On Mon, Mar 08, 2021 at 02:34:48PM +0100, Ard Biesheuvel wrote: > On Sun, 7 Mar 2021 at 12:02, Shawn Guo <shawn.guo@xxxxxxxxxx> wrote: > > > > On Sat, Mar 06, 2021 at 12:35:19PM +0100, Ard Biesheuvel wrote: > > > Allow EFI systems to override the set of supported runtime services > > > declared via the RT_PROP table, by checking for the existence of a > > > 'OverrideSupported' EFI variable of the appropriate size under the > > > RT_PROP table GUID, and if it does, combine the supported mask using > > > logical AND. (This means the override can only remove support, not > > > add it back). > > > > > > Cc: Jeffrey Hugo <jhugo@xxxxxxxxxxxxxx>, > > > Cc: Bjorn Andersson <bjorn.andersson@xxxxxxxxxx> > > > Cc: Shawn Guo <shawn.guo@xxxxxxxxxx> > > > Cc: Rob Clark <robdclark@xxxxxxxxx> > > > Cc: Leif Lindholm <leif@xxxxxxxxxxxx> > > > Cc: linux-arm-msm@xxxxxxxxxxxxxxx > > > > > > Signed-off-by: Ard Biesheuvel <ardb@xxxxxxxxxx> > > > > Awesome, Ard! On both Lenovo Yoga C630 and Flex 5G latops: > > > > Tested-by: Shawn Guo <shawn.guo@xxxxxxxxxx> > > > > With 'OverrideSupported' EFI variable added from UEFI Shell, we can drop > > 'efi=novamap' kernel cmdline and get around the broken poweroff runtime > > services nicely. Thanks! > > > > Thanks for confirming. > > However, I am not going to merge this without some justification, and > hopefully some input from other folks (Leif?) > > RTPROP already provides what we need on all platforms that use > DtbLoader, and the patch for that is queued up for v5.12-rcX, with a > cc:stable to v5.10. This allows any RT service to be marked as > disabled, including SetVirtualAddressMap(). > > So afaict, that means that this patch would be a special case for > Flex5G, right? It's for all Snapdragon based laptops, as we need to disable SetVirtualAddressMap runtime services on all of them. > So how are platforms such as this one going to load the > DTB? If some loader will be involved (or even just GRUB), Yes, GRUB. > shouldn't it > be that component that sets RTPROP like DtbLoader will, not the kernel > itself. > > Btw I don't think ACPI boot is a use case here. I don't see a software > framebuffer with no wifi support as a usage mode that justifies > carrying EFI stub hacks for everyone. Okay. I'm fine to carry it as an out-of-tree patch until someday you consider ACPI boot is useful for everyone. But I do boot these laptops with ACPI at daily basis right now as arm64 native build machine, with USB Ethernet adapter. Shawn
