New to the Solaris 8 release is the modular debugger, mdb(1), which is unique among
available Solaris debuggers because it is easily extensible. Mdb(1) also includes a number of desirable usability features including command-line editing, command history, built-in output pager, syntax checking, and command pipelining. This is the recommended post-mortem debugger for the kernel.

To change the value of the integer variable shmmax from 8GB to 10 GB without Reboot Server, do the following

bash> cp /etc/system /etc/system_old

bash> grep shminfo_shmmax /etc/system
set shmsys:shminfo_shmmax=8589934592

bash> mdb -k
Loading modules: [ unix krtld genunix ip usba s1394 ipc nfs ptm logindmux random ]
> shminfo_shmmax /D
shminfo_shmmax:
shminfo_shmmax: 1
> shminfo_shmmax /E
shminfo_shmmax:
shminfo_shmmax: 8589934592
> $q

At we can see the "shminfo_shmmax" use a 64 bit value, let's start to change the value

bash> mdb -kw
Loading modules: [ unix krtld genunix ip usba s1394 ipc nfs ptm logindmux random ]
> shminfo_shmmax /Z 0t10737418240
shminfo_shmmax: 0x5f5e10000             =       0x19000
> shminfo_shmmax /E
shminfo_shmmax:
shminfo_shmmax: 10737418240
> $q

After successfully, change the parameter "shminfo_shmmax" at /etc/system with same value on mdb

bash> vi /etc/system
set shmsys:shminfo_shmmax=10737418240