Eric Schrock - Behind the music

Eric Schrock blogs about pseudo filesystems in Solaris.
Quote:
"When DTrace was first integrated into Solaris, it had a few hacks to get around the problem of accessing kernel module data from userland. In particular, it opened /dev/kmem in order to find the address ranges of module text and data segments, and introduced a private modctl call in order to extract CTF and symbol table information. The end result was something that mostly worked, but with a few drawbacks. Opening /dev/kmem requires all privileges or membership in group sys, so even if you give a user the dtrace_kernel privilege, they still were unable to access kernel CTF and symbol information. Direct access via modctl necessitated a complicated (and sometimes broken) dance to allow 32-bit dtrace apps to work on a 64-bit kernel."