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Date: Wed, 27 Jul 2005 18:56:55 -0400
From: Paul Mackerras <paulus@samba.org>
To: Andrew Morton <akpm@osdl.org>
Cc: Matt Porter <mporter@kernel.crashing.org>, wfarnsworth@mvista.com,
       linuxppc-embedded@ozlabs.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH][1/3] ppc32: add 440ep support
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Andrew Morton writes:

> Matt Porter <mporter@kernel.crashing.org> wrote:
> >
> > +static u64 dma_mask = 0xffffffffULL;
> 
> 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.

Paul.