Re: kvm guest for 486 sx

[Avi Kivity <avi@redhat.com>]

On 07/07/2009 03:36 PM, Jerry Geis wrote:
>
> Avi Kivity wrote:
>> On 07/07/2009 03:06 PM, Jerry Geis wrote:
>>>> Try -cpu 486,-fpu.
>>>>
>>>
>>> Avi,
>>>
>>> Running this command:
>>> qemu-system-x86_64 -net nic,model=rtl8139 -net user -hda $1 -no-acpi 
>>> -usb -cpu 486,-fpu &
>>>
>>> I get a seg fault:
>>> qemu-system-x86[15419]: segfault at c ip 0000000000458b95 sp 
>>> 0000000041d9df90 error 4 in qemu-system-x86_64[400000+208000]
>>>
>>>
>>> I am running kvm-87 centos 5.3 x86_64.
>>
>> Add -no-kvm-irqchip.  A 486 doesn't have a local APIC, which the code 
>> expects.
>>
> Running with this line:
> qemu-system-x86_64 -net nic,model=rtl8139 -net user -hda $1 -no-acpi 
> -usb -cpu 486,-fpu -no-kvm-irqchip &
>
>
>
> My /proc/cpuinfo shows the follow:
> processor       : 0
> vendor_id       : AuthenticAMD
> cpu family      : 4
> model           : 0
> model name      : 04/00
> stepping        : 0
> fdiv_bug        : no
> hlt_bug         : no
> f00f_bug        : no
> coma_bug        : no
> fpu             : yes
> fpu_exception   : no
> cpuid level     : 0
> wp              : yes
> flags           :
> bogomips        : 2965.50
> clflush size    : 32
> power management:
>
>
> Notice FPU indicates yes and I requested -fpu on the command line.

I think it detects the host fpu as a 487 coprocessor.  Anything in dmesg 
about it?  Note there's no fpu in the flags: line.

That's a kvm kernel bug.

> also is this a 486 as it says AMD?

You can override it if you like, -cpu 486,vendor=AuthenticAMD (I think).

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