Date: Tue, 17 Nov 2009 16:58:44 +0000
From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Mike Frysinger <vapier.adi@gmail.com>
Cc: Alan Cox <alan@linux.intel.com>,
       Linux kernel mailing list <linux-kernel@vger.kernel.org>
Subject: Re: [RESEND PATCH] gpio_addr_flash: Fix warnings
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On Tue, 17 Nov 2009 11:50:24 -0500
Mike Frysinger <vapier.adi@gmail.com> wrote:

> On Tue, Nov 17, 2009 at 10:46, Alan Cox wrote:
> > --- a/drivers/mtd/maps/gpio-addr-flash.c
> > +++ b/drivers/mtd/maps/gpio-addr-flash.c
> > - ? ? ? state->gpio_addrs ? ? = (void *)gpios->start;
> > + ? ? ? state->gpio_addrs ? ? = (void *)(unsigned long)gpios->start;
> > - ? ? ? state->map.virt ? ? ? = (void __iomem *)memory->start;
> > + ? ? ? state->map.virt ? ? ? = (void __iomem *)(unsigned long)memory->start;
> 
> on what system do you see warnings ?  start should be resource_size_t
> which should be phys_addr_t which should cast fine to a void*.

32bit x86 shows it up because resource_size_t is a physaddr_t which is
64bit (because of PAE). Now given you don't seem likely to be using the
top bits for any real world example that looks ok but really casting a
physical address to a pointer type needs care and the compiler can't
deduce your intent there.


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