Trying to compile the latest Zabbix 3.4 from Subversion initially failed with the following error:

$ ./configure --enable-server --enable-agent --with-mysql
...
checking for libevent support... no
configure: error: Unable to use libevent (libevent check failed)

Apparently, libevent is required, but it is unclear why. The requirements page says that libevent is required for "IPMI monitoring and bulk metrics", however, IPMI monitoring is not used in the case above. Bulk metrics? Not sure.

The upgrade notes page similarly says that "libevent library is required for bulk metrics and IPMI monitoring".

Discussing it with glebs.ivanovskis on IRC revealed that libevent is required for server always and for proxy with IPMI. It should probably be made more clear in the documentation.