It's a UINT8 (enum) PCD telling where the PcdVideoHorizontalResolution
and PcdVideoVerticalResolution values are coming from. It can be:
0 (unset aka default from dsc file), or
1 (from PlatformConfig), or
2 (set by Video Driver).
It will be used by video drivers to avoid overriding PlatformConfig
values, or override each others values in case multiple display devices
are present.
The underlying problem this tries to solve is that the GOP protocol has
no way to indicate the preferred video mode. On physical hardware this
isn't much of a problem because using the highest resolution available
works just fine as that is typically the native display resolution
But in a virtual machine you don't want come up with a huge 4k window by
default just because the virtual vga is able to handle that. Cutting
down the video mode list isn't a great solution either as that would
also remove the modes from the platform configuration so the user
wouldn't be able to pick a resolution higher than the default any more.
So with patch drivers can use use PcdVideoHorizontalResolution and
PcdVideoVerticalResolution to indicate what the preferred display
resolution is, without overwriting the user preferences from
PlatformConfig if present.
A possible alternative approach would be to extend the GOP protocol, but
I'm not sure this is a good plan given this is mostly a problem for
virtual machines and using PCDs allows to keep this local to OvmfPkg.
Signed-off-by: Gerd Hoffmann <kra...@redhat.com>
---
OvmfPkg/OvmfPkg.dec | 7 +++++++
OvmfPkg/AmdSev/AmdSevX64.dsc | 1 +
OvmfPkg/Microvm/MicrovmX64.dsc | 1 +
OvmfPkg/OvmfPkgIa32.dsc | 1 +
OvmfPkg/OvmfPkgIa32X64.dsc | 1 +
OvmfPkg/OvmfPkgX64.dsc | 1 +
OvmfPkg/OvmfXen.dsc | 1 +
OvmfPkg/PlatformDxe/Platform.inf | 1 +
OvmfPkg/PlatformDxe/Platform.c | 3 +++
9 files changed, 17 insertions(+)
diff --git a/OvmfPkg/OvmfPkg.dec b/OvmfPkg/OvmfPkg.dec
index 769bef0ffa12..7aa94ca02863 100644
--- a/OvmfPkg/OvmfPkg.dec
+++ b/OvmfPkg/OvmfPkg.dec
@@ -408,6 +408,13 @@ [PcdsDynamic, PcdsDynamicEx]
# instance in PiSmmCpuDxeSmm, and CpuHotplugSmm.
gUefiOvmfPkgTokenSpaceGuid.PcdCpuHotEjectDataAddress|0|UINT64|0x46
+ ## This PCD tracks where PcdVideo{Horizontal,Vertical}Resolution
+ # values are coming from.
+ # 0 - unset (defaults from platform dsc)
+ # 1 - set from PlatformConfig
+ # 2 - set by GOP Driver.
+ gUefiOvmfPkgTokenSpaceGuid.PcdVideoResolutionSource|0|UINT8|0x64
+
[PcdsFeatureFlag]
gUefiOvmfPkgTokenSpaceGuid.PcdQemuBootOrderPciTranslation|TRUE|BOOLEAN|0x1c
gUefiOvmfPkgTokenSpaceGuid.PcdQemuBootOrderMmioTranslation|FALSE|BOOLEAN|0x1d
diff --git a/OvmfPkg/AmdSev/AmdSevX64.dsc b/OvmfPkg/AmdSev/AmdSevX64.dsc
index 04ae61cf69d8..343ac643f021 100644
--- a/OvmfPkg/AmdSev/AmdSevX64.dsc
+++ b/OvmfPkg/AmdSev/AmdSevX64.dsc
@@ -527,6 +527,7 @@ [PcdsDynamicDefault]
gEfiMdeModulePkgTokenSpaceGuid.PcdVideoHorizontalResolution|800
gEfiMdeModulePkgTokenSpaceGuid.PcdVideoVerticalResolution|600
gEfiMdeModulePkgTokenSpaceGuid.PcdAcpiS3Enable|FALSE
+ gUefiOvmfPkgTokenSpaceGuid.PcdVideoResolutionSource|0
gUefiOvmfPkgTokenSpaceGuid.PcdOvmfHostBridgePciDevId|0
gUefiOvmfPkgTokenSpaceGuid.PcdPciIoBase|0x0
gUefiOvmfPkgTokenSpaceGuid.PcdPciIoSize|0x0
diff --git a/OvmfPkg/Microvm/MicrovmX64.dsc b/OvmfPkg/Microvm/MicrovmX64.dsc
index 1c2e600febee..cb28bd8bba2c 100644
--- a/OvmfPkg/Microvm/MicrovmX64.dsc
+++ b/OvmfPkg/Microvm/MicrovmX64.dsc
@@ -560,6 +560,7 @@ [PcdsDynamicDefault]
gEfiMdeModulePkgTokenSpaceGuid.PcdVideoHorizontalResolution|800
gEfiMdeModulePkgTokenSpaceGuid.PcdVideoVerticalResolution|600
gEfiMdeModulePkgTokenSpaceGuid.PcdAcpiS3Enable|FALSE
+ gUefiOvmfPkgTokenSpaceGuid.PcdVideoResolutionSource|0
gUefiOvmfPkgTokenSpaceGuid.PcdOvmfHostBridgePciDevId|0
gUefiOvmfPkgTokenSpaceGuid.PcdPciIoBase|0x0
gUefiOvmfPkgTokenSpaceGuid.PcdPciIoSize|0x0
diff --git a/OvmfPkg/OvmfPkgIa32.dsc b/OvmfPkg/OvmfPkgIa32.dsc
index 085cc7ece15d..2f05d93ed4af 100644
--- a/OvmfPkg/OvmfPkgIa32.dsc
+++ b/OvmfPkg/OvmfPkgIa32.dsc
@@ -590,6 +590,7 @@ [PcdsDynamicDefault]
gEfiMdeModulePkgTokenSpaceGuid.PcdVideoHorizontalResolution|800
gEfiMdeModulePkgTokenSpaceGuid.PcdVideoVerticalResolution|600
gEfiMdeModulePkgTokenSpaceGuid.PcdAcpiS3Enable|FALSE
+ gUefiOvmfPkgTokenSpaceGuid.PcdVideoResolutionSource|0
gUefiOvmfPkgTokenSpaceGuid.PcdOvmfHostBridgePciDevId|0
gUefiOvmfPkgTokenSpaceGuid.PcdPciIoBase|0x0
gUefiOvmfPkgTokenSpaceGuid.PcdPciIoSize|0x0
diff --git a/OvmfPkg/OvmfPkgIa32X64.dsc b/OvmfPkg/OvmfPkgIa32X64.dsc
index 0ce122ddb50c..bcab54aaa02a 100644
--- a/OvmfPkg/OvmfPkgIa32X64.dsc
+++ b/OvmfPkg/OvmfPkgIa32X64.dsc
@@ -596,6 +596,7 @@ [PcdsDynamicDefault]
gEfiMdeModulePkgTokenSpaceGuid.PcdVideoHorizontalResolution|800
gEfiMdeModulePkgTokenSpaceGuid.PcdVideoVerticalResolution|600
gEfiMdeModulePkgTokenSpaceGuid.PcdAcpiS3Enable|FALSE
+ gUefiOvmfPkgTokenSpaceGuid.PcdVideoResolutionSource|0
gUefiOvmfPkgTokenSpaceGuid.PcdOvmfHostBridgePciDevId|0
gUefiOvmfPkgTokenSpaceGuid.PcdPciIoBase|0x0
gUefiOvmfPkgTokenSpaceGuid.PcdPciIoSize|0x0
diff --git a/OvmfPkg/OvmfPkgX64.dsc b/OvmfPkg/OvmfPkgX64.dsc
index 4589adff388d..ee0fdf492fd4 100644
--- a/OvmfPkg/OvmfPkgX64.dsc
+++ b/OvmfPkg/OvmfPkgX64.dsc
@@ -595,6 +595,7 @@ [PcdsDynamicDefault]
gEfiMdeModulePkgTokenSpaceGuid.PcdVideoHorizontalResolution|800
gEfiMdeModulePkgTokenSpaceGuid.PcdVideoVerticalResolution|600
gEfiMdeModulePkgTokenSpaceGuid.PcdAcpiS3Enable|FALSE
+ gUefiOvmfPkgTokenSpaceGuid.PcdVideoResolutionSource|0
gUefiOvmfPkgTokenSpaceGuid.PcdOvmfHostBridgePciDevId|0
gUefiOvmfPkgTokenSpaceGuid.PcdPciIoBase|0x0
gUefiOvmfPkgTokenSpaceGuid.PcdPciIoSize|0x0
diff --git a/OvmfPkg/OvmfXen.dsc b/OvmfPkg/OvmfXen.dsc
index de0d30bfb807..1f6352195b75 100644
--- a/OvmfPkg/OvmfXen.dsc
+++ b/OvmfPkg/OvmfXen.dsc
@@ -468,6 +468,7 @@ [PcdsDynamicDefault]
gEfiMdeModulePkgTokenSpaceGuid.PcdVideoHorizontalResolution|800
gEfiMdeModulePkgTokenSpaceGuid.PcdVideoVerticalResolution|600
gEfiMdeModulePkgTokenSpaceGuid.PcdAcpiS3Enable|FALSE
+ gUefiOvmfPkgTokenSpaceGuid.PcdVideoResolutionSource|0
gUefiOvmfPkgTokenSpaceGuid.PcdOvmfHostBridgePciDevId|0
gUefiOvmfPkgTokenSpaceGuid.PcdPciIoBase|0x0
gUefiOvmfPkgTokenSpaceGuid.PcdPciIoSize|0x0
diff --git a/OvmfPkg/PlatformDxe/Platform.inf b/OvmfPkg/PlatformDxe/Platform.inf
index 14727c1220e8..d2f75d78b601 100644
--- a/OvmfPkg/PlatformDxe/Platform.inf
+++ b/OvmfPkg/PlatformDxe/Platform.inf
@@ -47,6 +47,7 @@ [LibraryClasses]
[Pcd]
gEfiMdeModulePkgTokenSpaceGuid.PcdVideoHorizontalResolution
gEfiMdeModulePkgTokenSpaceGuid.PcdVideoVerticalResolution
+ gUefiOvmfPkgTokenSpaceGuid.PcdVideoResolutionSource
[Protocols]
gEfiDevicePathProtocolGuid ## PRODUCES
diff --git a/OvmfPkg/PlatformDxe/Platform.c b/OvmfPkg/PlatformDxe/Platform.c
index 69a7ecb83d03..4bf22712c78f 100644
--- a/OvmfPkg/PlatformDxe/Platform.c
+++ b/OvmfPkg/PlatformDxe/Platform.c
@@ -742,6 +742,9 @@ ExecutePlatformConfig (
PlatformConfig.VerticalResolution
);
ASSERT_RETURN_ERROR (PcdStatus);
+
+ PcdStatus = PcdSet8S (PcdVideoResolutionSource, 1);
+ ASSERT_RETURN_ERROR (PcdStatus);
}
return EFI_SUCCESS;
--
2.34.1
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