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Subject: Re: [PATCH] x86: sparse errors from string_32.h
From: Harvey Harrison <harvey.harrison@gmail.com>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@elte.hu>, Thomas Gleixner <tglx@linutronix.de>,
       LKML <linux-kernel@vger.kernel.org>
In-Reply-To: <47A35FBB.5030003@zytor.com>
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	 <20080201105624.GD27178@elte.hu>  <47A35FBB.5030003@zytor.com>
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Date: Fri, 01 Feb 2008 16:40:15 -0800
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On Fri, 2008-02-01 at 10:06 -0800, H. Peter Anvin wrote:
> Ingo Molnar wrote:
> > * Harvey Harrison <harvey.harrison@gmail.com> wrote:
> > 
> >>  		case 1:
> >> -			*(unsigned char *)s = pattern;
> >> +			*(unsigned char *)s = pattern & 0xff;
> > 
> > i've applied your fix - but wouldnt it be cleaner to just cast the 
> > pattern variable to unsigned char instead?
> > 
> 
> Even better, since we're talking about fixed bytes, I suggest writing it as:
> 
> 	*(u8 *)s = (u8)pattern;
> 
> Much more compact and the intent is a little bit more obvious.
> 

While I agree that is cleaner, that will still produce sparse warnings
about a cast truncating bits from a constant value.  I think that
explicit & is necessary (unless the cure is worse than the disease).

Harvey