On 5/29/19 5:12 PM, Laszlo Ersek wrote:
> This reverts commit 9a2e8d7c65ef7f39c6754d27e52954b616bc6628.
>
> 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>
> ---
> OvmfPkg/PlatformPei/Platform.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/OvmfPkg/PlatformPei/Platform.c b/OvmfPkg/PlatformPei/Platform.c
> index 9c013613a1a0..5e0a15484230 100644
> --- a/OvmfPkg/PlatformPei/Platform.c
> +++ b/OvmfPkg/PlatformPei/Platform.c
> @@ -181,7 +181,6 @@ MemMapInitialization (
>
> TopOfLowRam = GetSystemMemorySizeBelow4gb ();
> PciExBarBase = 0;
> - PciBase = (TopOfLowRam < BASE_2GB) ? BASE_2GB : TopOfLowRam;
> if (mHostBridgeDevId == INTEL_Q35_MCH_DEVICE_ID) {
> //
> // The MMCONFIG area is expected to fall between the top of low RAM and
> @@ -193,6 +192,7 @@ MemMapInitialization (
> PciBase = (UINT32)(PciExBarBase + SIZE_256MB);
> PciSize = 0xFC000000 - PciBase;
> } else {
> + PciBase = (TopOfLowRam < BASE_2GB) ? BASE_2GB : TopOfLowRam;
> PciSize = 0xFC000000 - PciBase;
> }
>
>
-=-=-=-=-=-=-=-=-=-=-=-
Groups.io Links: You receive all messages sent to this group.
View/Reply Online (#41636): https://edk2.groups.io/g/devel/message/41636
Mute This Topic: https://groups.io/mt/31834715/1787277
Group Owner: devel+owner@edk2.groups.io
Unsubscribe: https://edk2.groups.io/g/devel/unsub [importer@patchew.org]
-=-=-=-=-=-=-=-=-=-=-=-