Hi Gerd, The following library provides an example of all the steps to register an MMIO range for RT access.
https://github.com/tianocore/edk2/blob/master/MdePkg/Library/DxeRuntimePciExpressLib/PciExpressLib.c The example is from PCI Express, but the PCI Config space for PCI Express is an MMIO window. This library contains a Constructor/Destructor to create/close a Set Virtual Address Map event. It has the Set Virtual Address Map Event Notification Function and a function to request a specific 4KB portion of the 256 MB MMIO window to be marked as RT. DxeRuntimePciExpressLibConstructor() DxeRuntimePciExpressLibDestructor() DxeRuntimePciExpressLibVirtualNotify() PciExpressRegisterForRuntimeAccess() Best regards, Mike > -----Original Message----- > From: devel@edk2.groups.io <devel@edk2.groups.io> On Behalf Of Yao, Jiewen > Sent: Monday, August 30, 2021 6:02 AM > To: devel@edk2.groups.io; kra...@redhat.com > Subject: Re: [edk2-devel] mmio mappings for runtime service > > The BIOS driver must set EFI_RUNTIME_MEMORY attribute for the > EfiGcdMemoryTypeMemoryMappedIo region with GCD service gDS- > >SetMemorySpaceAttributes(). > Then DXE will report EfiMemoryMappedIO with EFI_RUNTIME_MEMORY attribute in > UEFI memory map. > The OS will gBS->GetMemoryMap() and assign virtual address for the MMIO, and > gRT->SetVirtualAddressMap() back to the BIOS. > > Finally, the BIOS driver can gRT->ConvertPointer() the MMIO physical address > to virtual address, then access it at > runtime. > > Thank you > Yao Jiewen > > > -----Original Message----- > > From: devel@edk2.groups.io <devel@edk2.groups.io> On Behalf Of Gerd > > Hoffmann > > Sent: Monday, August 30, 2021 6:24 PM > > To: devel@edk2.groups.io > > Subject: [edk2-devel] mmio mappings for runtime service > > > > Hi, > > > > What is the correct way to make sure runtime services can access > > mmio registers, i.e. that there is a mapping in the page tables > > for the mmio page needed? > > > > Is that the job of the firmware? > > Or should the OS calling the runtime service handle that? > > In case of the latter: How does the OS figure which pages are needed? > > > > thanks, > > Gerd > > > > > > > > > > > > > > > -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#79956): https://edk2.groups.io/g/devel/message/79956 Mute This Topic: https://groups.io/mt/85247585/21656 Group Owner: devel+ow...@edk2.groups.io Unsubscribe: https://edk2.groups.io/g/devel/unsub [arch...@mail-archive.com] -=-=-=-=-=-=-=-=-=-=-=-
