diff options
Diffstat (limited to 'sys/compat/linuxkpi/common/include/linux/kdev_t.h')
| -rw-r--r-- | sys/compat/linuxkpi/common/include/linux/kdev_t.h | 15 |
1 files changed, 15 insertions, 0 deletions
diff --git a/sys/compat/linuxkpi/common/include/linux/kdev_t.h b/sys/compat/linuxkpi/common/include/linux/kdev_t.h index 988dd771254a..964b7078e7f5 100644 --- a/sys/compat/linuxkpi/common/include/linux/kdev_t.h +++ b/sys/compat/linuxkpi/common/include/linux/kdev_t.h @@ -31,6 +31,21 @@ #include <sys/types.h> +/* + * The encoding of major/minor on FreeBSD is complex to take into account the + * compatibility with 16-bit dev_t (see <sys/types.h>). It is not possible to + * use a simple shift and thus, we can't have a proper definition of + * `MINORBITS`. + * + * At the time this is added to linuxkpi, this is used by the DRM generic code + * as the upper limit to allocate an ID using an xarray. It is not used to + * decode a minor, therefore any arbitrary value here is fine in this context. + * + * On Linux, the value is set to 20. Because of the above, we reuse this value, + * even so it does not correspond to the actual minor encoding on FreeBSD. + */ +#define MINORBITS 20 + #define MAJOR(dev) major(dev) #define MINOR(dev) minor(dev) #define MKDEV(ma, mi) makedev(ma, mi) |