On August 25, 2022 3:42 PM, Gerd Hoffmann wrote: > Hi, > > > > Runtime service call are restricted so that you don't have > > > concurrent threads executing (see section 8.1 of the specification). > > > Without that you would have problems with runtime services today. > > > > > One of the situation of CcProbe used is in BaseIoLib. > > https://github.com/tianocore/edk2/blob/master/MdePkg/Library/BaseIoLib > > Intrinsic/IoLibInternalTdx.c#L35-L40 > > > > BaseIoLib is a basic library and it may be called by APs. While dynamic PCD > access is not allowed in APs. Of course we can cache the PCD in a variable but > I think it is still not safe. > > > > Reserving the OVMF work area as RT_DATA breaks the original intention of > the design. > > > > Then how about this solution? > > https://edk2.groups.io/g/devel/message/91132 > > We can design 2 instances of CcProbe. One is to read the OvmfWorkArea. > The other is to call Cc guest specific way to determine the type. > > When using RT_DATA is out of question there is no way around two instances > I think. > > I don't see the point in reinventing the wheel though. We know what the > guest type is, why determine it *again*? We only need to copy the guest type > from the work area to another place before it is gone. I think the dxe > library > instance could copy it to a variable in the init function. > As I mentioned CcProbe is used in BaseIoLib which is a basic library and it is used in SEC/PEI/DXE phases. Global variable cannot be used in SEC phase. Unless BaseIoLib is split into 2 instance, one for SEC/PEI phase, the other for DXE phase. Gerd, do you mean this solution?
Or there is another solution based on https://edk2.groups.io/g/devel/message/91132 We can design 2 instances of CcProbe. One is to read the OvmfWorkArea. This is for SEC/PEI phase. The other is to save the guest type in Ovmf work area to a global variable in its init function. This is for DXE phase. Thanks Min -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#92799): https://edk2.groups.io/g/devel/message/92799 Mute This Topic: https://groups.io/mt/93173995/21656 Group Owner: devel+ow...@edk2.groups.io Unsubscribe: https://edk2.groups.io/g/devel/unsub [arch...@mail-archive.com] -=-=-=-=-=-=-=-=-=-=-=-
