Re: [Qemu-devel] [PATCH v6 1/2] block/vxhs.c: Add support for a new block device type called "vxhs"

[ashish mittal]

Thanks for concluding on this.

I will rearrange the qnio_api.h header accordingly as follows:

+#include "qemu/osdep.h"
+#include <qnio/qnio_api.h>   <=== after osdep.h
+#include "block/block_int.h"
+#include "qapi/qmp/qerror.h"
+#include "qapi/qmp/qdict.h"
+#include "qapi/qmp/qstring.h"
+#include "trace.h"
+#include "qemu/uri.h"
+#include "qapi/error.h"
+#include "qemu/error-report.h"  <==== remove


On Tue, Nov 15, 2016 at 11:20 AM, Stefan Hajnoczi <address@hidden> wrote:
> On Tue, Nov 15, 2016 at 11:00:16PM +0800, Fam Zheng wrote:
>> On Tue, 11/15 14:45, Stefan Hajnoczi wrote:
>> > On Tue, Nov 15, 2016 at 08:44:17PM +0800, Fam Zheng wrote:
>> > > 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
>> >
>> > This is exactly the kind of stuff we should not be doing to the libqnio
>> > header file!
>> >
>> > Those redefinitions are useful for QEMU code.  They should not be done
>> > to third-party system headers though.
>>
>> But we still want to include osdep.h before libqnio pulls in stdint.h. If we
>> don't make osdep.h the very first, that cannot be guaranteed.
>
> Thanks, that makes sense!
>
> I'll add a comment to clean-includes with this explanation of why
> osdep.h must go before system headers.
>
> Stefan