Re: [edk2-devel] [PATCH 0/4] OvmfPkg/PlatformPei: fix two assertion failures with weird RAM sizes

["Laszlo Ersek" <lersek@redhat.com>]

On 05/15/19 13:56, Leif Lindholm wrote:
> On Wed, May 15, 2019 at 12:36:22PM +0200, Laszlo Ersek wrote:
>> Hi Stewards,
>>
>> it seems likely that this patch series -- posted on 2019-May-04 -- will
>> not receive the necessary maintainer A-b's / R-b's before we enter the
>> soft feature freeze for edk2-stable201905.
>>
>> Therefore I'd like to state that I consider this series a bugfix series,
>> not a feature addition. I'm now asking for confirmation that I'll be
>> allowed to push the series -- dependent on the expected reviewer
>> feedback of course -- even after 2019-May-17 08:00:00 UTC.
> 
> Clearly bugfix, and quite contained in scope as well.
> 
>> Please also state whether I will need to open a TianoCore BZ for
>> tracking this work (and to update the commit messages accordingly). I
>> haven't done that because we already have two public BZs for the issue
>> in the Red Hat Bugzilla instance, with issue description and analysis.
>> (RHBZ references are captured in both the blurb below, and in the
>> patches themselves.)
> 
> I would lean towards having a TianoCore BZ for anything pushed in the
> freeze period.
> 
> While I don't expect Red Hat to close its BZ from public access, it
> does sort of open up the question of "well, which other BZs do we
> consider trustworthy enough to give the same treatment?" that I would
> prefer to avoid having to deal with during future freeze periods.

Good point; I've now filed
<https://bugzilla.tianocore.org/show_bug.cgi?id=1814>, and I'll
reference it in the commit messages, when I push the series.

Thanks!
Laszlo

> But if you (plural) feel I'm being overly cautious, I don't feel
> *that* strongly about it.
> 
> Regards,
> 
> Leif
> 
>> Thanks
>> Laszlo
>>
>> On 05/04/19 02:07, Laszlo Ersek wrote:
>>> Repo:   https://github.com/lersek/edk2.git
>>> Branch: exbar_mtrr_rhbz_1666941
>>> Ref:    https://bugzilla.redhat.com/show_bug.cgi?id=1666941
>>> Ref:    https://bugzilla.redhat.com/show_bug.cgi?id=1701710
>>>
>>> When booting OVMF on QEMU with "weird" RAM sizes, QEMU's low-RAM split
>>> logic can trigger two assertion failures in OVMF:
>>>
>>> - conflict between PCIEXBAR (ECAM) and low-RAM, on q35,
>>>
>>> - running out of variable MTRRs when marking the uncacheable MMIO range
>>>   in 32-bit address space, on both i440fx and q35.
>>>
>>> This series fixes both issues, by moving around the PCIEXBAR on q35, and
>>> by truncating the size of the uncacheable 32-bit area to a power of two.
>>> The latter idea was inspired by SeaBIOS.
>>>
>>> Tested on both machine types, with the following memory sizes (all in
>>> MB): 1025, 2815, 3583, 5120. On i440fx, the X64 build was used (without
>>> SMM). On q35, the IA32 and IA32X64 builds were used (with SMM). Testing
>>> included "/proc/mtrr" verification, 32-bit PCI MMIO aperture
>>> verification, general dmesg checks, and my usual regression tests too
>>> (ACPI S3, UEFI variable services, ...).
>>>
>>> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
>>> Cc: Gerd Hoffmann <kraxel@redhat.com>
>>> Cc: Jordan Justen <jordan.l.justen@intel.com>
>>>
>>> Thanks
>>> Laszlo
>>>
>>> Laszlo Ersek (4):
>>>   OvmfPkg/PlatformPei: assign PciSize on both i440fx/q35 branches
>>>     explicitly
>>>   OvmfPkg/PlatformPei: hoist PciBase assignment above the i440fx/q35
>>>     branching
>>>   OvmfPkg/PlatformPei: reorder the 32-bit PCI hole vs. the PCIEXBAR on
>>>     q35
>>>   OvmfPkg/PlatformPei: fix MTRR for low-RAM sizes that have many bits
>>>     clear
>>>
>>>  OvmfPkg/OvmfPkgIa32.dsc         |  5 +----
>>>  OvmfPkg/OvmfPkgIa32X64.dsc      |  5 +----
>>>  OvmfPkg/OvmfPkgX64.dsc          |  5 +----
>>>  OvmfPkg/PlatformPei/MemDetect.c | 23 +++++++++++++++++---
>>>  OvmfPkg/PlatformPei/Platform.c  | 14 +++++-------
>>>  OvmfPkg/PlatformPei/Platform.h  |  2 ++
>>>  6 files changed, 31 insertions(+), 23 deletions(-)
>>>
>>