exception 12

exception 12

[Andreas Hasenack]

kernel 2.6.20 vanilla
kvm 14 kernel modules and userspace + "qemu kvm target" patch
everything built with gcc 4

Is this supposed to work? The vdisk.img was created with qemu-img following 
the howto (http://kvm.qumranet.com/kvmwiki/HOWTO). I don't have the iso for a 
boot image, so inserted an ubuntu 6.06 alternate install cd in the drive 
(/dev/cdrom).

# qemu-kvm -hda /qemu/vdisk.img -m 384 -boot d -cdrom /dev/cdrom
exception 12 (0)
rax 0000000000000a9d rbx 0000000000040080 rcx 0000000000002000 rdx 
0000000000012c00
rsi 00000000ffff0800 rdi 0000000000040000 rsp 0000000000087bdc rbp 
0000000000000000
r8  b7fa1fc00d7905c6 r9  00000001b7fa26c8 r10 b7f96992bfb4aa40 r11 
b7b67d90b7fa2880
r12 0000000100000001 r13 08049a7800000000 r14 080fd37000000000 r15 
00000001b7cce3a1
rip 000000000000a4bc rflags 00033206
cs 0000 (00000000/00000000 p 65535 dpl 1 db 3 s 0 type 1 l 3 g 0 avl 0)
ds 0000 (00000000/00000000 p 65535 dpl 1 db 3 s 0 type 1 l 3 g 0 avl 0)
es 0000 (00000000/00000000 p 65535 dpl 1 db 3 s 0 type 1 l 3 g 0 avl 0)
ss 0000 (00000000/00000000 p 65535 dpl 1 db 3 s 0 type 1 l 3 g 0 avl 0)
fs 0000 (00000000/00000000 p 65535 dpl 1 db 3 s 0 type 1 l 3 g 0 avl 0)
gs 0000 (00000000/00000000 p 65535 dpl 1 db 3 s 0 type 1 l 3 g 0 avl 0)
tr 0000 (18850000/00000000 p 8328 dpl 1 db 0 s 0 type 0 l 11 g 0 avl 0)
ldt 0000 (00000000/00000000 p 65535 dpl 1 db 0 s 0 type 0 l 2 g 0 avl 0)
gdt fa4d1/37
idt 0/3ff
cr0 60000010 cr2 0 cr3 0 cr4 0 cr8 0 efer 0
Abortado

For what is worth, it worked with qemu 0.9.0 + kqemu.

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Re: exception 12

[Andreas Hasenack]

On Tuesday 20 February 2007 13:16:00 Andreas Hasenack wrote:
> kernel 2.6.20 vanilla
> kvm 14 kernel modules and userspace + "qemu kvm target" patch
> everything built with gcc 4
>
> Is this supposed to work? The vdisk.img was created with qemu-img following
> the howto (http://kvm.qumranet.com/kvmwiki/HOWTO). I don't have the iso for
> a boot image, so inserted an ubuntu 6.06 alternate install cd in the drive
> (/dev/cdrom).
>
> # qemu-kvm -hda /qemu/vdisk.img -m 384 -boot d -cdrom /dev/cdrom
> exception 12 (0)
> rax 0000000000000a9d rbx 0000000000040080 rcx 0000000000002000 rdx
> 0000000000012c00
> rsi 00000000ffff0800 rdi 0000000000040000 rsp 0000000000087bdc rbp
> 0000000000000000
> r8  b7fa1fc00d7905c6 r9  00000001b7fa26c8 r10 b7f96992bfb4aa40 r11
> b7b67d90b7fa2880
> r12 0000000100000001 r13 08049a7800000000 r14 080fd37000000000 r15
> 00000001b7cce3a1
> rip 000000000000a4bc rflags 00033206
> cs 0000 (00000000/00000000 p 65535 dpl 1 db 3 s 0 type 1 l 3 g 0 avl 0)
> ds 0000 (00000000/00000000 p 65535 dpl 1 db 3 s 0 type 1 l 3 g 0 avl 0)
> es 0000 (00000000/00000000 p 65535 dpl 1 db 3 s 0 type 1 l 3 g 0 avl 0)
> ss 0000 (00000000/00000000 p 65535 dpl 1 db 3 s 0 type 1 l 3 g 0 avl 0)
> fs 0000 (00000000/00000000 p 65535 dpl 1 db 3 s 0 type 1 l 3 g 0 avl 0)
> gs 0000 (00000000/00000000 p 65535 dpl 1 db 3 s 0 type 1 l 3 g 0 avl 0)
> tr 0000 (18850000/00000000 p 8328 dpl 1 db 0 s 0 type 0 l 11 g 0 avl 0)
> ldt 0000 (00000000/00000000 p 65535 dpl 1 db 0 s 0 type 0 l 2 g 0 avl 0)
> gdt fa4d1/37
> idt 0/3ff
> cr0 60000010 cr2 0 cr3 0 cr4 0 cr8 0 efer 0
> Abortado
>
> For what is worth, it worked with qemu 0.9.0 + kqemu.

Forgot the hardware. It's an Intel core 2 duo E6600, runing a 32bits distro.

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Re: exception 12

[Avi Kivity]

Andreas Hasenack wrote:
> kernel 2.6.20 vanilla
> kvm 14 kernel modules and userspace + "qemu kvm target" patch
> everything built with gcc 4
>
> Is this supposed to work? The vdisk.img was created with qemu-img following 
> the howto (http://kvm.qumranet.com/kvmwiki/HOWTO). I don't have the iso for a 
> boot image, so inserted an ubuntu 6.06 alternate install cd in the drive 
> (/dev/cdrom).

This looks like another case of missing real mode emulation on Intel 
hosts.  If you have access to an AMD machine with svm support, you might 
try it on that to confirm.

-- 
error compiling committee.c: too many arguments to function


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Re: exception 12

[Andreas Hasenack]

On Tuesday 20 February 2007 13:54:53 Avi Kivity wrote:
> Andreas Hasenack wrote:
> > kernel 2.6.20 vanilla
> > kvm 14 kernel modules and userspace + "qemu kvm target" patch
> > everything built with gcc 4
> >
> > Is this supposed to work? The vdisk.img was created with qemu-img
> > following the howto (http://kvm.qumranet.com/kvmwiki/HOWTO). I don't have
> > the iso for a boot image, so inserted an ubuntu 6.06 alternate install cd
> > in the drive (/dev/cdrom).
>
> This looks like another case of missing real mode emulation on Intel
> hosts.  If you have access to an AMD machine with svm support, you might
> try it on that to confirm.

I don't, sorry.


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Re: exception 12

[Avi Kivity]

Andreas Hasenack wrote:
>> This looks like another case of missing real mode emulation on Intel
>> hosts.  If you have access to an AMD machine with svm support, you might
>> try it on that to confirm.
>>     
>
> I don't, sorry.
>
>   

Ok.  I'll try it later on.


-- 
error compiling committee.c: too many arguments to function


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Re: exception 12

[Andreas Hasenack]

On Tuesday 20 February 2007 13:54:53 Avi Kivity wrote:
> Andreas Hasenack wrote:
> > kernel 2.6.20 vanilla
> > kvm 14 kernel modules and userspace + "qemu kvm target" patch
> > everything built with gcc 4
> >
> > Is this supposed to work? The vdisk.img was created with qemu-img
> > following the howto (http://kvm.qumranet.com/kvmwiki/HOWTO). I don't have
> > the iso for a boot image, so inserted an ubuntu 6.06 alternate install cd
> > in the drive (/dev/cdrom).
>
> This looks like another case of missing real mode emulation on Intel
> hosts.  If you have access to an AMD machine with svm support, you might

Is this a shortcoming in the Intel implementation? Something serious, i.e., is 
Intel just "playing" with virtualization while AMD has it done correctly?


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Re: exception 12

[Avi Kivity]

Andreas Hasenack wrote:
> On Tuesday 20 February 2007 13:54:53 Avi Kivity wrote:
>   
>> Andreas Hasenack wrote:
>>     
>>> kernel 2.6.20 vanilla
>>> kvm 14 kernel modules and userspace + "qemu kvm target" patch
>>> everything built with gcc 4
>>>
>>> Is this supposed to work? The vdisk.img was created with qemu-img
>>> following the howto (http://kvm.qumranet.com/kvmwiki/HOWTO). I don't have
>>> the iso for a boot image, so inserted an ubuntu 6.06 alternate install cd
>>> in the drive (/dev/cdrom).
>>>       
>> This looks like another case of missing real mode emulation on Intel
>> hosts.  If you have access to an AMD machine with svm support, you might
>>     
>
> Is this a shortcoming in the Intel implementation? Something serious, i.e., is 
> Intel just "playing" with virtualization while AMD has it done correctly?
>
>
>   

The AMD virtualization support makes it fairly easy to support real 
mode.  The Intel implementation requires significant virtual machine 
monitor support for proper real mode.

Real mode has no impact on performance, only on the boot stages.  It's 
certainly incorrect to say Intel is only "playing" with virtualization; 
it's just a design choice of an obscure feature.  But in this particular 
area, Intel has made life hard on VMM developers.

There are other things that are much simpler on the AMD implementation; 
it's generally easier to work with.  Since they've arrived later on the 
scene, they can learn from Intel's mistakes.

Having said all that, the missing real mode support is a kvm bug, not an 
Intel one.  We have to work with whatever the hardware provides and 
supply what it doesn't.

-- 
error compiling committee.c: too many arguments to function


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