From: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
To: Sascha Hauer <s.hauer@pengutronix.de>
Cc: barebox@lists.infradead.org
Subject: Re: sparse warnings
Date: Thu, 18 Nov 2010 11:22:06 +0100 [thread overview]
Message-ID: <20101118102206.GL8942@pengutronix.de> (raw)
In-Reply-To: <20101118100133.GU6017@pengutronix.de>
On Thu, Nov 18, 2010 at 11:01:33AM +0100, Sascha Hauer wrote:
> On Thu, Nov 18, 2010 at 10:36:51AM +0100, Belisko Marek wrote:
> > Hi,
> >
> > On Wed, Nov 17, 2010 at 10:11 AM, Sascha Hauer <s.hauer@pengutronix.de> wrote:
> > > Hi Marek,
> > >
> > > On Mon, Nov 15, 2010 at 03:20:47PM +0100, Belisko Marek wrote:
> > >> Hi,
> > >>
> > >> barebox compilation with C=1 produce a lot of sparse warnings.
> > >> Mainly concerning __iomem problems with readb() and similar functions.
> > >>
> > >> Make it sense to take care or just could be omitted?
> > >
> > > I think it makes sense to work on this. Then we can see the useful
> > > warnings buried under the __iomem warnings.
> > >
> > > I had the idea of adding a
> > >
> > > #define IOMEM(addr) ((void __force __iomem *)(addr))
> > >
> > > and use it where appropriate.
> > Maybe stupid question but couldn't be __iomem mechanism removed completely?
> > Do we need to check for different address_space? In my opinion it
> > makes no sense in
> > barebox.
>
> I have a better feeling letting it in. There may be no different address
> spaces on Arm, but there are for exmample on x86.
> You can simply do a #define __iomem in include/linux/compiler.h to
> silence these kinds of warnings temporarily if you are not interested.
> I agree that at least on Arm these warnings will not reveal any real
> bugs.
I can imagine you to get hard to find bugs if you interpret a pointer to
registers as normal pointer without volatile. Something like:
unsigned long *register = 0xabcdef04;
while (*register & SOME_FLAG)
/* nothing */
This might generate code that corresponds to
if (*register & SOME_FLAG)
while(1);
So I feel for letting it in, too.
Best regards
Uwe
--
Pengutronix e.K. | Uwe Kleine-König |
Industrial Linux Solutions | http://www.pengutronix.de/ |
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prev parent reply other threads:[~2010-11-18 10:22 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-11-15 14:20 Belisko Marek
2010-11-17 9:11 ` Sascha Hauer
2010-11-18 9:36 ` Belisko Marek
2010-11-18 10:01 ` Sascha Hauer
2010-11-18 10:22 ` Uwe Kleine-König [this message]
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