This is an archived copy of the Xen.org mailing list, which we have preserved to ensure that existing links to archives are not broken. The live archive, which contains the latest emails, can be found at http://lists.xen.org/
Home Products Support Community News


Re: [Xen-devel] Re: [patch] fix void* arithmetic

To: Hollis Blanchard <hollisb@xxxxxxxxxx>
Subject: Re: [Xen-devel] Re: [patch] fix void* arithmetic
From: Jeff Garzik <jeff@xxxxxxxxxx>
Date: Tue, 29 Aug 2006 17:26:28 -0400
Cc: xen-ppc-devel <xen-ppc-devel@xxxxxxxxxxxxxxxxxxx>, xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx>, Ian Campbell <Ian.Campbell@xxxxxxxxxxxxx>
Delivery-date: Tue, 29 Aug 2006 14:27:15 -0700
Envelope-to: www-data@xxxxxxxxxxxxxxxxxx
In-reply-to: <1156886315.29858.78.camel@xxxxxxxxxxxxxxxxxxxxx>
List-help: <mailto:xen-devel-request@lists.xensource.com?subject=help>
List-id: Xen developer discussion <xen-devel.lists.xensource.com>
List-post: <mailto:xen-devel@lists.xensource.com>
List-subscribe: <http://lists.xensource.com/cgi-bin/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=subscribe>
List-unsubscribe: <http://lists.xensource.com/cgi-bin/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe>
References: <1156883088.29858.69.camel@xxxxxxxxxxxxxxxxxxxxx> <1156885583.5190.9.camel@xxxxxxxxxxxxxxxxxxxxx> <1156886315.29858.78.camel@xxxxxxxxxxxxxxxxxxxxx>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
User-agent: Thunderbird (X11/20060808)
Hollis Blanchard wrote:
On Tue, 2006-08-29 at 22:06 +0100, Ian Campbell wrote:
On Tue, 2006-08-29 at 15:24 -0500, Hollis Blanchard wrote:
Hi Ian, I needed the following patch to avoid lots of these warnings:
        elf.c:238: warning: pointer of type `void *' used in arithmetic

Fix void* arithmetic warnings.
Signed-off-by: Hollis Blanchard <hollisb@xxxxxxxxxx>
Looks like PPC is the only arch using -Wpointer-arith, is there a reason
for that?

Is there are reason the other architectures *aren't* using it?

We have some extra warnings enabled because they've helped us in the
past (such as -Wshadow). Given that we're just playing janitor for
everyone else's code though, I think we're about to abandon that one.

Pointer arith is quite valid on void pointers, when using gcc and most other modern compilers.

Point of fact, any Linux kernel-related code REQUIRES that void* arith be valid, and not cause warnings.

As we see from your patch, all a cast to char* does is complicate the code, for zero gain.


Xen-devel mailing list