exception on Intel with kvm-15

["Gregory Haskins" <ghaskins-Et1tbQHTxzrQT0dZR+AlfA@public.gmane.org>]

Hi All,
  I was going to go back to looking at that problem I found a few weeks ago with an unexpected #UD.  However, that test machine was decommisioned so I had to build a new one.  While at it, I started with kvm-15, but now I am seeing this on startup:


# ./qemu-system-x86_64 . -hda ~/kvm/vdisk.img -cdrom /install/SLED-10-DVD-x86_64-GMC-DVD1.iso -boot d -m 512 -L ../pc-bios/
exception 12 (0)
rax 000000000000031e rbx 0000000000040080 rcx 0000000000002000 rdx 0000000000011800
rsi 00000000ffff0800 rdi 0000000000040000 rsp 0000000000087bdc rbp 0000000000000000
r8  0000000000000000 r9  0000000000000000 r10 0000000000000000 r11 0000000000000000
r12 0000000000000000 r13 0000000000000000 r14 0000000000000000 r15 0000000000000000
rip 000000000000a56c rflags 00033206
cs 0000 (00000000/0000ffff p 1 dpl 3 db 0 s 1 type 3 l 0 g 0 avl 0)
ds 0000 (00000000/0000ffff p 1 dpl 3 db 0 s 1 type 3 l 0 g 0 avl 0)
es 0000 (00000000/0000ffff p 1 dpl 3 db 0 s 1 type 3 l 0 g 0 avl 0)
ss 0000 (00000000/0000ffff p 1 dpl 3 db 0 s 1 type 3 l 0 g 0 avl 0)
fs 0000 (00000000/0000ffff p 1 dpl 3 db 0 s 1 type 3 l 0 g 0 avl 0)
gs 0000 (00000000/0000ffff p 1 dpl 3 db 0 s 1 type 3 l 0 g 0 avl 0)
tr 0000 (20850000/00002088 p 1 dpl 0 db 0 s 0 type b l 0 g 0 avl 0)
ldt 0000 (00000000/0000ffff p 1 dpl 0 db 0 s 0 type 2 l 0 g 0 avl 0)
gdt fa4d1/37
idt 0/3ff
cr0 60000010 cr2 0 cr3 0 cr4 0 cr8 0 efer 0
Aborted

I am on a Dell 490 with 2-socket/2-core Xeon 5130s (Woodcrest) on a 2.6.16.21 x86_64 based suse kernel.  I get the SDL window and it appears to blow up on the part of the bios where the drives are displayed.  If I am reading the output correctly, the RIP is at 0xa56c (presumably within Bochs) and took exception 12 (#SS).

First question: does "exception 12" correlate to the Intel #SS, or did I read that wrong.

Second question: Any ideas on whats wrong?

Third question:  How do you guys debug problems early on in the BIOS like this?  I tried using (-S -s) and connecting GDB, but I couldn't figure out how to make it do asm debugging without providing an elf binary since the bios.bin is already stripped and setup with a custom linker.conf.   

Thanks!
-Greg

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