Re: [Qemu-devel] [PATCH v14 1/2] util/mmap-alloc: support MAP_SYNC in qemu_ram_mmap()

[Wei Yang]

On Tue, Apr 23, 2019 at 10:25:18AM +0100, Stefan Hajnoczi wrote:
[...]
>> +#ifdef CONFIG_LINUX
>> +#include <linux/mman.h>
>> +#else  /* !CONFIG_LINUX */
>> +#define MAP_SYNC              0x0
>> +#define MAP_SHARED_VALIDATE   0x0
>> +#endif /* CONFIG_LINUX */
>
>MAP_SHARED_VALIDATE is is from 2017:
>
>  commit 1c9725974074a047f6080eecc62c50a8e840d050
>  Author: Dan Williams <address@hidden>
>  Date:   Wed Nov 1 16:36:30 2017 +0100
>
>    mm: introduce MAP_SHARED_VALIDATE, a mechanism to safely define new mmap 
> flags
>
>This code fails to compile on Linux hosts with pre-4.15 headers.
>

Ok, qemu build will fail on pre-4.15 linux.

>Instead you could use the following (even on Linux!):
>
>  #ifndef MAP_SYNC
>  #define MAP_SYNC 0
>  #endif
>  #ifndef MAP_SHARED_VALIDATE
>  #define MAP_SHARED_VALIDATE 0
>  #endif
>
>Either way:

You mean replace the above code to:

#ifdef CONFIG_LINUX
#include <linux/mman.h>
#endif /* CONFIG_LINUX */

#ifndef MAP_SYNC
#define MAP_SYNC 0
#endif
#ifndef MAP_SHARED_VALIDATE
#define MAP_SHARED_VALIDATE 0
#endif

>
>Reviewed-by: Stefan Hajnoczi <address@hidden>



-- 
Wei Yang
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