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From: | Christian Ehrhardt |
Subject: | [Qemu-devel] Re: [kvm-ppc-devel] The default for char Literals differ in signedness between platforms causing us a lot of warnings |
Date: | Wed, 16 Jan 2008 13:29:39 +0100 |
User-agent: | Thunderbird 1.5.0.12 (X11/20071018) |
Hi, the following discussion is from kvm-ppc-devel, but it is actually an qemu discussion so I move th topic to qemu-devel. The original thread is cited in the mail below, in short the issue is the following: Newer gcc versions generate warnings about implicit casts between different signed pointers. That hits a lot of qemu code at least what I saw it compiling for ppc or x86. So my question is, is there already a preferred qemu approach to get rid of these warnings either the -Wno-pointer-sign solution like in the kernel or something else (I did not find anything like that in the latest cvs snapshot or on this list)? --- thread from kvm-ppc-devel --- Jimi Xenidis wrote:
On Jan 11, 2008, at 10:04 AM, Hollis Blanchard wrote:On Fri, 2008-01-11 at 14:14 +0100, Christian Ehrhardt wrote:Hi, maybe its an issue of my build environment only, but when I compile kvm-userspace for our platform I see a lot of warnings like that in the qemu code: warning: pointer targets in passing argument 3 of 'PPC_NVRAM_set_params' differ in signedness The reason is that some code defines function prototypes and variables with the type "const unsigned char*" and then assigns a literal like "PPC" to it. But per default our platform seems to have "const signed char*" for literals and so we get a lot of annoying warnings. E.g. nearly every line in qemu/target-ppc/translate.c. Should we do anything to prevent these Warnings or do you even see those ?That warning only appears in recent versions of gcc. In fact I believe there are 3 different types: char *, unsigned char *, and signed char *, and implicitly casting between them generates the warnings. :([...]It's a qemu issue. If you want to fix it, you should bring it up on qemu-devel and see what they think about it.this is what: # disable pointer signed / unsigned warnings in gcc 4.0 KBUILD_CFLAGS += $(call cc-option,-Wno-pointer-sign,) In linux/Makefile is for. -JX
--GrĂ¼sse / regards, Christian Ehrhardt
IBM Linux Technology Center, Open Virtualization
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