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

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Message-ID: <87fw914dr5.fsf@xmission.com>
Date:	Mon, 09 Jul 2012 00:03:58 -0700
From:	ebiederm@...ssion.com (Eric W. Biederman)
To:	Tejun Heo <tj@...nel.org>
Cc:	"H. Peter Anvin" <hpa@...or.com>,
	hacklu <embedway.linux@...il.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] x86, boot: Optimize the elf header handling.

Tejun Heo <tj@...nel.org> writes:

> Hello, guys.
>
> On Sun, Jul 01, 2012 at 11:37:22AM -0700, H. Peter Anvin wrote:
>> 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?
>
> I don't think the .data..percpu section needs 2M alignment.  The
> percpu data section is only used as init template and actual percpu
> addresses always go through offsetting against __per_cpu_offset[] - no
> matter what the vaddrs in the vmlinux are, they get offsetted into 2M
> aligned linear address if necessary.  I think the only alignment
> .data..percpu needs is cacheline alignment for separating its
> subsections.

Thanks.  My basic testing isn't showing any problems.

Of course all that changed was where in the vmlinux file not where
in physical memory the data was loaded, so problems would really
surprise me. 

Eric

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