On Wed, Oct 12, 2022 at 10:23:12AM +0200, Hans de Goede wrote: > On 10/11/22 19:40, Bjorn Helgaas wrote: > > On Mon, Oct 10, 2022 at 05:02:06PM +0200, Hans de Goede wrote: > >> Clevo NL4XLU barebones have the same E820 reservation covering > >> the entire _CRS 32-bit window issue as the Lenovo *IIL* and > >> Clevo X170KM-G models, relevant dmesg bits (with pci=no_e820): > >> ... > >> Add a no_e820 quirk for these models to fix the touchpad not working > >> (due to Linux being unable to assign a PCI BAR for the i2c-controller). > > > > I do plan to apply this, but a little food for thought below. > > > > I explored this issue a little bit with the ACPI/UEFI folks (see > > https://members.uefi.org/wg/aswg/mail/thread/9265 if you have access). > > > > One aspect I had glossed over earlier is that on most recent machines, > > the "E820 map" Linux uses is actually constructed internally by Linux > > based on the UEFI memory map, and that construction conflates several > > EFI types into E820_TYPE_RESERVED; see > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/firmware/efi/libstub/x86-stub.c?id=v5.19#n576 Critical error on my part here: the E820 map is passed to Linux by the bootloader or the EFI stub, NOT constructed by Linux. > > From a response in the ACPI/UEFI discussion: > > > > The reason EfiMemoryMappedIO[1] exist in the UEFI memory map is to > > request a virtual mapping for UEFI Runtime Services. > > ... > > Thus the EfiMemoryMappedIO entries just exist to pass up the > > EFI_MEMORY_RUNTIME attribute in the UEFI Memory Map. This is the part > > of the contract for UEFI Runtime Service to use virtual mappings > > provided by the OS. So from an OS point of view EfiMemoryMappedIO has > > no other purpose. > > > > [1] UEFI: Table 7-5 Memory Type Usage before ExitBootServices() "Used > > by system firmware to request that a memory-mapped IO region be > > mapped by the OS to a virtual address so it can be accessed by EFI > > runtime services." > > I'm a little leery of changing that UEFI->E820 conversion because of > > other possible implications, but it may be that omitting > > EfiMemoryMappedIO entries from the E820 map and keeping the original > > "avoid E820 regions" (4dc2287c1805) would also solve this problem. > > Actually during my many attempts to fix this I did write a patch > adding a new E820_TYPE_MMIO to the generated e820-memmap which > would only show up in the EFI -> E820 entry generation case > and then used that to not exclude that E820 region, see > this RFC series: > > https://lore.kernel.org/linux-pci/20220214151759.98267-1-hdegoede@xxxxxxxxxx/ Yes :) I tried something similar and of course it didn't work because it didn't change the E820 map coming from the bootloader. > I also did another series which used the EfiMemoryMappedIO type as > an input to heuristics to automatically set pci=no_e820, see: > > https://lore.kernel.org/linux-pci/20220228105259.230903-1-hdegoede@xxxxxxxxxx/ > > IIRC that patch eventually got replaced by a similar but simpler > heuristic from you. Which IIRC eventually got dropped again because > it was causing regressions on some models again. > > So we ended up with the current set pci=no_e820 using DMI based quirks + > try to enable it for all BIOS-es with date >= 2023 approach, > with the plan to do DMI quirks setting pci=use_e820 if any (buggy) > 2023 BIOS-es show up which need this. I gave up on figuring out what went wrong in this path. Anyway, I've had the patch below in -next for a couple weeks, but I plan to drop it and replace it with the series here: https://lore.kernel.org/linux-pci/20221202211838.1061278-1-helgaas@xxxxxxxxxx/ Bjorn > >> Link: https://bugzilla.kernel.org/show_bug.cgi?id=216565 > >> Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx> > >> --- > >> arch/x86/pci/acpi.c | 13 +++++++++++++ > >> 1 file changed, 13 insertions(+) > >> > >> diff --git a/arch/x86/pci/acpi.c b/arch/x86/pci/acpi.c > >> index 2f82480fd430..45ef65d31a40 100644 > >> --- a/arch/x86/pci/acpi.c > >> +++ b/arch/x86/pci/acpi.c > >> @@ -189,6 +189,19 @@ static const struct dmi_system_id pci_crs_quirks[] __initconst = { > >> DMI_MATCH(DMI_BOARD_NAME, "X170KM-G"), > >> }, > >> }, > >> + > >> + /* > >> + * Clevo NL4XLU barebones have the same E820 reservation covering > >> + * the entire _CRS 32-bit window issue as the Lenovo *IIL* models. > >> + * See https://bugzilla.kernel.org/show_bug.cgi?id=216565 > >> + */ > >> + { > >> + .callback = set_no_e820, > >> + .ident = "Clevo NL4XLU Barebone", > >> + .matches = { > >> + DMI_MATCH(DMI_BOARD_NAME, "NL4XLU"), > >> + }, > >> + }, > >> {} > >> }; > >> > >> -- > >> 2.37.3 > >> > > >
