Etherboot problems

[Simon Kagstrom <simon.kagstrom-6Uc+yI3S9P8@public.gmane.org>]

Hello!

I'm trying to get etherboot running with KVM (version 2 from today),
but have been unsucessful so far. It works well in plain qemu, but not
with KVM.

I'm running etherboot 5.4.2, ROM rtl8139:rtl8139 [0x10ec,0x8139] built
as a "ISO bootable image without legacy floppy emulation (.iso)" on
http://rom-o-matic.net/5.4.2/. When I run it I get

   $ qemu-system-x86_64 -cdrom ~/eb-rtl8139.iso
   ...
   unhandled vm exit:  0x2
   rax 0000000060000011 rbx 0000000000000e51 rcx 0000000000000000 rdx 0000000000000000
   rsi 0000000000106347 rdi 0000000000016347 rsp 0000000000008fbe rbp 0000000000098fbe
   r8  0000000000000000 r9  0000000000000000 r10 0000000000000000 r11 0000000000000000
   r12 0000000000000000 r13 0000000000000000 r14 0000000000000000 r15 0000000000000000
   rip 0000000000000e8a rflags 00010006
   Aborted

. From browsing the Xen sources, I think the VM exit 0x2 is a
triple-fault. I've disassembled the .iso with hte, and the code that
runs last is

   ...
   00000e75 660fb7ec                       movzx       ebp, sp
   00000e79 6601c5                         add         ebp, eax            
   00000e7c 660f01975200                   lgdt        single ptr [bx+0x52]
   00000e82 0f20c0                         mov         eax, cr0
   00000e85 0c01                           or          al, 0x1
   00000e87 0f22c0                         mov         cr0, eax
   00000e8a 66ffaf6a00                     jmp         far ptr [bx+0x6a]
   ...

I'm not an expert on Intel-syntax 16-bit assembly, but I guess the
last instruction is something like

   jmp  *0x6a(%bx)

. One thing which I'm sure of is if the vm exit was caused by the move
to %cr0 or the jump.

Any takes? I can supply the .iso if someone would like to play with it

// Simon

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