diff options
| author | Laszlo Ersek <lersek@redhat.com> | 2019-05-29 11:51:26 +0200 |
|---|---|---|
| committer | Laszlo Ersek <lersek@redhat.com> | 2019-06-03 19:54:01 +0200 |
| commit | eb4d62b0779c3a5766174e4373c95a8b6a967cb7 (patch) | |
| tree | 6738d11ea384c8574b4b475c8eb83e538a4f47e6 /OvmfPkg/OvmfPkgX64.dsc | |
| parent | 305cd4f783fe522230677677d17ae7adc85ebc4b (diff) | |
Revert "OvmfPkg/PlatformPei: reorder the 32-bit PCI window vs. the PCIEXBAR on q35"
This reverts commit 75136b29541b0e093a51d2e2c2af8d19855c2b60.
The original fix for <https://bugzilla.tianocore.org/show_bug.cgi?id=1814>
triggered a bug / incorrect assumption in QEMU.
QEMU assumes that the PCIEXBAR is below the 32-bit PCI window, not above
it. When the firmware doesn't satisfy this assumption, QEMU generates an
\_SB.PCI0._CRS object in the ACPI DSDT that does not reflect the
firmware's 32-bit MMIO BAR assignments. This causes OSes to re-assign
32-bit MMIO BARs.
Working around the problem in the firmware looks less problematic than
fixing QEMU. Revert the original changes first, before implementing an
alternative fix.
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=1859
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Philippe Mathieu-Daude <philmd@redhat.com>
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Diffstat (limited to 'OvmfPkg/OvmfPkgX64.dsc')
| -rw-r--r-- | OvmfPkg/OvmfPkgX64.dsc | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/OvmfPkg/OvmfPkgX64.dsc b/OvmfPkg/OvmfPkgX64.dsc index 56a9560262..733a4c9d8a 100644 --- a/OvmfPkg/OvmfPkgX64.dsc +++ b/OvmfPkg/OvmfPkgX64.dsc @@ -495,7 +495,10 @@ # This PCD is used to set the base address of the PCI express hierarchy. It
# is only consulted when OVMF runs on Q35. In that case it is programmed into
# the PCIEXBAR register.
- gEfiMdePkgTokenSpaceGuid.PcdPciExpressBaseAddress|0xE0000000
+ #
+ # On Q35 machine types that QEMU intends to support in the long term, QEMU
+ # never lets the RAM below 4 GB exceed 2 GB.
+ gEfiMdePkgTokenSpaceGuid.PcdPciExpressBaseAddress|0x80000000
!ifdef $(SOURCE_DEBUG_ENABLE)
gEfiSourceLevelDebugPkgTokenSpaceGuid.PcdDebugLoadImageMethod|0x2
|