From: Andi Kleen <ak@suse.de>
To: Jakub Jelinek <jakub@redhat.com>
Cc: Zoltan Menyhart <Zoltan.Menyhart@bull.net>,
Jes Sorensen <jes@sgi.com>, Tony Luck <tony.luck@intel.com>,
discuss@x86-64.org, linux-kernel@vger.kernel.org,
libc-alpha@sourceware.org, vojtech@suse.cz,
linux-ia64@vger.kernel.org
Subject: Re: FOR REVIEW: New x86-64 vsyscall vgetcpu()
Date: Fri, 16 Jun 2006 16:24:52 +0000 [thread overview]
Message-ID: <200606161824.52620.ak@suse.de> (raw)
In-Reply-To: <20060616155804.GN3823@sunsite.mff.cuni.cz>
On Friday 16 June 2006 17:58, Jakub Jelinek wrote:
> On Fri, Jun 16, 2006 at 05:37:06PM +0200, Andi Kleen wrote:
> > On Friday 16 June 2006 17:31, Zoltan Menyhart wrote:
> > > Andi Kleen wrote:
> > >
> > > > That is not how user space TLS works. It usually has a base a register.
> > >
> > > Can you please give me a real life (simplified) example?
> >
> > On x86-64 it's just %fs:offset. gcc is a bit dumb on this and usually
> > loads the base address from %fs:0 first.
>
> GCC is not dumb, unless you force it with -mno-tls-direct-seg-refs.
> Guess you are bitten by SUSE GCC hack which makes -mno-tls-direct-seg-refs
> the default (especially on x86-64 it is a really bad idea).
I apparently got indeed.
I wonder why it happened on x86-64 though - i thought there were no negative
offsets on x86-64 TLS.
-Andi
WARNING: multiple messages have this Message-ID (diff)
From: Andi Kleen <ak@suse.de>
To: Jakub Jelinek <jakub@redhat.com>
Cc: Zoltan Menyhart <Zoltan.Menyhart@bull.net>,
Jes Sorensen <jes@sgi.com>, Tony Luck <tony.luck@intel.com>,
discuss@x86-64.org, linux-kernel@vger.kernel.org,
libc-alpha@sourceware.org, vojtech@suse.cz,
linux-ia64@vger.kernel.org
Subject: Re: FOR REVIEW: New x86-64 vsyscall vgetcpu()
Date: Fri, 16 Jun 2006 18:24:52 +0200 [thread overview]
Message-ID: <200606161824.52620.ak@suse.de> (raw)
In-Reply-To: <20060616155804.GN3823@sunsite.mff.cuni.cz>
On Friday 16 June 2006 17:58, Jakub Jelinek wrote:
> On Fri, Jun 16, 2006 at 05:37:06PM +0200, Andi Kleen wrote:
> > On Friday 16 June 2006 17:31, Zoltan Menyhart wrote:
> > > Andi Kleen wrote:
> > >
> > > > That is not how user space TLS works. It usually has a base a register.
> > >
> > > Can you please give me a real life (simplified) example?
> >
> > On x86-64 it's just %fs:offset. gcc is a bit dumb on this and usually
> > loads the base address from %fs:0 first.
>
> GCC is not dumb, unless you force it with -mno-tls-direct-seg-refs.
> Guess you are bitten by SUSE GCC hack which makes -mno-tls-direct-seg-refs
> the default (especially on x86-64 it is a really bad idea).
I apparently got indeed.
I wonder why it happened on x86-64 though - i thought there were no negative
offsets on x86-64 TLS.
-Andi
next prev parent reply other threads:[~2006-06-16 16:24 UTC|newest]
Thread overview: 69+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-06-14 7:42 FOR REVIEW: New x86-64 vsyscall vgetcpu() Andi Kleen
2006-06-14 10:47 ` Alan Cox
2006-06-14 14:54 ` Steve Munroe
2006-06-15 23:17 ` Benjamin Herrenschmidt
[not found] ` <449029DB.7030505@redhat.com>
[not found] ` <200606141752.02361.ak@suse.de>
2006-06-14 16:30 ` Ulrich Drepper
2006-06-14 17:34 ` [discuss] " Andi Kleen
2006-06-15 18:44 ` Tony Luck
2006-06-16 6:22 ` Andi Kleen
2006-06-16 7:23 ` Gerd Hoffmann
2006-06-16 7:37 ` Andi Kleen
2006-06-16 9:48 ` Jes Sorensen
2006-06-16 9:48 ` Jes Sorensen
2006-06-16 10:09 ` Andi Kleen
2006-06-16 10:09 ` Andi Kleen
2006-06-16 11:02 ` Jes Sorensen
2006-06-16 11:02 ` Jes Sorensen
2006-06-16 11:17 ` Andi Kleen
2006-06-16 11:17 ` Andi Kleen
2006-06-16 11:58 ` Jes Sorensen
2006-06-16 11:58 ` Jes Sorensen
2006-06-16 12:36 ` Zoltan Menyhart
2006-06-16 12:36 ` Zoltan Menyhart
2006-06-16 12:41 ` Jes Sorensen
2006-06-16 12:41 ` Jes Sorensen
2006-06-16 12:48 ` Zoltan Menyhart
2006-06-16 12:48 ` Zoltan Menyhart
2006-06-16 21:04 ` Chase Venters
2006-06-16 21:04 ` Chase Venters
2006-06-16 14:56 ` Andi Kleen
2006-06-16 14:56 ` Andi Kleen
2006-06-16 15:31 ` Zoltan Menyhart
2006-06-16 15:31 ` Zoltan Menyhart
2006-06-16 15:37 ` Andi Kleen
2006-06-16 15:37 ` Andi Kleen
2006-06-16 15:58 ` Jakub Jelinek
2006-06-16 15:58 ` Jakub Jelinek
2006-06-16 16:24 ` Andi Kleen [this message]
2006-06-16 16:24 ` Andi Kleen
2006-06-16 16:33 ` Jakub Jelinek
2006-06-16 16:33 ` Jakub Jelinek
2006-06-16 21:12 ` Chase Venters
2006-06-16 21:12 ` Chase Venters
2006-06-16 15:36 ` Brent Casavant
2006-06-16 15:36 ` Brent Casavant
2006-06-16 15:40 ` Andi Kleen
2006-06-16 15:40 ` Andi Kleen
2006-06-16 21:15 ` Chase Venters
2006-06-16 21:15 ` Chase Venters
2006-06-16 21:19 ` Chase Venters
2006-06-16 21:19 ` Chase Venters
2006-06-16 23:40 ` Brent Casavant
2006-06-16 23:40 ` Brent Casavant
2006-06-17 6:58 ` Andi Kleen
2006-06-17 6:58 ` Andi Kleen
2006-06-17 6:55 ` [discuss] " Andi Kleen
2006-06-17 6:55 ` Andi Kleen
2006-06-19 8:42 ` Zoltan Menyhart
2006-06-19 8:42 ` Zoltan Menyhart
2006-06-19 8:54 ` Andi Kleen
2006-06-19 8:54 ` Andi Kleen
2006-06-16 14:54 ` Andi Kleen
2006-06-16 14:54 ` Andi Kleen
2006-06-20 8:28 ` Jes Sorensen
2006-06-20 8:28 ` Jes Sorensen
2006-06-19 0:15 ` Paul Jackson
2006-06-19 8:21 ` Andi Kleen
2006-06-19 10:09 ` Paul Jackson
2006-06-21 1:18 ` Paul Jackson
2006-06-21 1:21 ` Paul Jackson
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