From: "H. Peter Anvin" <hpa@zytor.com>
To: Timothy Miller <miller@techsource.com>
Cc: "Nakajima, Jun" <jun.nakajima@intel.com>, linux-kernel@vger.kernel.org
Subject: Re: Intel vs AMD x86-64
Date: Wed, 25 Feb 2004 16:13:31 -0800 [thread overview]
Message-ID: <403D3A2B.40504@zytor.com> (raw)
In-Reply-To: <403D3379.60604@techsource.com>
Timothy Miller wrote:
>
>
> Nakajima, Jun wrote:
>
>> For near branches (CALL, RET, JCC, JCXZ, JMP, etc.), the operand size is
>> forced to 64 bits on both processors in 64-bit mode, basically meaning
>> RIP is updated.
>>
>> Compilers would typically use a JMP short for "intraprocedural jumps",
>> which requires just an 8-bit displacement relative to RIP.
>
> I see. It's too bad you can't have a 16-bit displacement.
>
> Ummm... so if 66H were used with a near branch, would that affect the
> size of the immediate operand which gets added to RIP, or would that
> affect the the portion of IP/EIP/RIP affected? If it's the latter,
> that's pretty silly.
>
Yes, that would be pretty silly.
I honestly don't remember off the top of my head what "o16 jmp blah"
does on i386; I have a vague memory that it zero-extends %eip to 32
bits, which makes it useless, of course.
-hpa
next prev parent reply other threads:[~2004-02-26 0:13 UTC|newest]
Thread overview: 79+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-02-25 20:07 Re: Intel vs AMD x86-64 Nakajima, Jun
2004-02-25 23:44 ` Timothy Miller
2004-02-26 0:13 ` H. Peter Anvin [this message]
-- strict thread matches above, loose matches on Subject: below --
2004-03-02 23:22 Nakajima, Jun
2004-02-26 1:19 Nakajima, Jun
2004-02-26 16:04 ` Timothy Miller
2004-02-27 3:16 ` Bill Davidsen
[not found] <1sRYA-1uZ-23@gated-at.bofh.it>
[not found] ` <1sSi2-1NC-5@gated-at.bofh.it>
[not found] ` <1sT4l-2CW-17@gated-at.bofh.it>
2004-02-25 15:41 ` Bill Davidsen
2004-02-25 16:08 ` Moritz Muehlenhoff
2004-02-25 3:24 Nakajima, Jun
2004-02-25 16:22 ` Timothy Miller
2004-02-25 16:17 ` H. Peter Anvin
2004-02-25 17:18 ` Timothy Miller
2004-02-25 17:16 ` H. Peter Anvin
2004-02-25 19:05 ` Timothy Miller
2004-02-25 3:07 Nakajima, Jun
[not found] <7F740D512C7C1046AB53446D37200173EA2684@scsmsx402.sc.intel.com.suse.lists.linux.kernel>
2004-02-24 23:49 ` Andi Kleen
2004-02-24 23:15 Nakajima, Jun
2004-02-25 1:52 ` Chris Wedgwood
2004-02-24 21:01 Sean Fao
2004-02-24 21:26 ` Linus Torvalds
2004-02-24 22:21 ` Timothy Miller
2004-02-25 22:30 ` Davide Rossetti
2004-02-24 21:31 ` Timothy Miller
2004-02-24 21:31 ` Linus Torvalds
2004-02-24 21:28 ` Dave Jones
2004-02-26 21:39 ` Kai Henningsen
2004-02-24 2:42 Albert Cahalan
2004-02-24 16:44 ` Dave Jones
2004-02-24 15:11 ` Albert Cahalan
2004-02-24 17:34 ` Dave Jones
2004-02-24 15:29 ` Albert Cahalan
2004-02-24 18:07 ` Dave Jones
2004-02-23 19:59 Xose Vazquez Perez
2004-02-23 18:10 Nakajima, Jun
2004-02-24 13:25 ` Pavel Machek
2004-02-18 21:28 Peter Maas
2004-02-18 21:26 Peter Maas
2004-02-18 1:44 Linus Torvalds
2004-02-18 9:56 ` Mikael Pettersson
2004-02-18 14:31 ` Diego Calleja García
2004-02-18 18:17 ` Bryan O'Sullivan
2004-02-18 14:54 ` Stefan Smietanowski
2004-02-18 15:47 ` Linus Torvalds
2004-02-22 2:59 ` Herbert Poetzl
2004-02-22 3:12 ` Linus Torvalds
2004-02-22 3:39 ` Tomasz Rola
2004-02-22 3:47 ` Mike Fedyk
2004-02-22 4:12 ` Scott Robert Ladd
2004-02-23 0:38 ` Timothy Miller
2004-02-23 2:17 ` Tom Vier
2004-02-22 8:38 ` Geert Uytterhoeven
2004-02-22 10:00 ` Vojtech Pavlik
2004-02-23 15:51 ` Clay Haapala
2004-02-23 17:03 ` Adrian Bunk
2004-02-23 17:31 ` Linus Torvalds
2004-02-24 9:47 ` Kees Bakker
2004-02-24 9:59 ` viro
2004-02-24 10:59 ` Andrew Walrond
2004-02-23 18:56 ` Christoph Hellwig
2004-02-23 21:25 ` Rik van Riel
2004-02-23 21:36 ` Linus Torvalds
2004-02-23 21:48 ` David S. Miller
2004-02-23 22:08 ` Linus Torvalds
2004-02-23 22:06 ` David S. Miller
2004-02-23 22:56 ` H. Peter Anvin
2004-02-24 1:01 ` Thomas Zehetbauer
2004-02-24 1:11 ` John Heil
2004-02-24 13:32 ` Timothy Miller
2004-02-24 14:39 ` Scott Robert Ladd
2004-02-24 19:43 ` Rogier Wolff
2004-02-24 19:49 ` John Heil
2004-02-24 20:03 ` Mike Fedyk
2004-02-24 20:03 ` John Heil
2004-02-24 21:20 ` Timothy Miller
2004-02-25 18:40 ` Matt Seitz
2004-02-18 19:13 ` Aaron Lehmann
2004-02-19 6:02 ` Mikael Pettersson
2004-02-19 9:15 ` Terje Eggestad
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