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For debugging purposes, set the lockmode attribute to 4. Follow these steps
to set the lockmode attribute to 4:
1. Create a stanza-formatted file named, for example, generic.stanza
that appears as follows:
generic:
lockmode=4
The contents of this file indicate that you are modifying the lockmode
attribute of the generic subsystem.
2. Add the new definition of lockmode to the /etc/sysconfigtab
database:
#
sysconfigdb -a -f generic.stanza generic
3. Reboot your system.
Some of the debugging features provided with lockmode set to 4 are as
follows:
• Automatic lock hierarchy checking and minimum spl checking when
any kernel lock is acquired (assuming a lockinfo structure exists
for the lock class in question). This checking helps you find potential
deadlock situations.
• Lock initialization checking.
• Additional debug information maintenance, including information about
simple and complex locks.
For simple locks, the system records an array of the last 32 simple locks
which were acquired on the system (slock_debug). The system creates
a slock_debug array for each CPU in the system.
For complex locks, the system records the locks owned by each thread in
the thread structure (up to eight complex locks).
To get a list of the complex locks a thread is holding use these commands:
# dbx -k /vmunix
(dbx) print thread->lock_addr
{
[0] 0xe4000002a67e0030
[1] 0xc3e0005b47ff0411
[2] 0xb67e0030a6130048
[3] 0xa67e0030d34254e5
[4] 0x279f0200481e1617
[5] 0x4ae33738a7730040
[6] 0x477c0101471c0019
[7] 0xb453004047210402
}
(dbx) print slock_debug
{
Kernel Debugging Utilities 2–11