Platforms that optionally provide an IOMMU protocol should do so by including a DXE driver (usually called IoMmuDxe) that produces either the IOMMU protocol -- if the underlying capabilities are available --, or gIoMmuAbsentProtocolGuid, to signal that the IOMMU capability detection completed with negative result (i.e., no IOMMU will be available in the system).
In turn, DXE drivers (and library instances) that are supposed to use the IOMMU protocol if it is available should add the following to their DEPEX: gEdkiiIoMmuProtocolGuid OR gIoMmuAbsentProtocolGuid This ensures these client modules will only be dispatched after IOMMU detection completes (with positive or negative result). Cc: Jordan Justen <[email protected]> Cc: Laszlo Ersek <[email protected]> Cc: Leo Duran <[email protected]> Contributed-under: TianoCore Contribution Agreement 1.0 Suggested-by: Jordan Justen <[email protected]> Suggested-by: Laszlo Ersek <[email protected]> Signed-off-by: Brijesh Singh <[email protected]> Reviewed-by: Laszlo Ersek <[email protected]> --- OvmfPkg/OvmfPkg.dec | 1 + 1 file changed, 1 insertion(+) diff --git a/OvmfPkg/OvmfPkg.dec b/OvmfPkg/OvmfPkg.dec index e5f74a1248ed..27bcfc141e5a 100644 --- a/OvmfPkg/OvmfPkg.dec +++ b/OvmfPkg/OvmfPkg.dec @@ -69,6 +69,7 @@ [Protocols] gBlockMmioProtocolGuid = {0x6b558ce3, 0x69e5, 0x4c67, {0xa6, 0x34, 0xf7, 0xfe, 0x72, 0xad, 0xbe, 0x84}} gXenBusProtocolGuid = {0x3d3ca290, 0xb9a5, 0x11e3, {0xb7, 0x5d, 0xb8, 0xac, 0x6f, 0x7d, 0x65, 0xe6}} gXenIoProtocolGuid = {0x6efac84f, 0x0ab0, 0x4747, {0x81, 0xbe, 0x85, 0x55, 0x62, 0x59, 0x04, 0x49}} + gIoMmuAbsentProtocolGuid = {0xf8775d50, 0x8abd, 0x4adf, {0x92, 0xac, 0x85, 0x3e, 0x51, 0xf6, 0xc8, 0xdc}} [PcdsFixedAtBuild] gUefiOvmfPkgTokenSpaceGuid.PcdOvmfPeiMemFvBase|0x0|UINT32|0 -- 2.7.4 _______________________________________________ edk2-devel mailing list [email protected] https://lists.01.org/mailman/listinfo/edk2-devel
