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

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Date:	Tue, 13 Jan 2009 11:05:07 -0800
From:	Harvey Harrison <harvey.harrison@...il.com>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	Cyrill Gorcunov <gorcunov@...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

On Tue, 2009-01-13 at 10:49 -0800, H. Peter Anvin wrote:
> Harvey Harrison wrote:
> > On Tue, 2009-01-13 at 21:34 +0300, Cyrill Gorcunov wrote:
> >> Impact: cleanup
> > 
> >> 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.
> 

Thanks for the explanation, while I was aware of that, I hadn't actually
looked if libc pulled this in...thinking a bit more it should have been
obvious libc wouldn't be interested in this header.

Thanks.

Harvey


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