linux-kernel - Re: [PATCH v3 1/6] arm64: cpufeature: Allow early detect of specific features

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Date:   Mon, 21 May 2018 13:06:44 +0100
From:   Daniel Thompson <daniel.thompson@...aro.org>
To:     Suzuki K Poulose <Suzuki.Poulose@....com>
Cc:     Julien Thierry <julien.thierry@....com>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        marc.zyngier@....com, mark.rutland@....com,
        christoffer.dall@....com, james.morse@....com, joelaf@...gle.com,
        joel.opensrc@...il.com, catalin.marinas@....com,
        will.deacon@....com
Subject: Re: [PATCH v3 1/6] arm64: cpufeature: Allow early detect of specific
 features

On Mon, May 21, 2018 at 12:45:22PM +0100, Suzuki K Poulose wrote:
> On 21/05/18 12:35, Julien Thierry wrote:
> > From: Daniel Thompson <daniel.thompson@...aro.org>
> > 
> > Currently it is not possible to detect features of the boot CPU
> > until the other CPUs have been brought up.
> > 
> > This prevents us from reacting to features of the boot CPU until
> > fairly late in the boot process. To solve this we allow a subset
> > of features (that are likely to be common to all clusters) to be
> > detected based on the boot CPU alone.
> > 
> > Signed-off-by: Daniel Thompson <daniel.thompson@...aro.org>
> > [julien.thierry@....com: check non-boot cpu missing early features, avoid
> > 			 duplicates between early features and normal
> > 			 features]
> > Signed-off-by: Julien Thierry <julien.thierry@....com>
> > Cc: Catalin Marinas <catalin.marinas@....com>
> > Cc: Will Deacon <will.deacon@....com>
> > Cc: Suzuki K Poulose <suzuki.poulose@....com>
> 
> nit: Since this is completely different from what Daniel started with,
> you could simply reset the author to yourself. The boot CPU feature was
> added keeping this user in mind.

Agree! It's no longer my patch.

If you want to retain any credit than Suggested-by: would make quite
sufficient.


Daniel.


> 
> The patch as such looks good to me.
> 
> Reviewed-by: Suzuki K Poulose <suzuki.poulose@....com>
> 
> > ---
> >   arch/arm64/kernel/cpufeature.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
> > index 9d1b06d..e03e897 100644
> > --- a/arch/arm64/kernel/cpufeature.c
> > +++ b/arch/arm64/kernel/cpufeature.c
> > @@ -1030,7 +1030,7 @@ static void cpu_copy_el2regs(const struct arm64_cpu_capabilities *__unused)
> >   	{
> >   		.desc = "GIC system register CPU interface",
> >   		.capability = ARM64_HAS_SYSREG_GIC_CPUIF,
> > -		.type = ARM64_CPUCAP_SYSTEM_FEATURE,
> > +		.type = ARM64_CPUCAP_STRICT_BOOT_CPU_FEATURE,
> >   		.matches = has_useable_gicv3_cpuif,
> >   		.sys_reg = SYS_ID_AA64PFR0_EL1,
> >   		.field_pos = ID_AA64PFR0_GIC_SHIFT,
> > --
> > 1.9.1
> > 
>