From: "Markus F.X.J. Oberhumer" <markus@oberhumer.com>
To: Christoph Hellwig <hch@infradead.org>,
Dave Rodgman <dave.rodgman@arm.com>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
nd <nd@arm.com>,
"herbert@gondor.apana.org.au" <herbert@gondor.apana.org.au>,
"davem@davemloft.net" <davem@davemloft.net>,
Matt Sealey <Matt.Sealey@arm.com>,
"nitingupta910@gmail.com" <nitingupta910@gmail.com>,
"rpurdie@openedhand.com" <rpurdie@openedhand.com>,
"minchan@kernel.org" <minchan@kernel.org>,
"sergey.senozhatsky.work@gmail.com"
<sergey.senozhatsky.work@gmail.com>
Subject: Re: [PATCH 2/6] lib/lzo: enable 64-bit CTZ on Arm
Date: Thu, 22 Nov 2018 04:06:15 +0100 [thread overview]
Message-ID: <5BF61D27.5000002@oberhumer.com> (raw)
In-Reply-To: <20181121173114.GA14352@infradead.org>
On 2018-11-21 18:31, Christoph Hellwig wrote:
>> #define LZO_USE_CTZ32 1
>> #elif defined(__i386__) || defined(__powerpc__)
>> #define LZO_USE_CTZ32 1
>> -#elif defined(__arm__) && (__LINUX_ARM_ARCH__ >= 5)
>> +#elif defined(__arm__)
>> +#if (__LINUX_ARM_ARCH__ >= 5)
>> #define LZO_USE_CTZ32 1
>> #endif
>> +#if (__LINUX_ARM_ARCH__ >= 6) && (CONFIG_THUMB2_KERNEL)
>> +#define LZO_USE_CTZ64 1
>
> All of this really needs to be driven by Kconfig symbols that
> the architecture selects instead of magic arch ifdefs here.
LZO_USE_CTZ32 and LZO_USE_CTZ64 should only be defined if there
is a *fast* hardware instruction.
It would be nice if there exists a kernel #define we could
use for detecting that.
--
Markus Oberhumer, <markus@oberhumer.com>, http://www.oberhumer.com/
next prev parent reply other threads:[~2018-11-22 3:06 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-21 11:59 [PATCH 1/6] lib/lzo: clean-up by introducing COPY16 Dave Rodgman
2018-11-21 11:59 ` [PATCH 2/6] lib/lzo: enable 64-bit CTZ on Arm Dave Rodgman
2018-11-21 17:31 ` Christoph Hellwig
2018-11-21 18:30 ` Matt Sealey
2018-11-22 3:06 ` Markus F.X.J. Oberhumer [this message]
2018-11-21 11:59 ` [PATCH 4/6] lib/lzo: fast 8-byte copy on arm64 Dave Rodgman
2018-11-21 11:59 ` [PATCH 3/6] lib/lzo: 64-bit CTZ on Arm aarch64 Dave Rodgman
2018-11-21 11:59 ` [PATCH 5/6] lib/lzo: implement run-length encoding Dave Rodgman
2018-11-21 11:59 ` [PATCH 6/6] lib/lzo: separate lzo-rle from lzo Dave Rodgman
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