From: "H. J. Lu" <hjl@lucon.org>
To: Jan Beulich <jbeulich@novell.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>, Andi Kleen <ak@suse.de>,
Chuck Ebbert <76306.1226@compuserve.com>,
Andrew Morton <akpm@osdl.org>,
linux-kernel@vger.kernel.org, Zachary Amsden <zach@vmware.com>
Subject: Re: [PATCH RFC 3/6] Use %gs as the PDA base-segment in the kernel.
Date: Mon, 28 Aug 2006 07:54:36 -0700 [thread overview]
Message-ID: <20060828145436.GA5710@lucon.org> (raw)
In-Reply-To: <44F2D8A4.76E4.0078.0@novell.com>
On Mon, Aug 28, 2006 at 10:51:00AM +0100, Jan Beulich wrote:
> >>> Andi Kleen <ak@suse.de> 27.08.06 20:19 >>>
> >On Sunday 27 August 2006 19:20, Jeremy Fitzhardinge wrote:
> >> Andi Kleen wrote:
> >> >> +1: movw GS(%esp), %gs
> >> >>
> >> >
> >> > movl is recommended in 32bit mode
> >> >
> >>
> >> arch/i386/kernel/entry.S: Assembler messages:
> >> arch/i386/kernel/entry.S:334: Error: suffix or operands invalid for `mov'
> >
> >Looks like a gas bug to me.
>
> This was an intentional change (by H.J. if I recall right) as using movl
> with segment registers gives the incorrect impression that one gets a
> 32-bit memory access (especially for stores this is important, since
> there's really nothing stored to the upper 16 bits). One should always
> use suffix-less 'mov' for segment register accesses.
mov will generate the optimal opcode with old and new assemblers.
H.J.
next prev parent reply other threads:[~2006-08-28 14:54 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-08-27 8:44 [PATCH RFC 0/6] Implement per-processor data areas for i386 Jeremy Fitzhardinge
2006-08-27 8:44 ` [PATCH RFC 1/6] Basic definitions for i386-pda Jeremy Fitzhardinge
2006-08-27 8:44 ` [PATCH RFC 2/6] Initialize the per-CPU data area Jeremy Fitzhardinge
2006-08-27 8:44 ` [PATCH RFC 3/6] Use %gs as the PDA base-segment in the kernel Jeremy Fitzhardinge
2006-08-27 9:49 ` Keith Owens
2006-08-27 10:01 ` Jeremy Fitzhardinge
2006-08-27 15:57 ` Andi Kleen
2006-08-27 16:36 ` Jeremy Fitzhardinge
2006-08-27 17:20 ` Jeremy Fitzhardinge
2006-08-27 18:19 ` Andi Kleen
2006-08-27 20:03 ` Jan Engelhardt
2006-08-27 23:38 ` Jeremy Fitzhardinge
2006-08-28 9:51 ` Jan Beulich
2006-08-28 14:54 ` H. J. Lu [this message]
2006-08-28 17:24 ` H. Peter Anvin
2006-08-27 8:44 ` [PATCH RFC 4/6] Fix places where using %gs changes the usermode ABI Jeremy Fitzhardinge
2006-08-27 15:59 ` Andi Kleen
2006-08-27 16:37 ` Jeremy Fitzhardinge
2006-08-27 8:44 ` [PATCH RFC 5/6] Implement smp_processor_id() with the PDA Jeremy Fitzhardinge
2006-08-27 8:44 ` [PATCH RFC 6/6] Implement "current" " Jeremy Fitzhardinge
2006-08-27 16:01 ` Andi Kleen
2006-08-27 16:38 ` Jeremy Fitzhardinge
2006-08-27 9:47 ` [PATCH RFC 0/6] Implement per-processor data areas for i386 Arjan van de Ven
2006-08-27 16:46 ` Jeremy Fitzhardinge
2006-08-27 17:44 ` Arjan van de Ven
2006-08-27 18:07 ` Andi Kleen
2006-08-27 18:27 ` Jeremy Fitzhardinge
2006-08-27 16:01 ` Andi Kleen
2006-08-27 16:41 ` Jeremy Fitzhardinge
2006-08-27 17:21 ` Andreas Mohr
2006-08-27 17:34 ` Jeremy Fitzhardinge
2006-08-27 18:23 ` Andreas Mohr
2006-08-27 18:04 ` Andi Kleen
2006-08-27 18:27 ` Andreas Mohr
2006-08-27 18:35 ` Andi Kleen
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