Star64_linux/Documentation
Tejun Heo e2f15f9a79 netconsole: implement extended console support
printk logbuf keeps various metadata and optional key=value dictionary for
structured messages, both of which are stripped when messages are handed
to regular console drivers.

It can be useful to have this metadata and dictionary available to
netconsole consumers.  This obviously makes logging via netconsole more
complete and the sequence number in particular is useful in environments
where messages may be lost or reordered in transit - e.g.  when netconsole
is used to collect messages in a large cluster where packets may have to
travel congested hops to reach the aggregator.  The lost and reordered
messages can easily be identified and handled accordingly using the
sequence numbers.

printk recently added extended console support which can be selected by
setting CON_EXTENDED flag.  From console driver side, not much changes.
The only difference is that the text passed to the write callback is
formatted the same way as /dev/kmsg.

This patch implements extended console support for netconsole which can be
enabled by either prepending "+" to a netconsole boot param entry or
echoing 1 to "extended" file in configfs.  When enabled, netconsole
transmits extended log messages with headers identical to /dev/kmsg
output.

There's one complication due to message fragments.  netconsole limits the
maximum message size to 1k and messages longer than that are split into
multiple fragments.  As all extended console messages should carry
matching headers and be uniquely identifiable, each extended message
fragment carries full copy of the metadata and an extra header field to
identify the specific fragment.  The optional header is of the form
"ncfrag=OFF/LEN" where OFF is the byte offset into the message body and
LEN is the total length.

To avoid unnecessarily making printk format extended messages, Extended
netconsole is registered with printk when the first extended netconsole is
configured.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: David Miller <davem@davemloft.net>
Cc: Kay Sievers <kay@vrfy.org>
Cc: Petr Mladek <pmladek@suse.cz>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-06-25 17:00:39 -07:00
..
ABI printk: implement support for extended console drivers 2015-06-25 17:00:38 -07:00
accounting
acpi
aoe
arm Doc: Change wikipedia's URL from http to https 2015-06-22 10:14:05 -06:00
arm64
auxdisplay
backlight
blackfin
block
blockdev zram: add dynamic device add/remove functionality 2015-06-25 17:00:36 -07:00
bus-devices
cdrom
cgroups
cma
connector
console
cpu-freq Documentation updates for 4.2 2015-06-24 20:01:36 -07:00
cpuidle
cris
crypto
development-process
device-mapper
devicetree Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input 2015-06-24 19:56:58 -07:00
dmaengine
DocBook Documentation updates for 4.2 2015-06-24 20:01:36 -07:00
driver-model
dvb
early-userspace
EDID
extcon
fault-injection
fb
features
filesystems Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs 2015-06-24 20:07:10 -07:00
firmware_class
fmc
frv
gpio Documentation updates for 4.2 2015-06-24 20:01:36 -07:00
hid
hwmon
i2c
ia64
ide
infiniband
input Doc: Change wikipedia's URL from http to https 2015-06-22 10:14:05 -06:00
ioctl
isdn
ja_JP
kbuild
kdump
ko_KR
laptops
leds Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input 2015-06-24 19:56:58 -07:00
locking
m68k
memory-devices
metag
mic Documentation/mic/mpssd: don't build x86 userspace when cross compiling 2015-06-22 16:05:11 -06:00
mips
misc-devices Pratyush Anand has moved 2015-06-25 17:00:38 -07:00
mmc
mn10300
mtd
namespaces
netlabel
networking netconsole: implement extended console support 2015-06-25 17:00:39 -07:00
nfc
nios2
parisc
PCI
pcmcia
phy
platform
power
powerpc
pps Doc:pps: Fix typo in pps.txt 2015-06-22 09:59:28 -06:00
prctl Documentation/prctl: don't build tsc tests when cross compiling 2015-06-22 16:05:04 -06:00
pti
ptp
rapidio
RCU Documentation updates for 4.2 2015-06-24 20:01:36 -07:00
s390
scheduler
scsi
security
serial
sh
sound
spi
sysctl watchdog: add watchdog_cpumask sysctl to assist nohz 2015-06-24 17:49:40 -07:00
target SCSI misc on 20150622 2015-06-23 15:55:44 -07:00
thermal
timers
tpm
trace
usb
vDSO Documentation/vDSO: don't build tests when cross compiling 2015-06-22 16:04:57 -06:00
video4linux
virtual
vm zswap: runtime enable/disable 2015-06-25 17:00:37 -07:00
w1
watchdog
wimax
x86 Merge branch 'x86-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2015-06-22 17:59:09 -07:00
xtensa
zh_CN Documentation updates for 4.2 2015-06-24 20:01:36 -07:00
00-INDEX
applying-patches.txt
assoc_array.txt
atomic_ops.txt
bad_memory.txt
basic_profiling.txt
bcache.txt
binfmt_misc.txt
braille-console.txt
bt8xxgpio.txt
btmrvl.txt
BUG-HUNTING
bus-virt-phys-mapping.txt
cachetlb.txt
Changes
circular-buffers.txt
clk.txt
coccinelle.txt
CodeOfConflict
CodingStyle
cpu-hotplug.txt
cpu-load.txt
cputopology.txt
crc32.txt
dcdbas.txt
debugging-modules.txt
debugging-via-ohci1394.txt Doc: Change wikipedia's URL from http to https 2015-06-22 10:14:05 -06:00
dell_rbu.txt
devices.txt
digsig.txt
DMA-API-HOWTO.txt Documentation updates for 4.2 2015-06-24 20:01:36 -07:00
DMA-API.txt
DMA-attributes.txt
dma-buf-sharing.txt
DMA-ISA-LPC.txt
dontdiff
dynamic-debug-howto.txt
edac.txt EDAC: Update Documentation/edac.txt 2015-06-24 18:17:40 +02:00
efi-stub.txt
eisa.txt
email-clients.txt
flexible-arrays.txt
futex-requeue-pi.txt
gcov.txt
gdb-kernel-debugging.txt
highuid.txt
HOWTO
hsi.txt
hw_random.txt
hwspinlock.txt
init.txt
initrd.txt
Intel-IOMMU.txt
intel_txt.txt
io-mapping.txt
io_ordering.txt
iostats.txt
IPMI.txt
IRQ-affinity.txt
IRQ-domain.txt
IRQ.txt
irqflags-tracing.txt
isapnp.txt
java.txt
kasan.txt
kernel-doc-nano-HOWTO.txt
kernel-docs.txt
kernel-parameters.txt Documentation updates for 4.2 2015-06-24 20:01:36 -07:00
kernel-per-CPU-kthreads.txt
kmemcheck.txt
kmemleak.txt Doc: Change wikipedia's URL from http to https 2015-06-22 10:14:05 -06:00
kobject.txt
kprobes.txt
kref.txt
kselftest.txt
ldm.txt
local_ops.txt
lockup-watchdogs.txt watchdog: add watchdog_cpumask sysctl to assist nohz 2015-06-24 17:49:40 -07:00
logo.gif
logo.txt
lzo.txt
magic-number.txt
mailbox.txt
Makefile
ManagementStyle
md-cluster.txt
md.txt doc:md: fix typo in md.txt. 2015-06-23 06:49:44 -06:00
media-framework.txt
memory-barriers.txt Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2015-06-22 14:54:22 -07:00
memory-hotplug.txt
module-signing.txt
mono.txt
nommu-mmap.txt
numastat.txt
oops-tracing.txt
padata.txt
parport-lowlevel.txt
parport.txt
percpu-rw-semaphore.txt
phy.txt
pi-futex.txt
pinctrl.txt
pnp.txt
preempt-locking.txt
printk-formats.txt
pwm.txt
ramoops.txt
rbtree.txt
remoteproc.txt
rfkill.txt
robust-futex-ABI.txt
robust-futexes.txt
rpmsg.txt
rtc.txt
SAK.txt
SecurityBugs
serial-console.txt
sgi-ioc4.txt
SM501.txt
smsc_ece1099.txt
sparse.txt
stable_api_nonsense.txt
stable_kernel_rules.txt
static-keys.txt
SubmitChecklist
SubmittingDrivers
SubmittingPatches
svga.txt
sysfs-rules.txt
sysrq.txt
this_cpu_ops.txt
unaligned-memory-access.txt
unicode.txt
unshare.txt
vfio.txt
VGA-softcursor.txt
vgaarbiter.txt
video-output.txt
vme_api.txt
volatile-considered-harmful.txt
workqueue.txt
xillybus.txt
xz.txt
zorro.txt