linux-kernel - Re: [PATCH 4/5] arm64: Verify CPU errata work arounds on hotplugged CPU

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Date:	Fri, 15 Apr 2016 15:12:42 +0100
From:	Will Deacon <will.deacon@....com>
To:	Suzuki K Poulose <Suzuki.Poulose@....com>
Cc:	mark.rutland@....com, linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org, marc.zyngier@....com,
	catalin.marinas@....com, Vadim.Lomovtsev@...iumnetworks.com,
	Andre Przywara <andre.przywara@....com>
Subject: Re: [PATCH 4/5] arm64: Verify CPU errata work arounds on hotplugged
 CPU

On Fri, Apr 15, 2016 at 03:10:27PM +0100, Suzuki K Poulose wrote:
> On 14/04/16 18:49, Suzuki K Poulose wrote:
> >On 14/04/16 18:39, Will Deacon wrote:
> >>On Wed, Apr 06, 2016 at 12:24:13PM +0100, Suzuki K Poulose wrote:
> >>>CPU Errata work arounds are detected and applied to the
> >>>kernel code at boot time and the data is then freed up.
> >>>If a new hotplugged CPU requires a work around which
> >>>was not applied at boot time, there is nothing we can
> >>>do but simply fail the booting.
> >>
> >>Hmm, wouldn't it be better not to free the alternative text for errata
> >>workarounds instead?
> >
> >We could. I don't have a strong opinion. If there are no objections, I could
> >adopt it.
> 
> The alternatives have been merged to .init by :
> 
> commit 9aa4ec1571da6236 ("arm64: mm: fold alternatives into .init")
> 
> Mark,
> 
> Do you have any concerns on applying alternatives for CPUs turned online later ?
> We have to revert the patch above to get going

Well, note that I'm only suggesting that we keep the alternatives for
CPU errata workarounds.

Will