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From: Timothy Miller <miller@techsource.com>
To: "Nakajima, Jun" <jun.nakajima@intel.com>
Cc: richard.brunner@amd.com, linux-kernel@vger.kernel.org
Subject: Re: Intel vs AMD64
Date: Thu, 26 Feb 2004 14:18:25 -0500	[thread overview]
Message-ID: <403E4681.20603@techsource.com> (raw)
In-Reply-To: <7F740D512C7C1046AB53446D37200173EA28A5@scsmsx402.sc.intel.com>



Nakajima, Jun wrote:
> Thanks for the clarification.
> 
> Yes, "implementation specific" is one of the differences between IA-32e
> and AMD64, i.e. that behavior is architecturally defined on AMD64, but
> on IA-32e (as I posted): 
>   Near branch with 66H prefix:
>     As documented in PRM the behavior is implementation specific and
> should 
>     avoid using 66H prefix on near branches.


In other words, Intel's implementation deviates from the architecture as 
defined by AMD.  So it's not 100% compatible.  I just want this point to 
be clear.


If these sorts of branches are common enough (and I suspect they are), 
then this sort of deviation could have a notable code-size (and L1) 
impact on code which is compiled to be compatible with both implementations.

Why did Intel decide to do that?


  parent reply	other threads:[~2004-02-26 19:08 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2004-02-26  5:32 Intel vs AMD64 Nakajima, Jun
2004-02-26 13:39 ` Chris Wedgwood
2004-02-26 14:35   ` Richard B. Johnson
2004-02-26 19:25     ` Timothy Miller
2004-02-26 19:46       ` Richard B. Johnson
2004-02-27 18:44   ` H. Peter Anvin
2004-02-26 19:18 ` Timothy Miller [this message]
2004-02-26 19:45   ` Scott Robert Ladd
2004-02-27 14:43     ` Timothy Miller
2004-03-03 17:34   ` Pavel Machek
     [not found] <7F740D512C7C1046AB53446D37200173EA28A5@scsmsx402.sc.intel.com.suse.lists.linux.kernel>
     [not found] ` <403E4681.20603@techsource.com.suse.lists.linux.kernel>
2004-02-26 20:17   ` Andi Kleen
2004-02-27 14:50     ` Timothy Miller
  -- strict thread matches above, loose matches on Subject: below --
2004-02-26  4:28 richard.brunner

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