Re: [PATCH v3 4/9] PCI/VGA: Improve the default VGA device selection

[suijingfeng]

Hi,

On 2023/7/20 03:32, Bjorn Helgaas wrote:
> > 2) It does not take the PCI Bar may get relocated into consideration.
> > 3) It is not effective for the PCI device without a dedicated VRAM Bar.
> > 4) It is device-agnostic, thus it has to waste the effort to iterate all
> >     of the PCI Bar to find the VRAM aperture.
> > 5) It has invented lots of methods to determine which one is the default
> >     boot device, but this is still a policy because it doesn't give the
> >     user a choice to override.
> I don't think we need a list of*potential*  problems.  We need an
> example of the specific problem this will solve, i.e., what currently
> does not work?


This version do allow the arbitration service works on non-x86 arch,

which also allow me remove a arch-specific workaround.

I will give more detail at the next version.


But I want to provide one more drawback of vgaarb here:


(6) It does not works for non VGA-compatible PCI(e) display controllers.


Because, currently, vgaarb deal with PCI VGA compatible devices only.

See another my patch set [1] for more elaborate discussion.

It also ignore PCI_CLASS_NOT_DEFINED_VGA as Maciej puts it[2].

While my approach do not required the display controller to be 
VGA-compatible to enjoy the arbitration service.

What do you think then?


[1] https://patchwork.freedesktop.org/patch/546690/?series=120548&rev=1

[2] https://lkml.org/lkml/2023/6/18/315