Hi David and Laszlo,
(with broken threading because gmane still mirrors the old ML ...)
Mostly, this is only necessary for devices that the CSM might have
native support for, such as VirtIO and NVMe; PciBusDxe will already
degrade devices to 32-bit if they have an OpROM.
However, there doesn't seem to be a generic way of requesting PciBusDxe
to downgrade specific devices.
There's IncompatiblePciDeviceSupportProtocol but that doesn't provide
the PCI class information or a handle to the device itself, so there's
no simple way to just match on all NVMe devices, for example.
Just leave gUefiOvmfPkgTokenSpaceGuid.PcdPciMmio64Size set to zero for
CSM builds, until/unless that can be fixed.
Signed-off-by: David Woodhouse <dwmw2@...>
Reviewed-by: Laszlo Ersek <lersek@...>
---
OvmfPkg/OvmfPkgIa32X64.dsc | 4 ++++
OvmfPkg/OvmfPkgX64.dsc | 4 ++++
2 files changed, 8 insertions(+)
diff --git a/OvmfPkg/OvmfPkgIa32X64.dsc b/OvmfPkg/OvmfPkgIa32X64.dsc
index 639e33cb285f..ad20531ceb8b 100644
--- a/OvmfPkg/OvmfPkgIa32X64.dsc
+++ b/OvmfPkg/OvmfPkgIa32X64.dsc
@@ -543,7 +543,11 @@ [PcdsDynamicDefault]
gUefiOvmfPkgTokenSpaceGuid.PcdPciMmio32Base|0x0
gUefiOvmfPkgTokenSpaceGuid.PcdPciMmio32Size|0x0
gUefiOvmfPkgTokenSpaceGuid.PcdPciMmio64Base|0x0
+!ifdef $(CSM_ENABLE)
+ gUefiOvmfPkgTokenSpaceGuid.PcdPciMmio64Size|0x0
+!else
gUefiOvmfPkgTokenSpaceGuid.PcdPciMmio64Size|0x800000000
+!endif
gEfiMdePkgTokenSpaceGuid.PcdPlatformBootTimeOut|0
diff --git a/OvmfPkg/OvmfPkgX64.dsc b/OvmfPkg/OvmfPkgX64.dsc
index 69a3497c2c9e..0542ac2235b4 100644
--- a/OvmfPkg/OvmfPkgX64.dsc
+++ b/OvmfPkg/OvmfPkgX64.dsc
@@ -542,7 +542,11 @@ [PcdsDynamicDefault]
gUefiOvmfPkgTokenSpaceGuid.PcdPciMmio32Base|0x0
gUefiOvmfPkgTokenSpaceGuid.PcdPciMmio32Size|0x0
gUefiOvmfPkgTokenSpaceGuid.PcdPciMmio64Base|0x0
+!ifdef $(CSM_ENABLE)
+ gUefiOvmfPkgTokenSpaceGuid.PcdPciMmio64Size|0x0
IIRC x86 Linux just takes firmware provided BAR maps as they are and
doesn't map on its own. Or does it map if a BAR was previously unmapped?
In the former case, wouldn't that mean that we're breaking GPU
passthrough (*big* BARs) for OVMF if the OVMF version happens to support
CSM? So if a distro decides to turn on CSM, that would be a very subtle
regression.
Would it be possible to change the PCI mapping logic to just simply
*prefer* low BAR space if there's some available and the BAR is not big
(<64MB for example)?
That way we could have CSM enabled OVMF for everyone ;)
Alex
+!else
gUefiOvmfPkgTokenSpaceGuid.PcdPciMmio64Size|0x800000000
+!endif
gEfiMdePkgTokenSpaceGuid.PcdPlatformBootTimeOut|0
--
2.21.0
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