Messages in this thread | | | Subject | Re: [PATCH 05/16] arm64: Add flags to check the safety of a capability for late CPU | From | Suzuki K Poulose <> | Date | Tue, 30 Jan 2018 15:06:56 +0000 |
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On 30/01/18 14:56, Dave Martin wrote: > On Tue, Jan 30, 2018 at 11:17:38AM +0000, Suzuki K Poulose wrote: >> On 26/01/18 10:10, Dave Martin wrote: >>> On Tue, Jan 23, 2018 at 12:27:58PM +0000, Suzuki K Poulose wrote: >>>> Add two different flags to indicate if the conflict of a capability >>>> on a late CPU with the current system state >>>> >>>> 1) Can a CPU have a capability when the system doesn't have it ? >>>> >>>> Most arm64 features could have this set. While erratum work arounds >>>> cannot have this, as we may miss work arounds. >>>> >>>> 2) Can a CPU miss a capability when the system has it ? >>>> This could be set for arm64 erratum work arounds as we don't >>>> care if a CPU doesn't need the work around. However it should >>>> be clear for features. >>>> >>>> These flags could be added to certain entries based on their nature. >>>> >>>> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com> >>>> --- >>>> arch/arm64/include/asm/cpufeature.h | 35 +++++++++++++++++++++++++++++++---- >>>> 1 file changed, 31 insertions(+), 4 deletions(-) >>>> >>>> diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h >>>> index 4fd5de8ef33e..27d037bb0451 100644 >>>> --- a/arch/arm64/include/asm/cpufeature.h >>>> +++ b/arch/arm64/include/asm/cpufeature.h >>>> @@ -94,10 +94,25 @@ extern struct arm64_ftr_reg arm64_ftr_reg_ctrel0; >>>> #define SCOPE_SYSTEM ARM64_CPUCAP_SCOPE_SYSTEM >>>> #define SCOPE_LOCAL_CPU ARM64_CPUCAP_SCOPE_LOCAL_CPU >>>> -/* CPU errata detected at boot time based on feature of one or more CPUs */ >>>> -#define ARM64_CPUCAP_STRICT_CPU_LOCAL_ERRATUM (ARM64_CPUCAP_SCOPE_LOCAL_CPU) >>>> -/* CPU feature detected at boot time based on system-wide value of a feature */ >>>> -#define ARM64_CPUCAP_BOOT_SYSTEM_FEATURE (ARM64_CPUCAP_SCOPE_SYSTEM) >>>> +/* Is it safe for a late CPU to have this capability when system doesn't already have */ >>>> +#define ARM64_CPUCAP_LATE_CPU_SAFE_TO_HAVE BIT(2) >>>> +/* Is it safe for a late CPU to miss this capability when system has it */ >>>> +#define ARM64_CPUCAP_LATE_CPU_SAFE_TO_MISS BIT(3) >>> >>> Maybe _OPTIONAL and _PERMITTED would be a bit less verbose? >>> >>> Alternatively, >>> ARM64_CPUCAP_PERMITTED_FOR_LATE_CPU >>> ARM64_CPUCAP_OPTIONAL_FOR_LATE_CPU >> >> Sounds better than what I have. I have picked them up. > > Cool, I had resigned myself to probably not winning that one ;)
Well, you have won almost all in this series :-)
Cheers Suzuki
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