debug("0x%x: return 0x%x\n", func, busdevfn);
+			*pebx = busdevfn;
+			retval = 0;
+		} else {
+			*peax = PCIBIOS_NODEV;
+			retval = -1;
+		}
+	}
+	break;
+	case READCONFDWORD:
+	case READCONFWORD:
+	case READCONFBYTE:
+	case WRITECONFDWORD:
+	case WRITECONFWORD:
+	case WRITECONFBYTE:
+	{
+		unsigned long dword;
+		unsigned short word;
+		unsigned char byte;
+		unsigned char reg;
+		
+		devfn = *pebx & 0xff;
+		bus = *pebx >> 8;
+		reg = *pedi;
+		dev = dev_find_slot(bus, devfn);
+		if (! dev) {
+			printk_debug("0x%x: BAD DEVICE bus %d devfn 0x%x\n", func, bus, devfn);
+			// idiots. the pcibios guys assumed you'd never pass a bad bus/devfn!
+			*peax = PCIBIOS_BADREG;
+			retval = -1;
+		}
+		switch(func) {
+		case READCONFBYTE:
+			byte = pci_read_config8(dev, reg);
+			*pecx = byte;
+			break;
+		case READCONFWORD:
+			word = pci_read_config16(dev, reg);
+			*pecx = word;
+			break;
+		case READCONFDWORD:
+			dword = pci_read_config32(dev, reg);
+			*pecx = dword;
+			break;
+		case WRITECONFBYTE:
+			byte = *pecx;
+			pci_write_config8(dev, reg, byte);
+			break;
+		case WRITECONFWORD:
+			word = *pecx;
+			pci_write_config16(dev, reg, word);
+			break;
+		case WRITECONFDWORD:
+			dword = *pecx;
+			pci_write_config32(dev, reg, dword);
+			break;
+		}
+		
+		if (retval) 
+			retval = PCIBIOS_BADREG;
+		printk_debug("0x%x: bus %d devfn 0x%x reg 0x%x val 0x%lx\n",
+			     func, bus, devfn, reg, *pecx);
+		*peax = 0;
+		retval = 0;
+	}
+	break;
+	default:
+		printk_err("UNSUPPORTED PCIBIOS FUNCTION 0x%x\n",  func);
+		break;
+	}
+	
+	return retval;
+} 
+
+int handleint21(unsigned long *edi, unsigned long *esi, unsigned long *ebp,
+		unsigned long *esp, unsigned long *ebx, unsigned long *edx,
+		unsigned long *ecx, unsigned long *eax, unsigned long *flags)
+{
+	int res=-1;
+	switch(*eax&0xffff)
+	{
+	case 0x5f19:
+		break;
+	case 0x5f18:
+		*eax=0x5f;
+		*ebx=0x545; // MCLK = 133, 32M frame buffer, 256 M main memory
+		*ecx=0x060;
+		res=0;
+		break;
+	case 0x5f00:
+		*eax = 0x8600;
+		break;
+	case 0x5f01:
+		*eax = 0x5f;
+		*ecx = (*ecx & 0xffffff00 ) | 2; // panel type =  2 = 1024 * 768
+		res = 0;
+		break;
+	case 0x5f02:
+		*eax=0x5f;
+		*ebx= (*ebx & 0xffff0000) | 2;
+		*ecx= (*ecx & 0xffff0000) | 0x401;  // PAL + crt only 
+		*edx= (*edx & 0xffff0000) | 0;  // TV Layout - default
+		res=0;
+		break;
+	case 0x5f0f:
+		*eax=0x860f;
+		break;
+	}
+	return res;
+}