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xen-ppc-devel

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>
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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.

        Jeff





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