From: Segher Boessenkool <segher@kernel.crashing.org>
To: Arnd Bergmann <arnd@kernel.org>
Cc: linux-arch@vger.kernel.org, Arnd Bergmann <arnd@arndb.de>,
Vineet Gupta <vgupta@synopsys.com>,
linux-kernel@vger.kernel.org,
Linus Torvalds <torvalds@linux-foundation.org>,
Paul Mackerras <paulus@samba.org>,
linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH v2 05/13] powerpc: use linux/unaligned/le_struct.h on LE power7
Date: Fri, 14 May 2021 06:48:13 -0500 [thread overview]
Message-ID: <20210514114813.GJ10366@gate.crashing.org> (raw)
In-Reply-To: <20210514100106.3404011-6-arnd@kernel.org>
Hi Arnd,
On Fri, May 14, 2021 at 12:00:53PM +0200, Arnd Bergmann wrote:
> Little-endian POWER7 kernels disable
> CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS because that is not supported on
> the hardware, but the kernel still uses direct load/store for explicti
> get_unaligned()/put_unaligned().
>
> I assume this is a mistake that leads to power7 having to trap and fix
> up all these unaligned accesses at a noticeable performance cost.
>
> The fix is completely trivial, just remove the file and use the
> generic version that gets it right.
LE p7 isn't supported (it requires special firmware), and no one uses it
anymore, also not for development. It was used for powerpc64le-linux
development before p8 was widely available.
Segher
next prev parent reply other threads:[~2021-05-14 11:50 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-14 10:00 [PATCH v2 00/13] Unify asm/unaligned.h around struct helper Arnd Bergmann
2021-05-14 10:00 ` [PATCH v2 05/13] powerpc: use linux/unaligned/le_struct.h on LE power7 Arnd Bergmann
2021-05-14 11:48 ` Segher Boessenkool [this message]
2021-05-14 13:02 ` Arnd Bergmann
2021-05-14 17:32 ` [PATCH v2 00/13] Unify asm/unaligned.h around struct helper Linus Torvalds
2021-05-14 18:51 ` Vineet Gupta
2021-05-14 19:22 ` Linus Torvalds
2021-05-14 19:45 ` Vineet Gupta
2021-05-14 20:19 ` Linus Torvalds
2021-05-14 19:31 ` Arnd Bergmann
2021-12-16 17:29 ` Ard Biesheuvel
2021-12-16 17:42 ` Linus Torvalds
2021-12-16 17:49 ` David Laight
2021-12-16 18:56 ` Segher Boessenkool
2021-12-17 12:34 ` David Laight
2021-12-17 13:35 ` Segher Boessenkool
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