From: Andi Kleen <ak@suse.de>
To: Rusty Russell <rusty@rustcorp.com.au>
Cc: davidm@hpl.hp.com, linux-kernel@vger.kernel.org,
torvalds@transmeta.com, rth@twiddle.net
Subject: Re: [PATCH] 2.5.1-pre5: per-cpu areas
Date: 14 Mar 2002 09:39:57 +0100 [thread overview]
Message-ID: <p73bsdrsftu.fsf@oldwotan.suse.de> (raw)
In-Reply-To: <15504.7958.677592.908691@napali.hpl.hp.com.suse.lists.linux.kernel> <E16lMzi-0002bb-00@wagner.rustcorp.com.au.suse.lists.linux.kernel>
In-Reply-To: Rusty Russell's message of "14 Mar 2002 05:37:11 +0100"
Rusty Russell <rusty@rustcorp.com.au> writes:
> In message <15504.7958.677592.908691@napali.hpl.hp.com> you write:
> > OK, I see this. Unfortunately, HIDE_RELOC() causes me problems
> > because it prevents me from taking the address of a per-CPU variable.
> > This is useful when you have a per-CPU structure (e.g., cpu_info).
> > Perhaps there should/could be a version of HIDE_RELOC() that doesn't
> > dereference the resulting address?
>
> Yep, valid point. Patch below: please play.
Please don't do that. I cannot easily take the address of a per CPU
variable on x86-64, or rather only with additional overhead. If you need the
address of one please use a different macro for that.
[on x86-64 per cpu data is referenced using a segment register, but
leaq %segreg:offset,%reg does not do the expected thing, it just loads
offset but doesn't add in the segment register base address. To get the
address I always need to fetch a pointer from the the per cpu data
that points to itself and work with that]
-Andi
next parent reply other threads:[~2002-03-14 8:40 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <15504.7958.677592.908691@napali.hpl.hp.com.suse.lists.linux.kernel>
[not found] ` <E16lMzi-0002bb-00@wagner.rustcorp.com.au.suse.lists.linux.kernel>
2002-03-14 8:39 ` Andi Kleen [this message]
2002-03-14 11:09 ` [PATCH] 2.5.1-pre5: per-cpu areas Rusty Russell
2002-03-14 11:14 ` Andi Kleen
2002-03-14 19:48 ` H. Peter Anvin
2002-03-14 18:04 ` David Mosberger
2002-03-14 18:51 ` Andi Kleen
2002-03-15 4:07 ` Rusty Russell
2002-03-15 9:13 ` Andi Kleen
2002-03-17 7:17 ` Rusty Russell
2002-03-18 7:35 ` Andi Kleen
2002-03-19 0:02 ` Rusty Russell
2002-03-19 0:08 ` J.A. Magallon
2002-03-19 0:15 ` Andi Kleen
2002-03-19 17:05 ` Richard Henderson
2002-03-15 4:19 ` David Mosberger
2002-03-15 5:52 ` Rusty Russell
[not found] <15504.7958.677592.908691@napali.hpl.hp.com>
2002-03-14 4:37 ` Rusty Russell
2002-03-14 5:05 ` Jeff Garzik
2002-03-14 11:14 ` Rusty Russell
2002-03-14 11:26 ` Jeff Garzik
2002-03-14 12:16 ` Rusty Russell
2002-03-14 12:25 ` Jeff Garzik
2002-03-15 1:00 ` Richard Henderson
2002-03-14 9:37 ` Richard Henderson
2002-03-14 18:06 ` David Mosberger
2001-12-05 22:09 Rusty Russell
2001-12-06 7:21 ` Keith Owens
2001-12-06 8:07 ` David S. Miller
2001-12-06 9:18 ` Chris Wedgwood
2001-12-07 15:03 ` Pavel Machek
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