Michael Brown
6e1ce52d14
[debug] Allow debug messages to be initially disabled at runtime
Extend the DEBUG=... syntax to allow debug messages to be compiled in
but disabled by default. For example:
make bin/undionly.kpxe DEBUG=netdevice:3:1
would compile in the messages as for DEBUG=netdevice:3, but would set
the debug level mask so that only the DEBUG=netdevice:1 messages would
be displayed.
This allows for external code to selectively enable the additional
debug messages at runtime, without being overwhelmed by unwanted
initial noise. For example, a developer of a new protocol may want to
temporarily enable tracing of all packets received: this can be done
by building with DEBUG=netdevice:3:1 and using
// temporarily enable per-packet messages
DBG_ENABLE_OBJECT ( netdevice, DBGLVL_EXTRA );
...
// disable per-packet messages
DBG_DISABLE_OBJECT ( netdevice, DBGLVL_EXTRA );
Note that unlike the usual DBG_ENABLE() and DBG_DISABLE() macros,
DBG_ENABLE_OBJECT() and DBG_DISABLE_OBJECT() will not be removed via
dead code elimination if debugging is disabled in the specified
object. In particular, this means that using either of these macros
will always result in a symbol reference to the specified object.
Signed-off-by: Michael Brown <mcb30@ipxe.org>