Re: [PATCH 08/10] OvmfPkg: Update Sec to support Tdvf Config-B


Gerd Hoffmann
 

Hi,

I don't see that PEI-less boot is required for that. Sure, when stripping down
the build and removing all the features which require PEIMs there isn't much
left to do for the PEI phase. So it makes sense to look into dropping PEI
altogether. But it's more a "nice to have"
than a hard requirement, no?
No. I have to say PEI-less boot in Config-B is a hard requirement.
I'm still wondering why though. I have not yet seen a reason why
config-b can't use the PEI-based boot flow.

4. But a basic version of PlatformInitLib is a good start.
Yes. Having initially only the functions needed by config-b in PlatformInitLib
is perfectly fine, but this should be a code *move* not a copy.

During the development and community review, we can understand better
what functions should be wrapped into PlatformInitLib. After that
PlatformInitLib can be evolved for OvmfPkg/PlatformPei,
Bhyve/PlatformPei, XenPlatformPei.
Yes, most likely there are a number of opportunities to reduce code
duplication in the three PlatformPei variants we have by moving code to the
(shared) PlatformInitLib.

That can be looked at later.
So let me summarize the discussion about PlatformInitLib.
1. PlatformInitLib wraps the common functions in OvmfPkg/PlatformPei.
These common functions covers the memory detection via fw_cfg, pci
init, cmos, (MemDetect.c/Platform.c/Cmos.c).
Yes. Everything needed for PEI-less / config-b boot moves to
PlatformInitLib.

PlatformInitLib is added as dependency to OvmfPkg/PlatformPei, so
PlatformPei can call those functions when booting with PEI.

PEI-less boot will add PlatformInitLib to SEC (and DXE) instead
so the same code can be used then.

Not sure how to handle cmos best. Not needed for memory detection on
qemu, but cloudhw depends on it so it is back for now. Will cloudhw
support tdx too btw?

And PlatformInitLib will
not handle the S3/SMM variants.
At least not initially. Maybe later when we move more code to the lib
to reduce code duplication in xen/bhyve/qemu PlatformPei variants.

2. OvmfPkg/PlatformPei will be refactored with PlatformInitLib. The
functions not needed by config-b stay in PlatformPei.
3. Config-B support PEI-less boot for both legacy guest and td guest.
Yes.

take care,
Gerd

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