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:

***************
*** 212,217 ****
  	  Use only kernel modules to configure KGDB I/O after the
  	  kernel is booted.
  
  config KGDB_MPSC
  	bool "KGDB on MV64x60 MPSC"
  	depends on SERIAL_MPSC
--- 212,225 ----
  	  Use only kernel modules to configure KGDB I/O after the
  	  kernel is booted.
  
+ config KGDB_8250_NOMODULE
+ 	bool "KGDB: On generic serial port (8250)"
+ 	select KGDB_8250
+ 	help
+ 	  Uses generic serial port (8250) to communicate with the host
+ 	  GDB.  This is independent of the normal (SERIAL_8250) driver
+ 	  for this chipset.
+ 
  config KGDB_MPSC
  	bool "KGDB on MV64x60 MPSC"
  	depends on SERIAL_MPSC