linux/lib
Bernhard Kaindl f212ec4b7b x86: early boot debugging via FireWire (ohci1394_dma=early)
This patch adds a new configuration option, which adds support for a new
early_param which gets checked in arch/x86/kernel/setup_{32,64}.c:setup_arch()
to decide wether OHCI-1394 FireWire controllers should be initialized and
enabled for physical DMA access to allow remote debugging of early problems
like issues ACPI or other subsystems which are executed very early.

If the config option is not enabled, no code is changed, and if the boot
paramenter is not given, no new code is executed, and independent of that,
all new code is freed after boot, so the config option can be even enabled
in standard, non-debug kernels.

With specialized tools, it is then possible to get debugging information
from machines which have no serial ports (notebooks) such as the printk
buffer contents, or any data which can be referenced from global pointers,
if it is stored below the 4GB limit and even memory dumps of of the physical
RAM region below the 4GB limit can be taken without any cooperation from the
CPU of the host, so the machine can be crashed early, it does not matter.

In the extreme, even kernel debuggers can be accessed in this way. I wrote
a small kgdb module and an accompanying gdb stub for FireWire which allows
to gdb to talk to kgdb using remote remory reads and writes over FireWire.

An version of the gdb stub fore FireWire is able to read all global data
from a system which is running a a normal kernel without any kernel debugger,
without any interruption or support of the system's CPU. That way, e.g. the
task struct and so on can be read and even manipulated when the physical DMA
access is granted.

A HOWTO is included in this patch, in Documentation/debugging-via-ohci1394.txt
and I've put a copy online at
ftp://ftp.suse.de/private/bk/firewire/docs/debugging-via-ohci1394.txt

It also has links to all the tools which are available to make use of it
another copy of it is online at:
ftp://ftp.suse.de/private/bk/firewire/kernel/ohci1394_dma_early-v2.diff

Signed-Off-By: Bernhard Kaindl <bk@suse.de>
Tested-By: Thomas Renninger <trenn@suse.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-01-30 13:34:11 +01:00
..
lzo
reed_solomon
zlib_deflate
zlib_inflate
.gitignore
argv_split.c
audit.c
bitmap.c
bitrev.c
bug.c
bust_spinlocks.c
check_signature.c
cmdline.c
cpumask.c
crc7.c
crc16.c
crc32.c
crc32defs.h
crc-ccitt.c
crc-itu-t.c
ctype.c
debug_locks.c
dec_and_lock.c
devres.c
div64.c
dump_stack.c
extable.c
fault-inject.c
find_next_bit.c ext4: Add ext4_find_next_bit() 2008-01-28 23:58:27 -05:00
gen_crc32table.c
genalloc.c
halfmd4.c
hexdump.c
hweight.c
idr.c
inflate.c
int_sqrt.c
iomap_copy.c
iomap.c
ioremap.c
irq_regs.c
kasprintf.c
Kconfig
Kconfig.debug x86: early boot debugging via FireWire (ohci1394_dma=early) 2008-01-30 13:34:11 +01:00
kernel_lock.c sched: remove the !PREEMPT_BKL code 2008-01-25 21:08:33 +01:00
klist.c
kobject_uevent.c Kobject: fix coding style issues in kobject c files 2008-01-24 21:59:04 -08:00
kobject.c Kobject: fix coding style issues in kobject c files 2008-01-24 21:59:04 -08:00
kref.c kref: add kref_set() 2008-01-24 20:40:05 -08:00
libcrc32c.c
list_debug.c
locking-selftest-hardirq.h
locking-selftest-mutex.h
locking-selftest-rlock-hardirq.h
locking-selftest-rlock-softirq.h
locking-selftest-rlock.h
locking-selftest-rsem.h
locking-selftest-softirq.h
locking-selftest-spin-hardirq.h
locking-selftest-spin-softirq.h
locking-selftest-spin.h
locking-selftest-wlock-hardirq.h
locking-selftest-wlock-softirq.h
locking-selftest-wlock.h
locking-selftest-wsem.h
locking-selftest.c
Makefile [LIB]: Introduce struct pcounter 2008-01-28 14:54:39 -08:00
parser.c
pcounter.c [LIB] pcounter : unline too big functions 2008-01-28 15:00:35 -08:00
percpu_counter.c
plist.c
prio_heap.c
prio_tree.c
proportions.c lib: proportion: fix underflow in prop_norm_percpu() 2007-12-23 12:54:37 -08:00
radix-tree.c
random32.c
rbtree.c
reciprocal_div.c
rwsem-spinlock.c
rwsem.c x86: fix UML and -regparm=3 2008-01-30 13:33:00 +01:00
scatterlist.c SG: work with the SCSI fixed maximum allocations. 2008-01-28 10:54:49 +01:00
semaphore-sleepers.c
sha1.c
smp_processor_id.c
sort.c
spinlock_debug.c
string.c
swiotlb.c
textsearch.c [TEXTSEARCH]: Do not allow zero length patterns in the textsearch infrastructure 2007-12-01 00:03:52 +11:00
ts_bm.c
ts_fsm.c
ts_kmp.c
vsprintf.c