From mboxrd@z Thu Jan  1 00:00:00 1970
From: Tim Deegan <tim@xen.org>
Subject: Re: clang compilation
Date: Fri, 16 Aug 2013 09:17:49 +0100
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To: Patrick Welche <prlw1@cam.ac.uk>
Cc: Jan Beulich <JBeulich@suse.com>, xen-devel@lists.xen.org
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At 08:17 +0100 on 16 Aug (1376641071), Patrick Welche wrote:
> On Thu, Aug 15, 2013 at 10:15:31PM +0100, Tim Deegan wrote:
> > > > I've tested with every GCC I can lay my hands on (and clang 3.0),
> > > > building x86 and ARM.
> 
> Joerg has a "clang fix" for warnings for xen/arch/x86/time.c, essentially
> mul to mull or mulq - did you see such warnings when testing with clang?
> 
> http://ftp.netbsd.org/pub/pkgsrc/current/pkgsrc/sysutils/xenkernel42/patches/patch-xen_arch_x86_time.c

We already have one of those changes upstream:
http://xenbits.xen.org/gitweb/?p=xen.git;a=commitdiff;h=59a28b5f045331641cbf0c1fc8d5d67afe328939

Jan, can that be backported as far as 4.2 as a build fix?

I'm not sure why I didn't trip over the mul in mul_frac() too, but
we can probably take that if you'd like to send a patch.

The other chunk in that file is against 32-bit code, which is gone in
4.3 and 4.4.  I guess we might take that as a fix directly against 4.2.
Jan, what do you think?

The patch-xen_include_xen_lib.h in the same directory looks OK to me too
- is that also a clang fix?

The $(EXTRA_CFLAGS) runes I'm less sure of; I know people have strong
feelings about the Right Way to do that.  You seem to be using it to
pass clang-specific options -- it might be better to build with
'clang=y' and add any more warning suppressions in Config.mk where
CFLAGS-$(clang) is set.

Cheers,

Tim.