On Tue, 9 Mar 2021 at 19:10, Rob Clark <robdclark@xxxxxxxxx> wrote: > > On Mon, Mar 8, 2021 at 7:22 PM Shawn Guo <shawn.guo@xxxxxxxxxx> wrote: > > > > 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. > > fwiw, the valid use-case for ACPI boot on these things is for distro > installer.. it might not be the shiny accelerated experience, but you > want to be able to get thru the installer and then install updates to > get latest kernel/dtb/etc > > it is a small use-case, but kinda an important step ;-) > That is a fair point. However, as I understand it, we need this to work around - the need to pass efi=novamap - broken poweroff on Flex5g So an installer either needs to set the EFI variable, or pass efi=novamap on the first boot. Note that there are no arm64 EFI systems known where efi=novamap causes problems. In fact, I would prefer to stop using SetVirtualAddressMap() altogether, as it does not provide any benefit whatsoever. So perhaps we should make efi=novamap the default and be done with it. Broken poweroff is hardly a showstopper for an installer, given that we cannot even install GRUB correctly. In summary, I am more than happy to collaborate constructively on this (which is why I wrote the patch), but I don't think we're at a point yet where this is the only thing standing in our way when it comes to a smooth out-of-the-box Linux installation experience.
