On Tue, May 16, 2017 at 3:28 PM, Kirspel, Kevin <kevin-kirs...@idexx.com> wrote: > I would like to expand support for MAP_SHARED in mmap(). I would like to > run a few ideas by the group to see which direction to go. I really only > need to expand MAP_SHARED support for some LIBBSD drivers that I want to > create. There are two approaches I can take. > > > > The first approach is to just add a mmap handler function in “struct > _rtems_filesystem_file_handlers_r”. The mmap() restrictions on MAP_SHARED > would be removed. The mmap handler for all RTEMS file systems (except SHM) > would get the default mmap handler (return EINVAL). SHM would get a handler > similar to the one found in mmap.c. In RTEMS-LIBBSD, the RTEMS character > device handler (devfs_devs.c) would be free to pass the mmap request on to > FREEBSD drivers. > This would be good. I wanted to do a mmap handler in the file table but did not get to it.
I don't quite see how this expands support for MAP_SHARED, but it should improve the engineering :) > > > The second approach includes the first approach but adds support for RTEMS > device drivers. We would need to add a mmap handler to > “rtems_driver_address_table”. The “IMFS_device_handlers” would add a mmap > handler to device_mmap(). We would need a new rtems_deviceio_mmap() > function to call the drivers mmap handler. I don’t think any BSPs will be > affected because the mmap handler of “rtems_driver_address_table” should > initialize to NULL. Any BSP would them be free to add a handler to process > mmap calls. > This makes sense at a glance. Unfortunately, I can't put any deep thought on this. It would be good to get one more set of eyes+brain on it. > > > Any opposition to the two approaches? If not, which one would you prefer? > > > > Kevin Kirspel > > Electrical Engineer - Sr. Staff > > Idexx Roswell > > 235 Hembree Park Drive > > Roswell GA 30076 > > Tel: (770)-510-4444 ext. 81642 > > Direct: (770)-688-1642 > > Fax: (770)-510-4445 > > > > > _______________________________________________ > devel mailing list > devel@rtems.org > http://lists.rtems.org/mailman/listinfo/devel _______________________________________________ devel mailing list devel@rtems.org http://lists.rtems.org/mailman/listinfo/devel
