stupid old pc. Have to add idt for vga bios.

src/arch/i386/lib/hardwaremain.c

@@ -320,6 +320,10 @@ void hardwaremain(int boot_complete)
 	/* make certain we are the only cpu running in linuxBIOS */
 	wait_for_other_cpus();
 
+#if CONFIG_VGABIOS == 1
+	printk_debug("DO THE VGA BIOS\n");
+	do_vgabios();
+#endif
 	/* Now that we have collected all of our information
 	 * write our configuration tables.
 	 */

src/arch/i386/lib/idt.c

@@ -0,0 +1,132 @@
+// we had hoped to avoid this. 
+#if 0
+/*
+ *  setup_idt
+ *
+ *  sets up a idt with 256 entries pointing to
+ *  ignore_int, interrupt gates. It doesn't actually load
+ *  idt - that can be done only after paging has been enabled
+ *  and the kernel moved to PAGE_OFFSET. Interrupts
+ *  are enabled elsewhere, when we can be relatively
+ *  sure everything is ok.
+ */
+setup_idt:
+	lea ignore_int,%edx
+	movl $(__KERNEL_CS << 16),%eax
+	movw %dx,%ax		/* selector = 0x0010 = cs */
+	movw $0x8E00,%dx	/* interrupt gate - dpl=0, present */
+
+	lea SYMBOL_NAME(idt_table),%edi
+	mov $256,%ecx
+rp_sidt:
+	movl %eax,(%edi)
+	movl %edx,4(%edi)
+	addl $8,%edi
+	dec %ecx
+	jne rp_sidt
+	ret
+
+ENTRY(stack_start)
+	.long SYMBOL_NAME(init_task_union)+8192
+	.long __KERNEL_DS
+
+/* This is the default interrupt "handler" :-) */
+int_msg:
+	.asciz "Unknown interrupt\n"
+	ALIGN
+ignore_int:
+	cld
+	pushl %eax
+	pushl %ecx
+	pushl %edx
+	pushl %es
+	pushl %ds
+	movl $(__KERNEL_DS),%eax
+	movl %eax,%ds
+	movl %eax,%es
+	pushl $int_msg
+	call SYMBOL_NAME(printk)
+	popl %eax
+	popl %ds
+	popl %es
+	popl %edx
+	popl %ecx
+	popl %eax
+	iret
+
+/*
+ * The interrupt descriptor table has room for 256 idt's,
+ * the global descriptor table is dependent on the number
+ * of tasks we can have..
+ */
+#define IDT_ENTRIES	256
+#define GDT_ENTRIES	(__TSS(NR_CPUS))
+
+
+.globl SYMBOL_NAME(idt)
+.globl SYMBOL_NAME(gdt)
+
+	ALIGN
+	.word 0
+idt_descr:
+	.word IDT_ENTRIES*8-1		# idt contains 256 entries
+SYMBOL_NAME(idt):
+	.long SYMBOL_NAME(idt_table)
+
+	.word 0
+#endif
+
+/*
+ * This starts the data section. Note that the above is all
+ * in the text section because it has alignment requirements
+ * that we cannot fulfill any other way.
+ */
+.data
+
+ALIGN
+/*
+ * This contains typically 140 quadwords, depending on NR_CPUS.
+ *
+ * NOTE! Make sure the gdt descriptor in head.S matches this if you
+ * change anything.
+ */
+ENTRY(gdt_table)
+	.quad 0x0000000000000000	/* NULL descriptor */
+	.quad 0x0000000000000000	/* not used */
+	.quad 0x00cf9a000000ffff	/* 0x10 kernel 4GB code at 0x00000000 */
+	.quad 0x00cf92000000ffff	/* 0x18 kernel 4GB data at 0x00000000 */
+	.quad 0x00cffa000000ffff	/* 0x23 user   4GB code at 0x00000000 */
+	.quad 0x00cff2000000ffff	/* 0x2b user   4GB data at 0x00000000 */
+	.quad 0x0000000000000000	/* not used */
+	.quad 0x0000000000000000	/* not used */
+	/*
+	 * The APM segments have byte granularity and their bases
+	 * and limits are set at run time.
+	 */
+	.quad 0x0040920000000000	/* 0x40 APM set up for bad BIOS's */
+	.quad 0x00409a0000000000	/* 0x48 APM CS    code */
+	.quad 0x00009a0000000000	/* 0x50 APM CS 16 code (16 bit) */
+	.quad 0x0040920000000000	/* 0x58 APM DS    data */
+	.fill NR_CPUS*4,8,0		/* space for TSS's and LDT's */
+		
+/*
+ * This is to aid debugging, the various locking macros will be putting
+ * code fragments here.  When an oops occurs we'd rather know that it's
+ * inside the .text.lock section rather than as some offset from whatever
+ * function happens to be last in the .text segment.
+ */
+.section .text.lock
+ENTRY(stext_lock)
+#endif
+
+void
+lidt(void *base, unsigned int limit)
+{
+
+  unsigned int i[2];
+
+  i[0] = limit << 16;
+  i[1] = // later
+}
+// this is too awful. 
+}

src/arch/i386/lib/vgabios.c

@@ -75,7 +75,7 @@ static void real_mode_switch_call_vga(void)
       (
        /* Now that our memcpy is done we can get to 16 bit code
 	* segment.  This configures CS properly for real mode. */
-       "    ljmp $0x28, $0x1000-(real_mode_switch_end - __rms_16bit) \n"
+       "    ljmp $0x28, $__rms_16bit\n"
        "__rms_16bit:                 \n"
        ".code16                      \n" /* 16 bit code from here on... */
 
@@ -95,7 +95,7 @@ static void real_mode_switch_call_vga(void)
        "    movl %eax, %cr0        \n"
 
        /* Now really going into real mode */
-       "    ljmp $0, $0x1000-(real_mode_switch_end - __rms_real) \n"
+       "    ljmp $0,  $__rms_real \n"
        "__rms_real:                  \n"
 
        /* Setup a stack */
@@ -172,6 +172,7 @@ do_vgabios(void)
   struct pci_dev *dev;
   unsigned int rom = 0;
   unsigned char *buf;
+  unsigned int size = 64*1024;
   int i;
 
   dev = pci_find_class(PCI_CLASS_DISPLAY_VGA <<8, NULL);
@@ -183,17 +184,20 @@ do_vgabios(void)
   printk_debug("found VGA: vid=%ux, did=%ux\n", dev->vendor, dev->device);
   pci_read_config_dword(dev, PCI_ROM_ADDRESS, &rom);
   // paranoia
-  rom &= ~1;
+  rom = 0xf0000000;
   pci_write_config_dword(dev, PCI_ROM_ADDRESS, rom|1);
   printk_debug("rom base, size: %x\n", rom);
   buf = (unsigned char *) rom;
-  memcpy((void *) 0xc0000, buf, 64*1024);
+  if ((buf[0] == 0x55) && (buf[1] = 0xaa)) {
+  	memcpy((void *) 0xc0000, buf, size);
 
-  for(i = 0; i < 16; i++)
-    printk_debug("0x%x ", buf[i]);
-  pci_write_config_dword(dev, PCI_ROM_ADDRESS, rom);
-  // check signature here later!
-  real_mode_switch_call_vga();
+  	for(i = 0; i < 16; i++)
+    		printk_debug("0x%x ", buf[i]);
+  	// check signature here later!
+  	real_mode_switch_call_vga();
+  } else 
+	printk_debug("BAD SIGNATURE 0x%x 0x%x\n", buf[0], buf[1]);
+  pci_write_config_dword(dev, PCI_ROM_ADDRESS, 0);
 }
 
 #endif // (CONFIG_VGABIOS == 1)