OpenIndiana illumos-gate provides new debug.illumos variant. This allows DEBUG kernel modules to be installed that match the non-DEBUG kernel modules’ functionality. This variant defaults to false.

To use it:

[email protected]:/root# beadm list
BE            Active Mountpoint     Space Policy Created
openindiana   -      -              9.50M static 2016-06-16 11:37
openindiana-1 -      -              1.10G static 2016-08-31 15:58
openindiana-2 NR     /              5.20G static 2016-08-31 16:03
[email protected]:/root# pkg change-variant --be-name DEBUG debug.illumos=true
            Packages to change: 201
     Variants/Facets to change:   1
       Create boot environment: Yes
Create backup boot environment:  No

DOWNLOAD                                PKGS         FILES    XFER (MB)   SPEED
Completed                            201/201     3028/3028  101.4/101.4  2.6M/s

PHASE                                          ITEMS
Updating modified actions                  3348/3348
Updating package state database                 Done 
Updating package cache                           0/0 
Updating image state                            Done 
Creating fast lookup database                   Done 

A clone of openindiana-2 exists and has been updated and activated.
On the next boot the Boot Environment DEBUG will be
mounted on '/'.  Reboot when ready to switch to this updated BE.

[email protected]:/root# beadm list
BE            Active Mountpoint     Space Policy Created
openindiana   -      -              9.50M static 2016-06-16 11:37
openindiana-1 -      -              1.10G static 2016-08-31 15:58
openindiana-2 N      /              23.0K static 2016-08-31 16:03
DEBUG         R      -              6.55G static 2016-08-31 16:06

Debug variant is helpful for systems that are encountering problem that require full kernel debugging and troubleshooting is needed. Please, keep in mind that a DEBUG kernel will be noticeably slower.