From: Brian Gerst <bgerst@didntduck.org>
To: "Jörn Engel" <joern@wohnheim.fh-wedel.de>
Cc: Linus Torvalds <torvalds@osdl.org>,
Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: Being more anal about iospace accesses..
Date: Wed, 15 Sep 2004 13:40:59 -0400 [thread overview]
Message-ID: <41487EAB.1000004@didntduck.org> (raw)
In-Reply-To: <20040915165450.GD6158@wohnheim.fh-wedel.de>
Jörn Engel wrote:
> On Wed, 15 September 2004 09:30:42 -0700, Linus Torvalds wrote:
>
>>For example, if you don't know (or, more importantly - don't care) what
>>kind of IO interface you use, you can now do something like
>>
>> void __iomem * map = pci_iomap(dev, bar, maxbytes);
>> ...
>> status = ioread32(map + DRIVER_STATUS_OFFSET);
>
>
> C now supports pointer arithmetic with void*? I hope the width of a
> void is not architecture dependent, that would introduce more subtle
> bugs.
>
> Jörn
>
http://gcc.gnu.org/onlinedocs/gcc-3.4.2/gcc/Pointer-Arith.html#Pointer-Arith
5.18 Arithmetic on void- and Function-Pointers
In GNU C, addition and subtraction operations are supported on pointers
to void and on pointers to functions. This is done by treating the size
of a void or of a function as 1.
A consequence of this is that sizeof is also allowed on void and on
function types, and returns 1.
The option -Wpointer-arith requests a warning if these extensions are used.
--
Brian Gerst
next prev parent reply other threads:[~2004-09-15 17:42 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <Pine.LNX.4.58.0409081543320.5912@ppc970.osdl.org>
[not found] ` <Pine.LNX.4.58.0409150737260.2333@ppc970.osdl.org>
2004-09-15 16:30 ` Being more anal about iospace accesses Linus Torvalds
2004-09-15 16:54 ` Jörn Engel
2004-09-15 17:07 ` Linus Torvalds
2004-09-15 17:32 ` Jörn Engel
2004-09-15 17:57 ` Linus Torvalds
2004-09-15 18:06 ` Linus Torvalds
2004-09-15 19:34 ` Greg KH
2004-09-15 19:53 ` Linus Torvalds
2004-09-15 20:06 ` Greg KH
2004-09-16 14:58 ` Horst von Brand
2004-09-15 17:45 ` Nikita Danilov
2004-09-15 18:09 ` Linus Torvalds
2004-09-15 18:40 ` Chris Wedgwood
2004-09-15 17:07 ` Jeff Garzik
2004-09-15 17:16 ` Roland Dreier
2004-09-15 17:39 ` Linus Torvalds
2004-09-15 20:07 ` Russell King
2004-09-15 17:36 ` Horst von Brand
2004-09-15 17:40 ` Brian Gerst [this message]
2004-09-15 16:56 ` Dave Jones
2004-09-15 17:19 ` Roger Luethi
2004-09-15 17:23 ` Richard B. Johnson
2004-09-15 22:21 ` Deepak Saxena
2004-09-15 22:46 ` Linus Torvalds
2004-09-15 23:09 ` Deepak Saxena
2004-09-16 12:51 ` Geert Uytterhoeven
2004-09-16 22:10 ` Deepak Saxena
2004-09-15 22:29 ` Roland Dreier
2004-09-15 23:26 ` Being more careful " Linus Torvalds
2004-09-16 0:10 ` viro
2004-09-16 11:40 ` David Woodhouse
2004-09-16 12:25 ` David Woodhouse
2004-09-16 14:01 ` Linus Torvalds
2004-09-18 9:46 ` Kai Henningsen
2004-09-15 18:25 Being more anal " linux
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