From mboxrd@z Thu Jan  1 00:00:00 1970
From: Avi Kivity <avi@redhat.com>
Subject: Re: [PATCH kvm-unit-tests 07/10] Correct the tss size
Date: Wed, 25 Aug 2010 16:11:22 +0300
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To: Jason Wang <jasowang@redhat.com>
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  On 08/25/2010 04:00 PM, Jason Wang wrote:
>
> 0000000000400bb8<__setup_args>:
>    400bb8:       41 55                   push   %r13
>    400bba:       41 54                   push   %r12
>    400bbc:       55                      push   %rbp
>    400bbd:       53                      push   %rbx
>    400bbe:       48 8b 1d db e7 00 00    mov    0xe7db(%rip),%rbx        # 40f3a0<__args>
>    400bc5:       41 bc 80 ec 40 00       mov    $0x40ec80,%r12d
>    400bcb:       41 bd 80 f0 40 00       mov    $0x40f080,%r13d
>    400bd1:       eb 42                   jmp    400c15<__setup_args+0x5d>
>    400bd3:       4d 89 65 00             mov    %r12,0x0(%r13)
>    400bd7:       0f b6 28                movzbl (%rax),%ebp
>    400bda:       40 84 ed                test   %bpl,%bpl
>    400bdd:       75 16                   jne    400bf5<__setup_args+0x3d>
>    400bdf:       eb 21                   jmp    400c02<__setup_args+0x4a>
>    400be1:       41 88 2c 24             mov    %bpl,(%r12)
>    400be5:       49 83 c4 01             add    $0x1,%r12
>    400bed:       0f b6 2b                movzbl (%rbx),%ebp
>    400bf0:       40 84 ed                test   %bpl,%bpl
>    400bf3:       74 0d                   je     400c02<__setup_args+0x4a>
>    400bf5:       40 0f be fd             movsbl %bpl,%edi
>    400bf9:       e8 a6 ff ff ff          callq  400ba4<isblank>
>    400bfe:       84 c0                   test   %al,%al
>    400c00:       74 df                   je     400be1<__setup_args+0x29>
>    400c02:       49 83 c5 08             add    $0x8,%r13
>    400c06:       41 c6 04 24 00          movb   $0x0,(%r12)
>    400c0b:       49 83 c4 01             add    $0x1,%r12
>    400c0f:       eb 04                   jmp    400c15<__setup_args+0x5d>
>    400c11:       48 83 c3 01             add    $0x1,%rbx
>>> 400c15:       0f b6 2b                movzbl (%rbx),%ebp
>    400c18:       40 0f be fd             movsbl %bpl,%edi
>    400c1c:       e8 83 ff ff ff          callq  400ba4<isblank>
>    ....
>


Looks completely unrelated.  We access the command line string and fault.

You can hack qemu-kvm to vmstop() on KVM_EXIT_SHUTDOWN and examine 
%rbx.  It's probably corrupted.  Maybe we need to copy the multiboot 
command line early to prevent the rest of the code from stomping on it.

-- 
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.