Messages in this thread | | | Subject | Re: [PATCH V3 1/2] ACPI / EC: Fix broken big-endian 64bit platforms using 'global_lock' | From | Sudeep Holla <> | Date | Wed, 23 Sep 2015 10:57:44 +0100 |
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On 23/09/15 10:39, Arnd Bergmann wrote: > On Wednesday 23 September 2015 10:15:42 Sudeep Holla wrote: >> On 15/09/15 09:34, Viresh Kumar wrote: >>> global_lock is defined as an unsigned long and accessing only its lower >>> 32 bits from sysfs is incorrect, as we need to consider other 32 bits >>> for big endian 64 bit systems. >>> >>> Fix that by making global_lock an u32 instead. >>> >>> Cc: <stable@vger.kernel.org> # v4.1+ >>> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> >>> >>> --- >>> Its marked just for # v4.1+, because arm64 has the first 64 big-endian >>> platform with ACPI. And ACPI support for that is mainlined recently >>> only (Arnd Bergmann). >>> >> >> Just to clarify, we don't support big-endian with ACPI on ARM64. >> We mandate use of EFI for ACPI on ARM64 and EFI spec mandates only >> little endian. >> > > EFI doesn't care what endianess the kernel has, as long as the > data structures are interpreted in the same way that the firmware > defines them, and I thought that at least UEFI on ARM64 with big-endian > is working in principle (if not, that is a bug that should be fixed). > > If ACPI is broken with big-endian kernels, we should probably add a > Kconfig statement to forbid it, like this: >
The diff looks sensible thing to have to avoid enabling ACPI with BE though I am not sure if this can be regarded as broken as it could be case of just not supported(my guess as I am not completely aware of the history).
Also I am not against the $subject patch as such, just added clarification so that it shouldn't be assumed that BE + ACPI works on ARM64.
Regards, Sudeep
> diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig > index 5d1015c26ff4..06cacc13e3d2 100644 > --- a/drivers/acpi/Kconfig > +++ b/drivers/acpi/Kconfig > @@ -6,6 +6,7 @@ menuconfig ACPI > bool "ACPI (Advanced Configuration and Power Interface) Support" > depends on !IA64_HP_SIM > depends on IA64 || X86 || (ARM64 && EXPERT) > + depends on !ARM64 || !CPU_BIG_ENDIAN || BROKEN > depends on PCI > select PNP > default y > > > Arnd >
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