From: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>
To: Marc Gonzalez <marc.w.gonzalez@free.fr>
Cc: Mark Rutland <mark.rutland@arm.com>,
MSM <linux-arm-msm@vger.kernel.org>,
"Suzuki K. Poulose" <suzuki.poulose@arm.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Linux ARM <linux-arm-kernel@lists.infradead.org>,
Ard Biesheuvel <ard.biesheuvel@linaro.org>,
linux-arm-kernel <linux-arm-kernel-bounces@lists.infradead.org>
Subject: Re: Relax CPU features sanity checking on heterogeneous architectures
Date: Fri, 11 Oct 2019 19:03:58 +0530 [thread overview]
Message-ID: <8fb6dce8dcda42a14c1347295a812a0f@codeaurora.org> (raw)
In-Reply-To: <a86e9be2-fc82-afea-5e94-b15d7eef1b84@free.fr>
On 2019-10-11 16:39, Marc Gonzalez wrote:
> On 11/10/2019 12:50, Mark Rutland wrote:
>
>> Before we make any changes, we need to check whether we do actually
>> handle this variation in a safe way, and we need to consider what this
>> means w.r.t. late CPU hotplug.
>>
>> Even if we can handle variation at boot time, once we've determined
>> the
>> set of system-wide features we cannot allow those to regress, and I
>> believe we'll need new code to enforce that. I don't think it's
>> sufficient to mark these as NONSTRICT, though we might do that with
>> other changes.
>>
>> We shouldn't look at the part number at all here. We care about
>> variation across CPUs regardless of whether this is big.LITTLE or some
>> variation in tie-offs, etc.
>
> See also the "Unexpected variation in SYS_ID_AA64MMFR0_EL1" thread
> from a year ago: (that was on msm8998)
>
> https://www.spinics.net/lists/arm-kernel/msg691242.html
>
I think, it was fixed by commit: 5717fe5ab38f ("arm64: cpufeature: Don't
treat granule sizes as strict")
Thanks,
Sai
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next prev parent reply other threads:[~2019-10-11 13:34 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-11 5:49 Relax CPU features sanity checking on heterogeneous architectures Sai Prakash Ranjan
2019-10-11 9:19 ` Marc Gonzalez
2019-10-11 9:57 ` Sai Prakash Ranjan
2019-10-11 10:50 ` Mark Rutland
2019-10-11 11:09 ` Marc Gonzalez
2019-10-11 13:33 ` Sai Prakash Ranjan [this message]
2019-10-11 13:17 ` Sai Prakash Ranjan
2019-10-11 13:34 ` Marc Zyngier
2019-10-11 13:40 ` Sai Prakash Ranjan
2019-10-17 20:00 ` Stephen Boyd
2019-10-18 7:20 ` Marc Zyngier
2019-10-18 14:33 ` Stephen Boyd
2019-10-18 16:40 ` Marc Zyngier
2019-10-18 10:18 ` Sai Prakash Ranjan
2019-10-11 13:33 ` Marc Zyngier
2019-10-11 13:54 ` Mark Rutland
2019-10-11 14:06 ` Marc Zyngier
2019-10-17 21:39 ` Jeremy Linton
2019-10-18 9:01 ` Catalin Marinas
2020-01-20 2:47 ` Sai Prakash Ranjan
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