I have a few AIX servers, and zabbix is reporting wrong uptime for the ones which have been up for a long time:

One of the machines (AIX 6.1) has 685+ days of uptime, but zabbix reports a little more than 188 days.
Another one (AIX 5.3) has 248+ days of uptime, but zabbix always reports 0.

This seems like a 32bit bug. I've recompiled the agent as a 64bit binary, and this made the problem go away.

For completeness, these where the steps I took to rebuild zabbix_agentd for 64bit:

CFLAGS='-maix64' ./configure --enable-agent

1. On AIX 6.1 edit include/config.h and add, to the top:
2. #include <sys/protosw.h>
3. Ref: https://www-304.ibm.com/support/docview.wss?uid=isg1IV01736

make ARFLAGS="-cru -X64"

strip -X64 src/zabbix_agent/zabbix_agentd