Date: Fri, 29 Aug 2003 20:48:47 +0200
From: "J.A. Magallon" <jamagallon@able.es>
To: Antonio Vargas <wind@cocodriloo.com>
Cc: Lista Linux-Kernel <linux-kernel@vger.kernel.org>
Subject: Re: [2.4] gcc3 warns about type-punned pointers ?
Message-ID: <20030829184847.GA2069@werewolf.able.es>
References: <20030828223511.GA23528@werewolf.able.es> <20030829152418.GB709@wind.cocodriloo.com>
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On 08.29, Antonio Vargas wrote:
> On Fri, Aug 29, 2003 at 12:35:11AM +0200, J.A. Magallon wrote:
[...]
> > 
> > A collateral question: why is the reason for this function ?
> > long long assignments are not atomic in gcc ?
> 
> On x86, long long int == 64 bits but the chip is 32 bits wide,
> so it uses 2 separate memory accesses. There are 64bit-wide
> instructions which do bus-locking so that the are atomic,
> but gcc will not use them directly.
> 

I know, my question was why gcc does not generate cmpxchg8b on
a 64 bits assign. Or it should not ?

-- 
J.A. Magallon <jamagallon@able.es>      \                 Software is like sex:
werewolf.able.es                         \           It's better when it's free
Mandrake Linux release 9.2 (Cooker) for i586
Linux 2.4.22-jam1m (gcc 3.3.1 (Mandrake Linux 9.2 3.3.1-1mdk))
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