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Date: Tue, 13 Jan 2009 22:00:07 +0300
From: Cyrill Gorcunov <gorcunov@gmail.com>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: Harvey Harrison <harvey.harrison@gmail.com>, Ingo Molnar <mingo@elte.hu>,
       Thomas Gleixner <tglx@linutronix.de>, Sam Ravnborg <sam@ravnborg.org>,
       LKML <linux-kernel@vger.kernel.org>,
       Jaswinder Singh Rajput <jaswinderlinux@gmail.com>
Subject: Re: [PATCH -tip] x86: headers - fix export private data to
	userspace
Message-ID: <20090113190007.GA16663@localhost>
References: <20090113183456.GA14470@localhost> <1231871832.16221.1.camel@brick> <496CE234.2070900@zytor.com> <20090113185239.GC14470@localhost> <496CE3A2.4060605@zytor.com>
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[H. Peter Anvin - Tue, Jan 13, 2009 at 10:55:30AM -0800]
| 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.
| 

The thing is that kernel headers are not only touched by libc.
Someone could write a program and include setup.h there.
Or I translated you wrong :)

		- Cyrill -
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