Messages in this thread | | | Date | Thu, 8 Sep 2016 14:40:25 +0100 | From | Catalin Marinas <> | Subject | Re: [PATCH v2 2/2] arm64: Use static keys for CPU features |
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On Wed, Sep 07, 2016 at 12:59:52PM -0400, Jason Baron wrote: > On 09/05/2016 01:25 PM, Catalin Marinas wrote: > > This patch adds static keys transparently for all the cpu_hwcaps > > features by implementing an array of default-false static keys and > > enabling them when detected. The cpus_have_cap() check uses the static > > keys if the feature being checked is a constant, otherwise the compiler > > generates the bitmap test. > > > > Because of the early call to static_branch_enable() via > > check_local_cpu_errata() -> update_cpu_capabilities(), the jump labels > > are initialised in cpuinfo_store_boot_cpu(). > > Was there a reason the jump_label_init() couldn't be moved > earlier in the common code?
No particular reason, only that I wasn't sure what the arch requirements to be able to initialise the jump labels early are (for example, jump_label_init() calls arch_jump_label_transform_static(); there don't seem to be any issues at a first look but I don't have the hardware to test and confirm). Therefore I followed the powerpc idea of calling jump_label_init() directly earlier.
We also don't know how early it needs to be to benefit other architectures (powerpc seems to call it on a very early path via early_setup()).
-- Catalin
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