linux-kernel - Re: [PATCH 2/2] x86, boot: Optimize the elf header handling.

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Message-ID: <4FF098E2.3040307@zytor.com>
Date:	Sun, 01 Jul 2012 11:37:22 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	"Eric W. Biederman" <ebiederm@...ssion.com>,
	Tejun Heo <tj@...nel.org>
CC:	hacklu <embedway.linux@...il.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] x86, boot: Optimize the elf header handling.

On 07/01/2012 11:25 AM, Eric W. Biederman wrote:
> 
> Well I see what is going on now.
> 
> In the vmlinux the paddrs and the poffsests stop tracking when they
> come to the percpu PT_LOAD segment.
> 
> It looks like we give the percpu segment a 4K alignment in memory
> and a 2M alignment in the file.
> 
> It looks like something is causing ld to compute an unfortunate physical
> load address for the percpu section.
> 
> At first glace I would say that is a bug.  Either we need the alignment
> or we don't.  But if we need the alignment we certainly need it to
> be respected for the real memory locations of the init symbols..
> 

If we don't need it, I think we can use -z max-page-size=4096, but we
use the PMD alignment for percpu on x86-64; Tejun, does that apply to
the .data..percpu section in the executable as well?

	-hpa

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