Re: [PATCH 1/2] vfio: Make vfio-pci available on 64-bit host platforms only

["Cédric Le Goater" <clg@redhat.com>]

On 3/3/25 16:26, BALATON Zoltan wrote:
> On Mon, 3 Mar 2025, Cédric Le Goater wrote:
>> On 3/3/25 15:46, Paolo Bonzini wrote:
>>> On 3/3/25 15:30, Philippe Mathieu-Daudé wrote:
>>>>>>> I see PPC is defined in target/ppc/Kconfig so I think these mark the target not the host. Vfio-pci works with qemu-system-ppc 
>>>>>
>>>>> I've seen people do this on x86_64 host
>>>>
>>>> Since this patch does:
>>>>
>>>>    LINUX && PCI && (...  X86_64 ...)
>>>>
>>>> these users won't see any change.
>>>
>>> This is wrong---clearly this patch was never tested on the 32-bit platforms where it was supposed to have an effect.
>>
>> euh it was.
>>
>> With this patch, on 32-bit and 64-bit host systems :
>>
>>  # build/qemu-system-i386 -device vfio-pci,?
>>  # qemu-system-i386: -device vfio-pci,?: Device 'vfio-pci' not found
>>
>> Same for qemu-system-ppc and qemu-system-arm
>>
>> What I am doing wrong ?
> 
> These QEMU targets aren't deprecated, compiling QEMU on 32 bit hosts is. But you can still use qemu-system-i386 and qemu-system-ppc on 64 bit hosts and vfio-pci works with these so it should not be disabled when building these QEMU targets. I think you meant to do something else not what this patch does.

I meant to remove all VFIO devices on 32-bit host platforms (which
is not needed anymore since 32-bit host platforms are dying anyway).

The patch is actually doing more, as it is removing VFIO devices for
32-bit targets too. That said, I doubt this config is tested at all
on i386. Something to add on the TODO list.

Why are we keeping qemu-system-ppc and qemu-system-i386, and arm,
since qemu-system-ppc64 and qemu-system-x86_64 should be able to
run the same machines ?


Thanks,

C.





> 
> Regards,
> BALATON Zoltan