On Mon, 15 Jan 2024 at 14:07, Nhi Pham <n...@os.amperecomputing.com> wrote: > > On 1/12/2024 4:45 PM, Laszlo Ersek wrote: > > (Independently: I think that's a valid thing to do for *SMM* drivers, > > because the entry point functions of those drivers are permitted to use > > both SMM and DXE/UEFI protocols. But whether the same is valid for the > > *standalone* MM drivers -- that looks questionable. Standalone MM > > drivers should not depend on UEFI/DXE protocols ever, IIUC.) > > > >> 3) The issue is patching the grammar in place, why can’t we just make a > >> copy for the dispatcher grammer, and operate on the copy. Maybe via a > >> copy on 1st update strategy? > > > > Yes, copying the depex to the heap, and patching it there, was Nhi's #1 > > fix proposal. I think that could be made work. But I'm not sure if the > > perf savings are worth the additional complexity. The heap allocation > > (where the writeable depex would exist) would have to be permanently > > associated with the loaded PE image -- because the dispatcher might need > > to reevaluate the depex across multiple rounds of dispatching. So that's > > a new field in some image-related structure, it also needs to be freed > > upon unload (?), what if the memory allocation fails during depex eval > > (just consider the depex to eval to FALSE?), etc. Doable, but hairy; not > > sure if the perf is worth that effort. > > > > Thanks so much, Laszlo for your valuable insights. > > The approach #1 works for me. I will do further check for your concerns > above. > > I'm trying your suggested patch and investigating the performance being > discussed here. >
Not sure what approach #1 means, but I'd prefer to just remove this optimization from standalone MM, given that not only a) it shouldn't have to deal with a large number of protocol GUIDs, but also b) the driver dispatch is much more straight-forward. (Typically, StMM drivers can be dispatched in the order they appear in the firmware volume, in which case each DEPEX is evaluated only once anyway) -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#113822): https://edk2.groups.io/g/devel/message/113822 Mute This Topic: https://groups.io/mt/103594587/21656 Group Owner: devel+ow...@edk2.groups.io Unsubscribe: https://edk2.groups.io/g/devel/unsub [arch...@mail-archive.com] -=-=-=-=-=-=-=-=-=-=-=-
