linux-kernel - Re: [patch 16/19] x86 setup: handle boot loaders which set up the stack incorrectly

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Message-ID: <20071115164214.GF24087@suse.de>
Date:	Thu, 15 Nov 2007 08:42:14 -0800
From:	Greg KH <gregkh@...e.de>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [patch 16/19] x86 setup: handle boot loaders which set up the
	stack incorrectly

On Wed, Nov 14, 2007 at 11:27:01PM -0800, H. Peter Anvin wrote:
> Greg KH wrote:
>> -stable review patch.  If anyone has any objections, please let us know.
>> ------------------
>> From: H. Peter Anvin <hpa@...or.com>
>> patch 6b6815c6d5d1dc209701d1661a7a0e09a295db2f in mainline.
>> Apparently some specific versions of LILO enter the kernel with a
>> stack pointer that doesn't match the rest of the segments.  Make our
>> best attempt at untangling the resulting mess.
>> Signed-off-by: H. Peter Anvin <hpa@...or.com>
>> Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>
>
> Just FYI:
>
> It has been reported that while this patch fixes old LILO, and possibly 
> some other boot loaders (unknown), it has also broken older versions of 
> SYSLINUX: they still boot, but the command line is truncated (exactly how 
> much depends on the BIOS, but typical values are around 130 bytes.)
>
> This is definitely traceable to a bug in SYSLINUX that was already fixed in 
> release 3.50 (the current version of SYSLINUX is 3.52).
>
> I have chosen to leave the patch in mainline, rather than trying yet 
> another recipe and hope it doesn't break on some other random combination 
> of bootloaders, since:
>
> a) SYSLINUX is generally easily updated, compared to other bootloaders;
> b) The failure mode is less severe (it still boots.)
>
> ... however, you may choose to call differently.

I have no objection to keeping this patch in the tree, as it fixes a
real problem, and matches the upstream kernel version.

thanks,

greg k-h
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