linux-kernel - Re: [PATCH 13/17] x86-64: Remove pda

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Message-ID: <4972B0E3.8060200@kernel.org>
Date:	Sun, 18 Jan 2009 13:32:35 +0900
From:	Tejun Heo <tj@...nel.org>
To:	Brian Gerst <brgerst@...il.com>
CC:	Ingo Molnar <mingo@...e.hu>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 13/17] x86-64: Remove pda_init()

Hello,

Brian Gerst wrote:
> -void __cpuinit pda_init(int cpu)
> -{
> -	struct x8664_pda *pda = cpu_pda(cpu);
> -
> -	/* Setup up data that may be needed in __get_free_pages early */
> -	loadsegment(fs, 0);
> -	loadsegment(gs, 0);
> -
> -	load_pda_offset(cpu);
> -}

Simply removing these should work fine as they're also initialized in
other places earlier but I think they still need to be in cpu_init()
because...

/*
 * cpu_init() initializes state that is per-CPU. Some data is already
 * initialized (naturally) in the bootstrap process, such as the GDT
 * and IDT. We reload them nevertheless, this function acts as a
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^
 * 'CPU state barrier', nothing should get across.
 * A lot of state is already set up in PDA init for 64 bit
 */

Thanks.

-- 
tejun
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