[edk2-devel] [PATCH for-edk2-stable201905 0/6] work around a QEMU issue triggered by the original TianoCore#1814 fix

[Laszlo Ersek]

Bugzilla: https://bugzilla.tianocore.org/show_bug.cgi?id=1859
Repo:     https://github.com/lersek/edk2.git
Branch:   exbar_mtrr_bz_1859

The fix (commit range 3b7a897cd8e3..39b9a5ffe661) for
<https://bugzilla.tianocore.org/show_bug.cgi?id=1814> is technically
correct, but it tickles an (arguably unjustified) assumption in QEMU the
wrong way. For end users, this makes the original fix for TianoCore#1814
a regression, under certain circumstances.

In theory, the assumption should be eliminated in QEMU, but in practice,
that could be quite intrusive and/or take long. It seems possible to
work around the problem in OVMF, satisfying the assumption again; for
that, OVMF needs a different fix (and a different trade-off) for the
original problem described in TianoCore#1814.

Please see the detailed problem statement and the workaround's idea in
TianoCore#1859.

If possible, I'd like to get this into edk2-stable201905 (which we're
postponing by two weeks anyway, for the sake of the OpenSSL 1.1.1b
upgrade).

Cc: Ard Biesheuvel <ard.biesheuvel at linaro.org>
Cc: Gerd Hoffmann <kraxel at redhat.com>
Cc: Jordan Justen <jordan.l.justen at intel.com>

Thanks,
Laszlo

Laszlo Ersek (6):
  Revert "OvmfPkg/PlatformPei: fix MTRR for low-RAM sizes that have many
    bits clear"
  Revert "OvmfPkg/PlatformPei: reorder the 32-bit PCI window vs. the
    PCIEXBAR on q35"
  Revert "OvmfPkg/PlatformPei: hoist PciBase assignment above the
    i440fx/q35 branching"
  Revert "OvmfPkg/PlatformPei: assign PciSize on both i440fx/q35
    branches explicitly"
  OvmfPkg: raise the PCIEXBAR base to 2816 MB on Q35
  OvmfPkg/PlatformPei: set 32-bit UC area at PciBase / PciExBarBase
    (pc/q35)

 OvmfPkg/OvmfPkgIa32.dsc         |  5 +-
 OvmfPkg/OvmfPkgIa32X64.dsc      |  5 +-
 OvmfPkg/OvmfPkgX64.dsc          |  5 +-
 OvmfPkg/PlatformPei/Platform.h  |  5 ++
 OvmfPkg/PlatformPei/MemDetect.c | 70 +++++++++++++++-----
 OvmfPkg/PlatformPei/Platform.c  | 17 +++--
 6 files changed, 80 insertions(+), 27 deletions(-)

-- 
2.19.1.3.g30247aa5d201


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