A routine to instantiate and start the SNMP agent thread in the default -configuration is provided in -PACKAGES/net/snmp/agent/VERSION/src/snmptask.c
It starts the snmpd thread at priority -CYGPKG_NET_THREAD_PRIORITY+1 -by default, ie. one step less important than the TCP/IP stack service -thread. -It also statically creates and uses a very large stack of around 100 -KiloBytes. -To use that convenience function, this code fragment may be copied (in -plain C).
#ifdef CYGPKG_SNMPAGENT
-{
- extern void cyg_net_snmp_init(void);
- cyg_net_snmp_init();
-
-}
-#endif |
In case you need to perform initialization, for example setting up SNMPv3 -security features, when the snmp agent starts and every time it restarts, -you can register a callback function by simply writing the global variable: -
externC void (*snmpd_reinit_function)( void ); |
The entry point to the SNMP agent is -
externC void snmpd( void (*initfunc)( void ) ); |
Note that if you call snmpd(); yourself and do -not call cyg_net_snmp_init(); then -that routine, global variable, and the default large stack will not be -used. This is the recommended way control such features from your -application; create and start the thread yourself at the appropriate -moment.
Other APIs from the snmpd module are available, -specifically: -
void SnmpdShutDown(int a); |
The parameter a is ignored. It is there because in -snmpd's “natural environment” this routine -is a UNIX signal handler.
The helper functions in the network stack for managing -DHCP -leases will call SnmpdShutDown() -when necessary, for example if network interfaces go down and/or come up -again.