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Date: Mon, 21 Jan 2013 22:44:49 +0000
From: Russell King - ARM Linux <linux@arm.linux.org.uk>
To: John Stultz <john.stultz@linaro.org>
Cc: Arnd Bergmann <arnd@arndb.de>, Matt Sealey <matt@genesi-usa.com>,
        Linux ARM Kernel ML <linux-arm-kernel@lists.infradead.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@redhat.com>,
        Ben Dooks <ben@simtec.co.uk>
Subject: Re: One of these things (CONFIG_HZ) is not like the others..
Message-ID: <20130121224449.GZ23505@n2100.arm.linux.org.uk>
References: <CAKGA1bkiowcO7OPSfPmaB6eRj_3FNr+4ONnaQHEZkpxB2XfduQ@mail.gmail.com> <201301212041.17951.arnd@arndb.de> <50FDAC5F.4040605@linaro.org> <20130121211218.GX23505@n2100.arm.linux.org.uk> <50FDBEAC.2050606@linaro.org>
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On Mon, Jan 21, 2013 at 02:18:20PM -0800, John Stultz wrote:
> So we used to have the ACTHZ code to handle error from the HZ rate  
> requested and the HZ rate possible given the underlying hardware. That's  
> been moved to the register_refined_jiffies(), but do you have a sense if  
> there a reason it couldn't be used? I don't quite recall the bounds at  
> this second, so ~7% error might very well be too large.
>
> So yes, I suspect these sorts of platforms, where there are no modern  
> clocksource/clockevent driver, as well as further constraints (like  
> specific HZ) are likely not good candidates for a multi-arch build.

In this particular case, EBSA110 is not a candidate for multi-arch
build anyway, because it's ARMv4 and we're only really bothering with
ARMv6 and better.

Not only that, but the IO stuff on it is sufficiently obscure and
non-standard...