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From: "H. Peter Anvin" <hpa@zytor.com>
To: Joe Perches <joe@perches.com>,
	mingo@kernel.org, linux-kernel@vger.kernel.org,
	tglx@linutronix.de, james.t.kukunas@intel.com,
	hpa@linux.intel.com,
	Linus Torvalds <torvalds@linux-foundation.org>
Cc: David Miller <davem@davemloft.net>
Subject: Re: [tip:x86/asm] x86, bitops:  Change bitops to be native operand size
Date: Sun, 10 Nov 2013 14:10:36 -0800	[thread overview]
Message-ID: <5ac67859-a0b2-47f5-bdc2-c2a52b8d6885@email.android.com> (raw)
In-Reply-To: <1384117768.3081.10.camel@joe-AO722>

Yes, on the generic it is int.

The problem is in part that some architectures have bitop instructions with specific behavior.

Joe Perches <joe@perches.com> wrote:
>On Tue, 2013-07-16 at 18:15 -0700, tip-bot for H. Peter Anvin wrote:
>> Commit-ID:  9b710506a03b01a9fdd83962912bc9d8237b82e8
>[]
>> x86, bitops: Change bitops to be native operand size
>> 
>> Change the bitops operation to be naturally "long", i.e. 63 bits on
>> the 64-bit kernel.  Additional bugs are likely to crop up in the
>> future.
>
>> We already have bugs which machines with > 16 TiB of memory in a
>> single node, as can happen if memory is interleaved.  The x86 bitop
>> operations take a signed index, so using an unsigned type is not an
>> option.
>
>I think it odd that any bitop index nr should be
>anything other than unsigned long for any arch.
>
>Why should this arch be any different than the
>defined type in Documentation/atomic_ops.txt?
>
>What value is a negative index when the bitmap
>array address passed is the starting 0th bit?
>
>btw: asm-generic/bitops.h doesn't match
>Documentation/atomic_ops.txt either.

-- 
Sent from my mobile phone.  Please pardon brevity and lack of formatting.

  reply	other threads:[~2013-11-10 22:16 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-07-17  1:15 tip-bot for H. Peter Anvin
2013-11-10 21:09 ` Joe Perches
2013-11-10 22:10   ` H. Peter Anvin [this message]
2013-11-10 22:44     ` Joe Perches
2013-11-11  2:06       ` H. Peter Anvin
2013-11-11  2:22         ` Joe Perches
2013-11-11 23:34           ` H. Peter Anvin
2013-11-12  2:54             ` Joe Perches
2013-11-12  3:15               ` Linus Torvalds
2013-11-12  4:08                 ` Joe Perches
2013-11-12  8:52                   ` Geert Uytterhoeven
2013-11-30 23:16                     ` Rob Landley

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