From: Michael Ellerman <mpe@ellerman.id.au>
To: LEROY Christophe <christophe.leroy@c-s.fr>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Paul Mackerras <paulus@samba.org>,
scottwood@freescale.com, sojkam1@fel.cvut.cz
Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org
Subject: Re: [v4,2/2] powerpc32: memset: only use dcbz once cache is enabled
Date: Thu, 17 Sep 2015 15:13:27 +1000 (AEST) [thread overview]
Message-ID: <20150917051328.00D411401DA@ozlabs.org> (raw)
In-Reply-To: <ca5390a60d9249e4a02ebf0b83009f3ceceba806.1442335197.git.christophe.leroy@c-s.fr>
On Wed, 2015-16-09 at 10:04:53 UTC, LEROY Christophe wrote:
> memset() uses instruction dcbz to speed up clearing by not wasting time
> loading cache line with data that will be overwritten.
> Some platform like mpc52xx do no have cache active at startup and
> can therefore not use memset(). Allthough no part of the code
> explicitly uses memset(), GCC may make calls to it.
>
> This patch modifies memset() such that at startup, memset()
> unconditionally skip the optimised bloc that uses dcbz instruction.
>
> Once the initial MMU is set up, in machine_init() we patch memset()
> by replacing this inconditional jump by a NOP
>
> Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Applied to powerpc fixes, thanks.
https://git.kernel.org/powerpc/c/400c47d81ca383fc87d5a393
cheers
prev parent reply other threads:[~2015-09-17 5:13 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-09-16 10:04 [PATCH v4 0/2] powerpc32: memcpy/memset: only use dcbz once cache is enabled Christophe Leroy
2015-09-16 10:04 ` [PATCH v4 1/2] powerpc32: memcpy: " Christophe Leroy
2015-09-17 5:13 ` [v4,1/2] " Michael Ellerman
2015-09-16 10:04 ` [PATCH v4 2/2] powerpc32: memset: " Christophe Leroy
2015-09-17 5:13 ` Michael Ellerman [this message]
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