From: Russell King - ARM Linux <linux@arm.linux.org.uk>
To: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
Cc: Masahiro Yamada <yamada.m@jp.panasonic.com>,
Nicolas Pitre <nicolas.pitre@linaro.org>,
Kukjin Kim <kgene.kim@samsung.com>,
Heiko Stuebner <heiko@sntech.de>,
Sascha Hauer <s.hauer@pengutronix.de>,
Will Deacon <will.deacon@arm.com>,
linux-kernel@vger.kernel.org,
Ben Dooks <ben.dooks@codethink.co.uk>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH] ARM: decompressor: remove unused cache flush code
Date: Thu, 22 Jan 2015 15:44:00 +0000 [thread overview]
Message-ID: <20150122154400.GB26493@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <20150122080647.GX22880@pengutronix.de>
On Thu, Jan 22, 2015 at 09:06:47AM +0100, Uwe Kleine-König wrote:
> Hello,
>
> On Thu, Jan 22, 2015 at 02:22:58PM +0900, Masahiro Yamada wrote:
> > As ARM ARM says, the bit 19-16 of ID_MMFR1 is always 0b0000 because
> > ARMv7 requires a hierarchical cache implementation.
> > The line "mcr p15, 0, r10, c7, c14, 0" is not reachable.
> >
> > Moreover, the v7_flush_dcache_all in arch/arm/mm/cache-v7.S does not
> > check the ID_MMFR1.
> >
> > Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
> I stumbled about this some time ago, too. The thing is however that the
> __armv7_mmu_cache functions are selected if
> CPUID & 0x000f0000 == 0x000f0000, and that is (AFAIK at present only
> theoretically) not implying that we have an ARMv7 machine. Only that it
> uses the "CPUID Identification Scheme" which is required on ARMv7.
Correct, and there are ARMv6 CPUs which satisfy the "CPUID identification
scheme" test - and are probably not heirarchial.
--
FTTC broadband for 0.8mile line: currently at 10.5Mbps down 400kbps up
according to speedtest.net.
prev parent reply other threads:[~2015-01-22 15:44 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-01-22 5:22 Masahiro Yamada
2015-01-22 8:06 ` Uwe Kleine-König
2015-01-22 15:44 ` Russell King - ARM Linux [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20150122154400.GB26493@n2100.arm.linux.org.uk \
--to=linux@arm.linux.org.uk \
--cc=ben.dooks@codethink.co.uk \
--cc=heiko@sntech.de \
--cc=kgene.kim@samsung.com \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=nicolas.pitre@linaro.org \
--cc=s.hauer@pengutronix.de \
--cc=u.kleine-koenig@pengutronix.de \
--cc=will.deacon@arm.com \
--cc=yamada.m@jp.panasonic.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox
all inboxes | Powered by JetHome®