Messages in this thread Patch in this message | | | Date | Fri, 26 Jan 2018 10:10:21 +0000 | From | Dave Martin <> | Subject | Re: [PATCH 05/16] arm64: Add flags to check the safety of a capability for late CPU |
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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
might be easier to understand.
[...]
Cheers ---Dave
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