Date: Mon, 9 Jun 2003 13:39:54 -0700
From: Greg KH <greg@kroah.com>
To: Daniel Phillips <dphillips@sistina.com>
Cc: dm-devel@sistina.com, Joe Thornber <thornber@sistina.com>,
       Linux Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [dm-devel] Re: [RFC] device-mapper ioctl interface
Message-ID: <20030609203954.GA8021@kroah.com>
References: <20030605093943.GD434@fib011235813.fsnet.co.uk> <20030606171700.GC12231@kroah.com> <200306092203.50024.dphillips@sistina.com>
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On Mon, Jun 09, 2003 at 10:03:50PM +0200, Daniel Phillips wrote:
> On Friday 06 June 2003 19:17, Greg KH wrote:
> > On Thu, Jun 05, 2003 at 10:39:43AM +0100, Joe Thornber wrote:
> > > Here's the header file for the the proposed new ioctl interface for
> > > dm.  We've tried to change as little as possible to minimise code
> > > changes in LVM2 and EVMS.
> >
> > Minor comment:
> > 	- please do not use uint_32t types in kernel header files.  Use
> > 	  the proper __u32 type which is guarenteed to be the proper
> > 	  size across the user/kernel boundry.
> 
> We even have a flavor without the __'s:
> 
>    http://lxr.linux.no/source/include/asm-i386/types.h?v=2.5.56#L47
> 
> A little easier on the eyes, imho.

But they are not the same.
 - "__" means this variable will be the same size across the
   kernel/userspace boundry.
 - without the "__" means this variable will only be this size within
   the kernel.

Use "__" for variables being seen by userspace.  Otherwise use the
types without "__".

Hope this helps,

greg k-h
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