Re: [PATCH] MdeModulePkg/PciBusDxe: make BAR degradation dependent on OPROM presence

[Ard Biesheuvel <ard.biesheuvel@linaro.org>]

On 12 September 2016 at 14:41, Ni, Ruiyu <ruiyu.ni@intel.com> wrote:
> You could use IncompatiblePciDevice protocol. If you have no clue I will
> give you more information my tomorrow.
>

That works around the problem, but does not solve it. MdeModulePkg is
supposed to be generic/universal, and still, it contains a Intel/CSM
specific hack to degrade 64-bit BARs of any device that has an option
ROM. This is platform specific policy that does not belong in generic
code, and by the same reasoning that Jiewen argues that MdeModulePkg
should not depend on IntelFrameworkModulePkg, it should not implement
legacy BIOS hacks.

So what would you propose to factor out this functionality? Perhaps a
PciPolicyLib, whose Null implementation does not contain the hack. Or
a feature PCD that can be set to disable this behavior?

In any case, the requirement to implement the IncompatiblePciDevice
protocol to get normal resource allocation behavior is not the best
way to deal with this IMO

Thanks,
Ard.