Re: Enabling TPM support in ovmf & hang during qemu boot

[Laszlo Ersek <lersek@redhat.com>]

On 11/12/17 20:09, Marc-André Lureau wrote:
> Hi,
> 
> I use the attached patch to build OVMF with TPM support.
> 
> Even without any TPM device configured (with the following qemu
> command line) the VM hangs early:
> 
> qemu-system-x86_64 -enable-kvm -m 1024 -global
> isa-debugcon.iobase=0x402 -debugcon file:ovmf.log -drive
> if=pflash,format=raw,file=...src/edk2/Build/OvmfX64/DEBUG_GCC5/FV/OVMF_CODE.fd,readonly
> -drive if=pflash,format=raw,file=...src/edk2/Build/OvmfX64/DEBUG_GCC5/FV/OVMF_VARS.fd
> 
> I don't have much clue how to debug OVMF, but adding DEBUG lines, I
> could learn that during ReserveEmuVariableNvStore(), GetNextHob() runs
> an infinite loop, looking for EFI_HOB_TYPE_UNUSED.
> 
> How is the HobList populated? Is it possible to add more of the UNUSED entries?
> 
> Any help welcome
> 

* Neither Tcg2ConfigPei nor Tcg2Pei depend, in their INF files' [depex]
section, on "permanent RAM has been discovered" (=
gEfiPeiMemoryDiscoveredPpiGuid). This means that they can be dispatched
before OvmfPkg/PlatformPei installs the permanent PEI RAM. Therefore, if
they call PeiServicesAllocatePages(), the allocation likely runs out of
the -- very small -- termporary PEI RAM that we have in OVMF.

The way to mitigate this is either to increase the temp PEI RAM (I
already have such a set on the list, but for different purposes -- and
this approach only works if the needed memory is really small), or to
make both of these PEIMs dependent on gEfiPeiMemoryDiscoveredPpiGuid. I
can't say -- Jiewen, would it be OK to make these PEIMs dependent on
gEfiPeiMemoryDiscoveredPpiGuid?


* Both PEIMs depend on PEI-phase read-only variable access
(gEfiPeiReadOnlyVariable2PpiGuid). However, OVMF does not include the
required drivers at the moment -- see
<https://bugzilla.tianocore.org/show_bug.cgi?id=386>. I had posted a
series for that back in ~March 2017, but Jordan disagreed with them. (I
think each of us remains unconvinced by the other's points, from the
original thread.)

Thanks
Laszlo