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

["Michael D Kinney" <michael.d.kinney@intel.com>]

Looks like a bug fix to me and is fine for soft freeze period.

To commit during hard freeze, just need to show it is a critical bug.

Mike

> -----Original Message-----
> From: Leif Lindholm [mailto:leif.lindholm@linaro.org]
> Sent: Wednesday, May 15, 2019 4:57 AM
> To: Laszlo Ersek <lersek@redhat.com>
> Cc: edk2-devel-groups-io <devel@edk2.groups.io>; Ard
> Biesheuvel <ard.biesheuvel@linaro.org>; Kinney, Michael
> D <michael.d.kinney@intel.com>; Andrew Fish
> <afish@apple.com>; Gerd Hoffmann <kraxel@redhat.com>;
> Justen, Jordan L <jordan.l.justen@intel.com>
> Subject: Re: [edk2-devel] [PATCH 0/4]
> OvmfPkg/PlatformPei: fix two assertion failures with
> weird RAM sizes
> 
> 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.
> 
> 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(-)
> > >
> >