Re: [RFC PATCH] OvmfPkg/OvmfXen: set PcdAcpiS3Enable at initialization

["Anthony PERARD" <anthony.perard@citrix.com>]

On Thu, Jul 08, 2021 at 12:05:49PM +0800, Gary Lin wrote:
> There are several functions in OvmfPkg/Library using
> QemuFwCfgS3Enabled() to detect the S3 support status. However, in
> MdeModulePkg, PcdAcpiS3Enable is used to check S3 support. Since
> InitializeXenPlatform() didn't set PcdAcpiS3Enable as
> InitializePlatform() did, this made the inconsistency between
> drivers/functions.
> 
> For example, S3SaveStateDxe checked PcdAcpiS3Enable and skipped
> S3BootScript because the default value is FALSE. On the other hand,
> PlatformBootManagerBeforeConsole() from OvmfPkg/Library called
> QemuFwCfgS3Enabled() and found it returned TRUE, so it invoked
> SaveS3BootScript(). However, S3SaveStateDxe skipped S3BootScript, so
> SaveS3BootScript() asserted due to EFI_NOT_FOUND.
> 
> Setting PcdAcpiS3Enable at InitializeXenPlatform() "fixes" the crash
> reported by my colleague. The other possible direction is to replace
> QemuFwCfgS3Enabled() with PcdAcpiS3Enable. I'm not sure which one is
> the right fix.

QemuFwCfgS3Enabled() should always return false as we don't enable
QEMU's fwcfg interface in most case when running a Xen guest. So I don't
expect "PcdAcpiS3Enable" to ever been set via this patch.

Now, maybe we want to set PcdAcpiS3Enable unconditionally but I don't
know if S3 support is going to work as expected with OVMF under Xen, I
never look at that.

What kind of guest are you trying to fix? When does the crash happen?

Thanks,

-- 
Anthony PERARD