linux-kernel - Re: [PATCH v3 11/12] x86, boot: add fields to support load bzImage and ramdisk high

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Message-ID: <50B104BC.90208@zytor.com>
Date:	Sat, 24 Nov 2012 09:32:44 -0800
From:	"H. Peter Anvin" <hpa@...or.com>
To:	"Eric W. Biederman" <ebiederm@...ssion.com>
CC:	Yinghai Lu <yinghai@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...e.hu>, linux-kernel@...r.kernel.org,
	Rob Landley <rob@...dley.net>,
	Matt Fleming <matt.fleming@...el.com>
Subject: Re: [PATCH v3 11/12] x86, boot: add fields to support load bzImage
 and ramdisk high

On 11/24/2012 04:37 AM, Eric W. Biederman wrote:
>
> Certainly /sbin/kexec isn't bothering to calculate the end of the setup
> header and just being far more conservative and using all of the 16bit
> real mode code as it's initializer.
>

That's not conservative... that's just plain wrong.  It means you're 
initializing the fields in struct boot_params with garbage instead of a 
predictable value (zero).

We could work around it with a sentinel hack... except you *also* 
probably modify *some* fields and now we have a horrid mix of 
initialized and uninitialized fields to sort out... and there really 
isn't any sane way for the kernel to sort that out.

We have a huge problem on our hands now because of it.

	-hpa

-- 
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.

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