Update the kgdb docs to reflect the new directory structure and API.

Merge in the kdb shell information.

[Randy Dunlap <rdunlap@xenotime.net>: grammatical corrections]

CC: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>

These are the minimum changes to the kgdb core in order to enable an
API to connect a new front end (kdb) to the debug core.

This patch introduces the dbg_kdb_mode variable controls where the
user level I/O is routed.  It will be routed to the gdbstub (kgdb) or
to the kdb front end which is a simple shell available over the kgdboc
connection.

You can switch back and forth between kdb or the gdb stub mode of
operation dynamically.  From gdb stub mode you can blindly type
"$3#33", or from the kdb mode you can enter "kgdb" to switch to the
gdb stub.

The logic in the debug core depends on kdb to look for the typical gdb
connection sequences and return immediately with KGDB_PASS_EVENT if a
gdb serial command sequence is detected.  That should allow a
reasonably seamless transition between kdb -> gdb without leaving the
kernel exception state.  The two gdb serial queries that kdb is
responsible for detecting are the "?" and "qSupported" packets.

CC: Ingo Molnar <mingo@elte.hu>
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>
Acked-by: NMartin Hicks <mort@sgi.com>

Split the former kernel/kgdb.c into debug_core.c which contains the
kernel debugger exception logic and to the gdbstub.c which contains
the logic for allowing gdb to talk to the debug core.

This also created a private include file called debug_core.h which
contains all the definitions to glue the debug_core to any other
debugger connections.

CC: Ingo Molnar <mingo@elte.hu>
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>

linux-next-20081022//include/linux/kgdb.h:308): duplicate section name 'Description'

and fix typos in that file's kernel-doc comments.
Signed-off-by: NRandy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>

Noticed by sparse:
arch/x86/kernel/kgdb.c:556:15: warning: symbol 'kgdb_arch_pc' was not declared. Should it be static?
kernel/kgdb.c:149:8: warning: symbol 'kgdb_do_roundup' was not declared. Should it be static?
kernel/kgdb.c:193:22: warning: symbol 'kgdb_arch_pc' was not declared. Should it be static?
kernel/kgdb.c:712:5: warning: symbol 'remove_all_break' was not declared. Should it be static?

Related to kgdb_hex2long:
arch/x86/kernel/kgdb.c:371:28: warning: incorrect type in argument 2 (different signedness)
arch/x86/kernel/kgdb.c:371:28:    expected long *long_val
arch/x86/kernel/kgdb.c:371:28:    got unsigned long *<noident>
kernel/kgdb.c:469:27: warning: incorrect type in argument 2 (different signedness)
kernel/kgdb.c:469:27:    expected long *long_val
kernel/kgdb.c:469:27:    got unsigned long *<noident>
kernel/kgdb.c:470:27: warning: incorrect type in argument 2 (different signedness)
kernel/kgdb.c:470:27:    expected long *long_val
kernel/kgdb.c:470:27:    got unsigned long *<noident>
kernel/kgdb.c:894:27: warning: incorrect type in argument 2 (different signedness)
kernel/kgdb.c:894:27:    expected long *long_val
kernel/kgdb.c:894:27:    got unsigned long *<noident>
kernel/kgdb.c:895:27: warning: incorrect type in argument 2 (different signedness)
kernel/kgdb.c:895:27:    expected long *long_val
kernel/kgdb.c:895:27:    got unsigned long *<noident>
kernel/kgdb.c:1127:28: warning: incorrect type in argument 2 (different signedness)
kernel/kgdb.c:1127:28:    expected long *long_val
kernel/kgdb.c:1127:28:    got unsigned long *<noident>
kernel/kgdb.c:1132:25: warning: incorrect type in argument 2 (different signedness)
kernel/kgdb.c:1132:25:    expected long *long_val
kernel/kgdb.c:1132:25:    got unsigned long *<noident>
Signed-off-by: NHarvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>

Add in the kgdb documentation for kgdb.
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

kgdb core code. Handles the protocol and the arch details.

[ mingo@elte.hu: heavily modified, simplified and cleaned up. ]
[ xemul@openvz.org: use find_task_by_pid_ns ]
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NJan Kiszka <jan.kiszka@web.de>
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>