Re: [Qemu-devel] change x86 default machine type to Q35?

[Laszlo Ersek]

On 07/05/17 08:57, Chao Peng wrote:
> Hi,
>  
> Q35 has been in QEMU for quite a while. Compared to the current default
> i440FX, Q35 is probably not that mature and not widely used, however in
> some case, Q35 has advantages, for example, in supporting new features.
> For instance, we have some features require PCI-e support which is only
> available on Q35 and some others need it for EFI support.

To be a bit more precise: OVMF's default upstream build works fine with
i440fx. But, if you build OVMF with "-D SMM_REQUIRE" -- which is
required for making "-D SECURE_BOOT_ENABLE" actually secure --, then you
do need q35 (the firmware binary won't even boot on i440fx past a
certain point), because only q35 provides SMM emulation.

Thanks
Laszlo

> It is of
> course not necessary to change it as the default but if more and more
> features have dependencies on Q35 because of requiring much more modern
> features then I think it may be worth to do so. In such case we can have
> more people to use it and find problems we may know or not know. There
> are certainly some drawbacks:
> -        Compatibility: current code or script may need adjustment
> -        Quality: we may suffer more bugs on Q35
>  
> Any thoughts?
>  
> Chao
>