linux-kernel - Re: [PATCH] Remove ARM errata Workarounds 458693 and 460075

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Message-ID: <20170418155725.GG27592@e104818-lin.cambridge.arm.com>
Date:   Tue, 18 Apr 2017 16:57:25 +0100
From:   Catalin Marinas <catalin.marinas@....com>
To:     Russell King - ARM Linux <linux@...linux.org.uk>
Cc:     Nisal Menuka <nisalmenuka23@...il.com>, vladimir.murzin@....com,
        linux-kernel@...r.kernel.org, dianders@...omium.org,
        kever.yang@...k-chips.com, armlinux@...isordat.com,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH] Remove ARM errata Workarounds 458693 and 460075

On Sun, Apr 16, 2017 at 09:04:46AM +0100, Russell King - ARM Linux wrote:
> On Sat, Apr 15, 2017 at 07:06:06PM -0500, Nisal Menuka wrote:
> > According to ARM, these errata exist only in a version of Cortex-A8
> > (r2p0) which was never built. Therefore, I believe there are no platforms
> > where this workaround should be enabled.
> > link :http://infocenter.arm.com/help/index.jsp?topic=
> > /com.arm.doc.faqs/ka15634.html
> 
> These were submitted by ARM Ltd back in 2009 - if the silicon was never
> built, there would've been no reason to submit them.  Maybe Catalin can
> shed some light on this, being the commit author who introduced these?

We normally try not to submit errata workarounds for revisions that are
not going to be built/deployed. It's possible that at the time there
were plans for r2p0 to be licensed and built (not just FPGA) but I don't
really remember the details. The A8 errata document indeed states that
r1p0 and r2p0 are obsolete but this can mean many things (like not
available to license).

I'll try to see if any of the A8 past product managers know anything
about this. In the meantime, I would leave them in (no run-time
overhead).

-- 
Catalin