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Date: Tue, 15 Nov 2016 20:44:17 +0800
From: Fam Zheng <famz@redhat.com>
Message-ID: <20161115124417.GC9226@lemon>
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Subject: Re: [Qemu-devel] [PATCH v6 1/2] block/vxhs.c: Add support for a new
 block device type called "vxhs"
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To: Stefan Hajnoczi <stefanha@gmail.com>, Peter Maydell <peter.maydell@linaro.org>
Cc: Eric Blake <eblake@redhat.com>, kwolf@redhat.com, Venkatesha.Mg@veritas.com, ashish.mittal@veritas.com, jcody@redhat.com, qemu-devel@nongnu.org, Rakesh.Ranjan@veritas.com, armbru@redhat.com, Ketan.Nilangekar@veritas.com, Abhijit.Dey@veritas.com, pbonzini@redhat.com, Buddhi.Madhav@veritas.com, Ashish Mittal <ashmit602@gmail.com>

On Tue, 11/15 10:18, Stefan Hajnoczi wrote:
> Fam, Markus: Unfortunately neither the clean-includes script nor its
> patch series cover letter explains *why* osdep.h should be included
> before system headers.

I don't know Peter's exact intention either, but AFAICT it is about the few
quirks in osdep.h:


/* Older versions of C++ don't get definitions of various macros from
 * stdlib.h unless we define these macros before first inclusion of
 * that system header.
 */
#ifndef __STDC_CONSTANT_MACROS
#define __STDC_CONSTANT_MACROS
#endif
#ifndef __STDC_LIMIT_MACROS
#define __STDC_LIMIT_MACROS
#endif
#ifndef __STDC_FORMAT_MACROS
#define __STDC_FORMAT_MACROS
#endif

/* The following block of code temporarily renames the daemon() function so the
 * compiler does not see the warning associated with it in stdlib.h on OSX
 */
#ifdef __APPLE__
#define daemon qemu_fake_daemon_function
#include <stdlib.h>
#undef daemon
extern int daemon(int, int);
#endif

<...>


/* Mac OSX has a <stdint.h> bug that incorrectly defines SIZE_MAX with
 * the wrong type. Our replacement isn't usable in preprocessor
 * expressions, but it is sufficient for our needs. */
#if defined(HAVE_BROKEN_SIZE_MAX) && HAVE_BROKEN_SIZE_MAX
#undef SIZE_MAX
#define SIZE_MAX ((size_t)-1)
#endif