dtrace discuss - Aug 2005 - Duplication in dtrace''s forceload entries in /etc/system

Hi,

   If you have a custom kernel (and therefore have duplicates of 
everything in /kernel in your custom kernel) and have noticed that when 
you try to use anonymous tracing, dtrace adds multiple copies of the 
forceload directives to /etc/system, e.g.:

* vvvv Added by DTrace
*
* The following forceload directives were added by dtrace(1M) to allow for
* tracing during boot.  If these directives are removed, the system will
* continue to function, but tracing will not occur during boot as desired.
* To remove these directives (and this block comment) automatically, run
* "dtrace -A" without additional arguments.  See the "Anonymous
Tracing"
* chapter of the Solaris Dynamic Tracing Guide for details.
*
forceload: drv/systrace
forceload: drv/sdt
forceload: drv/profile
forceload: drv/lockstat
forceload: drv/fbt
forceload: drv/fasttrap
forceload: drv/systrace
forceload: drv/sdt
forceload: drv/profile
forceload: drv/lockstat
forceload: drv/fbt
forceload: drv/fasttrap
forceload: drv/dtrace
* ^^^^ Added by DTrace


   It''s because when libdtrace searches for providers, it searches the 
system module load paths and attempts to match module names with pseudo 
drivers to locate the providers, so it will match not only for the dtrace 
providers in, say /platform/sun4u/mykernel/..., but also for the 
"originals" in /kernel/...  It''s no big whoop, as the
additional
forceloads just result in warning messages, but it was nice to find out 
where it was coming from.

   Check out:
http://cvs.opensolaris.org/source/xref/usr/src/lib/libdtrace/common/dt_open.c#757

  for the gory details.

  --S