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To: Paul Mackerras <paulus@samba.org>
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Cc: Andrew Morton <akpm@osdl.org>, linux-kernel@vger.kernel.org,
	linuxppc-embedded@ozlabs.org
Subject: Re: [PATCH][1/3] ppc32: add 440ep support
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On 27/07/05 18:56 -0400, Paul Mackerras wrote:
> Andrew Morton writes:
> 
> > Matt Porter <mporter@kernel.crashing.org> wrote:
> > >
> > > +static u64 dma_mask = 0xffffffffULL;

How about just DMA_32BIT_MASK from dma-mapping.h, that one has to be
correct. ;-)

> > 
> > I'm sure you're totally uninterested in this, but the above will probably
> > generate warnings on (say) ppc64, where u64 is implemented as unsigned
> > long.
> > 
> > I usually chuck a simple `-1' in there and the compiler always gets it
> > right, regardless of signedness and size and architecture.
> 
> Umm, I think we actually want 2^32-1 not -1, don't we?  In which case
> I think Matt's code is what we have to have.
> 
> I tried a little test compile with gcc 4.0 with -m64 -Wall and it
> didn't generate a warning with the 0xffffffffULL constant.