Here's the first patch that introduces the context:
+choice
+ prompt "Method for KGDB communication"
+ depends on KGDB
+ default KGDB_ONLY_MODULES
+ help
+ There are a number of different ways in which you can communicate
+ with KGDB. The most common is via serial, with the 8250 driver
+ (should your hardware have an 8250, or ns1655x style uart).
+ Another option is to use the NETPOLL framework and UDP, should
+ your ethernet card support this. Other options may exist.
+ You can elect to have one core I/O driver that is built into the
+ kernel for debugging as the kernel is booting, or using only
+ kernel modules.
+
Here's the hunk that modifies it:
@@ -193,7 +193,7 @@ config KGDB_CONSOLE
choice
prompt "Method for KGDB communication"
depends on KGDB
- default KGDB_ONLY_MODULES
+ default KGDB_8250_NOMODULE
default KGDB_MPSC if SERIAL_MPSC
help
There are a number of different ways in which you can communicate
Note the second 'default' line.