Messages in this thread Patch in this message | | | Date | Tue, 30 Jan 2018 14:56:37 +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 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 ;)
Cheers ---Dave
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