Hi, > > > + ## This dynamic PCD indicates whether CPU MMU is enabled. > > > + # TRUE - CPU MMU is enabled. > > > + # FASLE - CPU MMU have not enabled. > > > + gUefiCpuPkgTokenSpaceGuid.PcdCpuMmuIsEnabled|FALSE|BOOLEAN|0x60000023 > > Why create a PCD for this? Can't you simply read the control register > > to figure whenever paging is enabled or not?
> This is a good question. When I designed the API of > SetMemoryRegionAttributes, it only contained 4 parameters, namely Start, > Size, Attribut and Mask(refer to ARM version), and the MmuInitLib needs call > this API to configure or initialize the MMU. SetMemoryRegionAttributes will > call a private function called UpdateRegionMapping, it needs to know if the > MMU is started to do different logic(such as wether should be invalidated > TLB when filling the tables for the first time, etc), therefore, there > create a new PCD to let it know this. BTW, ARM and RISC-V have the same > logic. Yes, UpdateRegionMapping needs to know this, no doubt. But do we need a PCD for this? Looks like a pointless indirection to me. Arm has a ArmMmuEnabled() functions which goes read the control registers directly. take care, Gerd -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#116801): https://edk2.groups.io/g/devel/message/116801 Mute This Topic: https://groups.io/mt/104859880/21656 Group Owner: devel+ow...@edk2.groups.io Unsubscribe: https://edk2.groups.io/g/devel/unsub [arch...@mail-archive.com] -=-=-=-=-=-=-=-=-=-=-=-
