linux-kernel - Re: [PATCH] modules: Use a better scheme for refcounting

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Message-Id: <200805190031.45136.rusty@rustcorp.com.au>
Date:	Mon, 19 May 2008 00:31:44 +1000
From:	Rusty Russell <rusty@...tcorp.com.au>
To:	Eric Dumazet <dada1@...mosbay.com>
Cc:	Mike Travis <travis@....com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux kernel <linux-kernel@...r.kernel.org>,
	Christoph Lameter <clameter@....com>
Subject: Re: [PATCH] modules: Use a better scheme for refcounting

On Saturday 17 May 2008 17:36:21 Eric Dumazet wrote:
> Christoph Lameter made good work last year and apparently the path is to :
>
> 1) Put pda at the begining of percpu section.

Well, we killed the pda on i386: it's basically a limited arch-specific percpu 
section.  Unfortunately, ISTR that doing so kills -fstack-protector on x86-64 
(gcc was explicitly patched to support the kernel doing this, but it nailed 
us to a fixed offset off %fs).  But the PDA is a redundant idea which should 
be removed.

> 2) Relocate percpu variables to begin at zero
> 3) Use %gs (or %fs) register to address pda AND percpu section.

Thanks for the prod Eric.  ISTR acking those patches; Christoph, what happened 
to them?

Cheers,
Rusty.
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