From: Catalin Marinas <catalin.marinas@arm.com>
To: Will Deacon <will@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>,
khilman@baylibre.com, Suzuki Poulose <suzuki.poulose@arm.com>,
linux-arm-kernel@lists.infradead.org,
Marc Zyngier <maz@kernel.org>
Subject: Re: [PATCH] arm64: cpufeature: Don't treat granule sizes as strict
Date: Tue, 13 Aug 2019 12:59:45 +0100 [thread overview]
Message-ID: <20190813115944.GI62772@arrakis.emea.arm.com> (raw)
In-Reply-To: <20190812150225.25386-1-will@kernel.org>
On Mon, Aug 12, 2019 at 04:02:25PM +0100, Will Deacon wrote:
> If a CPU doesn't support the page size for which the kernel is
> configured, then we will complain and refuse to bring it online. For
> secondary CPUs (and the boot CPU on a system booting with EFI), we will
> also print an error identifying the mismatch.
>
> Consequently, the only time that the cpufeature code can detect a
> granule size mismatch is for a granule other than the one that is
> currently being used. Although we would rather such systems didn't
> exist, we've unfortunately lost that battle and Kevin reports that
> on his amlogic S922X (odroid-n2 board) we end up warning and taining
> with defconfig because 16k pages are not supported by all of the CPUs.
>
> In such a situation, we don't actually care about the feature mismatch,
> particularly now that KVM only exposes the sanitised view of the CPU
> registers. Treat the granule fields as non-strict and let Kevin run
> without a tainted kernel.
>
> Cc: Mark Rutland <mark.rutland@arm.com>
> Cc: Marc Zyngier <maz@kernel.org>
> Cc: Suzuki Poulose <suzuki.poulose@arm.com>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Reported-by: Kevin Hilman <khilman@baylibre.com>
> Signed-off-by: Will Deacon <will@kernel.org>
Queued for 5.3-rc5. Thanks.
--
Catalin
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prev parent reply other threads:[~2019-08-13 11:59 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-12 15:02 [PATCH] arm64: cpufeature: Don't treat granule sizes as strict Will Deacon
2019-08-12 15:04 ` Mark Rutland
2019-08-12 15:48 ` Suzuki K Poulose
2019-08-12 20:57 ` Kevin Hilman
2019-08-13 11:59 ` Catalin Marinas [this message]
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