linux-kernel - Re: [PATCH -tip] x86: headers - fix export private data to userspace

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Date:	Tue, 13 Jan 2009 10:55:30 -0800
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Cyrill Gorcunov <gorcunov@...il.com>
CC:	Harvey Harrison <harvey.harrison@...il.com>,
	Ingo Molnar <mingo@...e.hu>,
	Thomas Gleixner <tglx@...utronix.de>,
	Sam Ravnborg <sam@...nborg.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Jaswinder Singh Rajput <jaswinderlinux@...il.com>
Subject: Re: [PATCH -tip] x86: headers - fix export private data to	userspace

Cyrill Gorcunov wrote:
> | > 
> | >> 4) setup.h - COMMAND_LINE_SIZE saved for userspace, bootloaders
> | >>    could use it.
> | > 
> | > Doesn't this need to be (at least) _COMMAND_LINE_SIZE to avoid
> | > polluting the namespace, not sure it can be changed though as the
> | > horse is already out of the barn.
> | 
> | No, this is not one of those cases, but it's worth explaining why.
> | 
> | You can introduce symbols into the general namespace if *and only if*
> | they are in a header file that is invoked directly by the user.  In
> | other words, such a header file is unusable by libc, but setup.h doesn't
> | contain anything needed by libc in the first place.
> | 
> | 	-hpa
> | 
> 
> So we could just fence it by __KERNEL__?
> 

We might, as userspace shouldn't need COMMAND_LINE_SIZE anyway (see
other post), but I'm rather confused as how you got that from what I
wrote above.

	-hpa

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

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