linux-kernel - Re: [PATCH] x86: do not expose CONFIG

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Message-ID: <20090130203712.GB1253@ucw.cz>
Date:	Fri, 30 Jan 2009 21:37:12 +0100
From:	Pavel Machek <pavel@...e.cz>
To:	Harvey Harrison <harvey.harrison@...il.com>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	"H. Peter Anvin" <hpa@...or.com>,
	"H. Peter Anvin" <hpa@...nel.org>, Arnd Bergmann <arnd@...db.de>,
	Jaswinder Singh Rajput <jaswinder@...nel.org>,
	Ingo Molnar <mingo@...e.hu>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Sam Ravnborg <sam@...nborg.org>,
	Jaswinder Singh Rajput <jaswinderrajput@...il.com>,
	"David S. Miller" <davem@...emloft.net>
Subject: Re: [PATCH] x86: do not expose CONFIG_BSWAP to userspace

On Wed 2009-01-28 14:40:44, Harvey Harrison wrote:
> On Wed, 2009-01-28 at 14:13 -0800, Linus Torvalds wrote:
> > 
> > On Wed, 28 Jan 2009, Harvey Harrison wrote:
> > >
> > > Use ifdef __i486__ to ensure the BSWAP instruction is available
> > > on 32-bit x86.
> > > 
> > > Signed-off-by: Harvey Harrison <harvey.harrison@...il.com>
> > > ---
> > > HPA,
> > > 
> > > I'm afraid my knowledge of gcc compiler flags for various models is
> > > lacking, I used i486 as suggested, just wanted to make sure I understood
> > > you corectly.
> > 
> > I really don't think this works.
> > 
> > Try this:
> > 
> > 	cpp -dM -m32 -march=pentium t.c | grep i486
> > 
> > and see the marked absense of __i486__ anywhere.
> > 
> > At least CONFIG_X86_BSWAP gives the right behaviour for the kernel.
> 
> You're right, it doesn't work.  Perhaps just exporting the bswap version
> all the time and i386-only people can worry about patching it out?

And break i386 in a nasty way? Please don't.
									Pavel


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