On 2019/6/19 20:18, Ard Biesheuvel wrote: > Some Qualcomm Snapdragon based laptops built to run Microsoft Windows > are clearly ACPI 5.1 based, given that that is the first ACPI revision > that supports ARM, and introduced the FADT 'arm_boot_flags' field, > which has a non-zero field on those systems. > > So in these cases, infer from the ARM boot flags that the FADT must be > 5.1 or later, and treat it as 5.1. > > Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx> > --- > arch/arm64/kernel/acpi.c | 10 +++++++--- > 1 file changed, 7 insertions(+), 3 deletions(-) > > diff --git a/arch/arm64/kernel/acpi.c b/arch/arm64/kernel/acpi.c > index 803f0494dd3e..7722e85fb69c 100644 > --- a/arch/arm64/kernel/acpi.c > +++ b/arch/arm64/kernel/acpi.c > @@ -155,10 +155,14 @@ static int __init acpi_fadt_sanity_check(void) > */ > if (table->revision < 5 || > (table->revision == 5 && fadt->minor_revision < 1)) { > - pr_err("Unsupported FADT revision %d.%d, should be 5.1+\n", > + pr_err(FW_BUG "Unsupported FADT revision %d.%d, should be 5.1+\n", > table->revision, fadt->minor_revision); > - ret = -EINVAL; > - goto out; > + > + if (!fadt->arm_boot_flags) { > + ret = -EINVAL; > + goto out; > + } > + pr_err("FADT has ARM boot flags set, assuming 5.1\n"); Obviously it's a firmware bug, but should be harmless, Acked-by: Hanjun Guo <guohanjun@xxxxxxxxxx> Thanks Hanjun