On Wed, 12 Jan 2022 19:21:55 +1100 "Ard Biesheuvel" <ardb@xxxxxxxxxx> wrote: > What we might do is just use EFI 1.10 for all Apple x86 EFI machines. I have found logs of pre-T2 x86 Macs that have EFI v2.40 but I haven't heard of them having the issue with writing to nvram: [ 0.000000] efi: EFI v2.40 by Apple [ 0.000000] efi: ACPI=0x88ffe000 ACPI 2.0=0x88ffe014 SMBIOS=0x88f00000 SMBIOS 3.0=0x88efe000 [ 0.000000] secureboot: Secure boot disabled [ 0.000000] SMBIOS 3.0.0 present. [ 0.000000] DMI: Apple Inc. MacBookPro14,1/Mac-B4831CEBD52A0C4C, BIOS XXX.XXX.XXX.XXX.0 04/24/2020 MacBookPro14,1 [1], and MacBookPro13,1 [2] have EFI v2.40, but MacBookPro12,1 [3] has v1.10 [1] https://linux-hardware.org/?probe=b1b965bcfa&log=dmesg [2] https://linux-hardware.org/?probe=df102d9c8c&log=dmesg [3] https://linux-hardware.org/?probe=ef5195a62e&log=dmesg I don't know if this would mean the other Macs with EFI v2.40 would lose any functionality due to a patch like this (I'm not familiar with what was added to the runtime services between v1.10 and v2.40). > Please try the below: > > diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c > index ae79c3300129..2303f9b06412 100644 > --- a/drivers/firmware/efi/efi.c > +++ b/drivers/firmware/efi/efi.c > @@ -722,6 +722,13 @@ void __init efi_systab_report_header(const > efi_table_hdr_t *systab_hdr, > systab_hdr->revision >> 16, > systab_hdr->revision & 0xffff, > vendor); > + > + if (IS_ENABLED(CONFIG_X86_64) && > + systab_hdr->revision > EFI_1_10_SYSTEM_TABLE_REVISION && > + !strcmp(vendor, "Apple")) { > + pr_info("Apple EFI Mac detected, using EFI v1.10 > runtime services only\n"); > + efi.runtime_version = EFI_1_10_SYSTEM_TABLE_REVISION; > + } > } > > static __initdata char memory_type_name[][13] = { This patch makes writing to nvram work for me on MacBookPro16,1 --
