On AIX systems, you never need to rebuild a kernel because system parameters may be changed on a running system. The current values of AIX system parameters may be displayed with the lsattr command:
# lsattr -EHl sys0 Final option letter is a lowercase L. attribute value description user_settable keylock normal State of system keylock at boot time False maxbuf 20 Maximum pages in block I/O BUFFER CACHE True maxmbuf 2048 Maximum KB real memory allowed for MBUFSTrue maxuproc 400 Maximum # PROCESSES allowed per user True autorestart false Automatically REBOOT after a crash True iostat false Continuously maintain DISK I/O history True realmem 65536 Amount of usable physical memory (KB) False conslogin enable System Console Login False fwversion IBM,SPH01184 Firmware version,revision levels False maxpout 0 HIGH water mark pending write I/Os/file True minpout 0 LOW water mark pending write I/Os/file True fullcore false Enable full CORE dump True pre430core false Use pre-430 style CORE dump True ncargs 6 ARG/ENV list size in 4KB blocks True rtasversion 1 Open Firmware RTAS version False modelname IBM,7044-270 Machine name False systemid IBM,011000189 Hardware system identifier False boottype disk N/A False SW_dist_intr false Enable SW distribution of interrupts True cpuguard disable CPU Guard True frequency 93750000 System Bus Frequency False
The list includes parameters that can be modified and ones that can't. Being able to see, for example, the amount of physical memory present on the system and the current setting of the front panel key (keylock) can be useful and convenient. The latter item is especially useful when the CPU unit is positioned so that the physical key position not readily visible.
The chdev command may be used to change many of these parameters. For example, the following command raises the maximum number of simultaneous processes that a user may run to 500:
# chdev -l sys0 -a maxuproc=500
You can also use the smit chgsys command to modify several settings at the same time.
Table 16-2 lists the most important AIX system parameters, along with their associated attribute names.