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>
# This PCD is used to set the base address of the PCI express hierarchy. It\r
# is only consulted when OVMF runs on Q35. In that case it is programmed into\r
# the PCIEXBAR register.\r
- gEfiMdePkgTokenSpaceGuid.PcdPciExpressBaseAddress|0xE0000000\r
+ #\r
+ # On Q35 machine types that QEMU intends to support in the long term, QEMU\r
+ # never lets the RAM below 4 GB exceed 2 GB.\r
+ gEfiMdePkgTokenSpaceGuid.PcdPciExpressBaseAddress|0x80000000\r
\r
!ifdef $(SOURCE_DEBUG_ENABLE)\r
gEfiSourceLevelDebugPkgTokenSpaceGuid.PcdDebugLoadImageMethod|0x2\r
# This PCD is used to set the base address of the PCI express hierarchy. It\r
# is only consulted when OVMF runs on Q35. In that case it is programmed into\r
# the PCIEXBAR register.\r
- gEfiMdePkgTokenSpaceGuid.PcdPciExpressBaseAddress|0xE0000000\r
+ #\r
+ # On Q35 machine types that QEMU intends to support in the long term, QEMU\r
+ # never lets the RAM below 4 GB exceed 2 GB.\r
+ gEfiMdePkgTokenSpaceGuid.PcdPciExpressBaseAddress|0x80000000\r
\r
!ifdef $(SOURCE_DEBUG_ENABLE)\r
gEfiSourceLevelDebugPkgTokenSpaceGuid.PcdDebugLoadImageMethod|0x2\r
# This PCD is used to set the base address of the PCI express hierarchy. It\r
# is only consulted when OVMF runs on Q35. In that case it is programmed into\r
# the PCIEXBAR register.\r
- gEfiMdePkgTokenSpaceGuid.PcdPciExpressBaseAddress|0xE0000000\r
+ #\r
+ # On Q35 machine types that QEMU intends to support in the long term, QEMU\r
+ # never lets the RAM below 4 GB exceed 2 GB.\r
+ gEfiMdePkgTokenSpaceGuid.PcdPciExpressBaseAddress|0x80000000\r
\r
!ifdef $(SOURCE_DEBUG_ENABLE)\r
gEfiSourceLevelDebugPkgTokenSpaceGuid.PcdDebugLoadImageMethod|0x2\r
PciBase = (TopOfLowRam < BASE_2GB) ? BASE_2GB : TopOfLowRam;\r
if (mHostBridgeDevId == INTEL_Q35_MCH_DEVICE_ID) {\r
//\r
- // The 32-bit PCI host aperture is expected to fall between the top of\r
- // low RAM and the base of the MMCONFIG area.\r
+ // The MMCONFIG area is expected to fall between the top of low RAM and\r
+ // the base of the 32-bit PCI host aperture.\r
//\r
PciExBarBase = FixedPcdGet64 (PcdPciExpressBaseAddress);\r
- ASSERT (PciBase < PciExBarBase);\r
+ ASSERT (TopOfLowRam <= PciExBarBase);\r
ASSERT (PciExBarBase <= MAX_UINT32 - SIZE_256MB);\r
- PciSize = (UINT32)(PciExBarBase - PciBase);\r
+ PciBase = (UINT32)(PciExBarBase + SIZE_256MB);\r
+ PciSize = 0xFC000000 - PciBase;\r
} else {\r
PciSize = 0xFC000000 - PciBase;\r
}\r