The following is a demonstration of the /dev/bnull device.

Both /dev/null (the character device) and /dev/bnull (the block device version)
behave in the same way,

   # find /etc > /dev/null
   # find /etc > /dev/bnull
   #


But they are different, /dev/bnull is a block special device,

   # ls -lL /dev/null
   crw-rw-rw-   1 root     sys       13,  2 Nov 27 15:00 /dev/null
   #
   # ls -lL /dev/bnull
   brw-rw-rw-   1 root     sys      181,  0 Nov 27 15:00 /dev/bnull
   #


The following shows that the bnull driver is loaded, and the destinations of
the symlinks,

   # modinfo | grep bnull
   185 f976b948    774 181   1  bnull (bnull driver v0.70)
   #
   # ls -l /dev/null
   lrwxrwxrwx   1 root     other         27 Apr 17  2005 /dev/null -> ../devices/pseudo/mm@0:null
   #
   # ls -l /dev/bnull
   lrwxrwxrwx   1 root     root          27 Nov 27 04:04 /dev/bnull -> ../devices/pseudo/bnull@0:c
   #