Laszlo: >-----Original Message----- >From: Laszlo Ersek [mailto:ler...@redhat.com] >Sent: Saturday, August 17, 2019 2:54 AM >To: Gao, Liming <liming....@intel.com>; devel@edk2.groups.io; Kinney, >Michael D <michael.d.kin...@intel.com> >Cc: Mike Turner <mike...@microsoft.com>; Wang, Jian J ><jian.j.w...@intel.com>; Wu, Hao A <hao.a...@intel.com>; Bi, Dandan ><dandan...@intel.com> >Subject: Re: [edk2-devel] [Patch] MdeModulePkg DxeCore: Fix for missing >MAT update > >On 08/16/19 17:24, Gao, Liming wrote: >> Laszlo: >> >>> -----Original Message----- >>> From: devel@edk2.groups.io [mailto:devel@edk2.groups.io] On Behalf Of >>> Laszlo Ersek >>> Sent: Friday, August 16, 2019 11:18 PM >>> To: Gao, Liming <liming....@intel.com>; devel@edk2.groups.io; Kinney, >>> Michael D <michael.d.kin...@intel.com> >>> Cc: Mike Turner <mike...@microsoft.com>; Wang, Jian J >>> <jian.j.w...@intel.com>; Wu, Hao A <hao.a...@intel.com>; Bi, Dandan >>> <dandan...@intel.com> >>> Subject: Re: [edk2-devel] [Patch] MdeModulePkg DxeCore: Fix for >>> missing MAT update >>> >>> On 08/14/19 17:55, Gao, Liming wrote: >>> >>>> If Platform PEIM doesn't build HOB, DxeIpl will not build HOB, >>> >>> My reading of the code is the opposite. If the platform PEIM does not >>> build the HOB, then the DXE IPL PEIM will attempt to build the HOB, >>> from the UEFI variable. >>> >>> At commit caa7d3a896f6, in file >>> "MdeModulePkg/Core/DxeIplPeim/DxeLoad.c", function DxeLoadCore(), >we >>> have: >>> >>> 363 if (GetFirstGuidHob ((CONST EFI_GUID >*)&gEfiMemoryTypeInformationGuid) == NULL) { >>> 364 // >>> 365 // Don't build GuidHob if GuidHob has been installed. >>> 366 // >>> 367 Status = PeiServicesLocatePpi ( >>> 368 &gEfiPeiReadOnlyVariable2PpiGuid, >>> 369 0, >>> 370 NULL, >>> 371 (VOID **)&Variable >>> 372 ); >>> 373 if (!EFI_ERROR (Status)) { >>> 374 DataSize = sizeof (MemoryData); >>> 375 Status = Variable->GetVariable ( >>> 376 Variable, >>> 377 >>> EFI_MEMORY_TYPE_INFORMATION_VARIABLE_NAME, >>> 378 &gEfiMemoryTypeInformationGuid, >>> 379 NULL, >>> 380 &DataSize, >>> 381 &MemoryData >>> 382 ); >>> 383 if (!EFI_ERROR (Status) && >ValidateMemoryTypeInfoVariable(MemoryData, DataSize)) { >> >> Only when this variable exists, Hob will be built. But, if no PEIM >> builds Hob, BDS will not set the variable. >> So, there is still no HOB. > >So how is a platform supposed to enable this feature? > >If PlatformPei never builds the HOB, the variable will never be created, >so the DXE IPL PEIM will also not build the HOB, ever. > >If PlatformPei builds the HOB with static data, then BDS will set >(update) the variable, yes, but the DXE IPL PEIM will ignore the >variable, because PlatformPei already built the HOB. > >So... Is PlatformPei supposed to use the Variable PPI, check if the >variable exists, and create the static HOB only if the variable is >absent? > >... Ugh, wait. I've actually implemented this for OVMF almost 2 years >ago! And the answer to my question is "yes": > > https://bugzilla.tianocore.org/show_bug.cgi?id=386 > https://lists.01.org/pipermail/edk2-devel/2017-November/018312.html > >See the OnReadOnlyVariable2Available() function: > >+ // >+ // Check if the "MemoryTypeInformation" variable exists, in the >+ // gEfiMemoryTypeInformationGuid namespace. >+ // >+ ReadOnlyVariable2 = Ppi; >+ DataSize = 0; >+ Status = ReadOnlyVariable2->GetVariable ( >+ ReadOnlyVariable2, >+ EFI_MEMORY_TYPE_INFORMATION_VARIABLE_NAME, >+ &gEfiMemoryTypeInformationGuid, >+ NULL, >+ &DataSize, >+ NULL >+ ); >+ if (Status == EFI_BUFFER_TOO_SMALL) { >+ // >+ // The variable exists; the DXE IPL PEIM will build the HOB from it. >+ // >+ return EFI_SUCCESS; >+ } >+ // >+ // Install the default memory type information HOB. >+ // >+ BuildMemTypeInfoHob (); > >Apologies for forgetting about this; you are right. > >Too bad my work for TianoCore#386 was rejected. :( >
So, this is one value to add PEI variable support in OVMF. Do you consider to approve this feature request? Thanks Liming >Thanks >Laszlo -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#46016): https://edk2.groups.io/g/devel/message/46016 Mute This Topic: https://groups.io/mt/32821535/21656 Group Owner: devel+ow...@edk2.groups.io Unsubscribe: https://edk2.groups.io/g/devel/unsub [arch...@mail-archive.com] -=-=-=-=-=-=-=-=-=-=-=-
