[Mesa-dev] [PATCH 2/5] i965: use mmap64 for Android

[Rob Herring]

On Tue, May 23, 2017 at 5:12 PM, Ian Romanick <idr at freedesktop.org> wrote:
> On 05/23/2017 12:49 PM, Rob Herring wrote:
>> Simplify the handling of mmap for Android by using mmap64 instead. mmap64
>> may have not existed for Android when this was written, but it's been
>> around since 2013.
>>
>> Signed-off-by: Rob Herring <robh at kernel.org>
>> ---
>>  src/mesa/drivers/dri/i965/libdrm_macros.h | 17 ++---------------
>>  1 file changed, 2 insertions(+), 15 deletions(-)
>>
>> diff --git a/src/mesa/drivers/dri/i965/libdrm_macros.h b/src/mesa/drivers/dri/i965/libdrm_macros.h
>> index 8be103c5b7ac..d6f44a52f86b 100644
>> --- a/src/mesa/drivers/dri/i965/libdrm_macros.h
>> +++ b/src/mesa/drivers/dri/i965/libdrm_macros.h
>> @@ -29,26 +29,13 @@
>>  #include <sys/mman.h>
>>
>>  #if defined(ANDROID) && !defined(__LP64__)
>
> Since this is inside a !defined(__LP64__) block...
>
>> -#include <errno.h> /* for EINVAL */
>>
>> -extern void *__mmap2(void *, size_t, int, int, int, size_t);
>> -
>> -static inline void *drm_mmap(void *addr, size_t length, int prot, int flags,
>> -                             int fd, loff_t offset)
>> -{
>> -   /* offset must be aligned to 4096 (not necessarily the page size) */
>> -   if (offset & 4095) {
>> -      errno = EINVAL;
>> -      return MAP_FAILED;
>> -   }
>> -
>> -   return __mmap2(addr, length, prot, flags, fd, (size_t) (offset >> 12));
>> -}
>> +#  define drm_mmap(addr, length, prot, flags, fd, offset) \
>> +              mmap64(addr, length, prot, flags, fd, offset)
>
> ...is mmap64 actually the right thing to use?  If it is, it might be
> worth adding a comment why.  That will prevent the next person from
> wondering. :)

Yes, because on 64-bit mmap and mmap64 are the same thing. The other
way this is solved on 32-bit systems is defining _FILE_OFFSET_BITS,
but that was only added more recently in Android and won't work for
older versions.

Rob