random notes by quiche@

Tracing wireless API events:

cd /sys/kernel/debug/tracing

echo 1 > events/cfg80211/enable # requires wireless-3.8 or newer

echo 1 > events/mac80211/enable # available with wireless-3.4

<do some stuff here>

cat trace

Example output

tracer: nop

entries-in-buffer/entries-written: 12/12 #P:4

_-----=> irqs-off

/ _----=> need-resched

| / _---=> hardirq/softirq

|| / _--=> preempt-depth

||| / delay

TASK-PID CPU# |||| TIMESTAMP FUNCTION

| | | |||| | |

wpa_supplicant-427 [000] ..s. 6636.389338: rdev_mgmt_frame_register: phy605, wdev(1), frame_type: 0xd0, reg: true

wpa_supplicant-427 [000] ..s. 6636.389373: rdev_return_void: phy605

wpa_supplicant-427 [000] .... 6636.389900: rdev_set_power_mgmt: phy605, netdev:mlan0(1818), enabled, timeout: -1

wpa_supplicant-427 [000] .... 6636.394420: rdev_return_int: phy605, returned: 0

wpa_supplicant-427 [000] .... 6636.453881: rdev_scan: phy605

wpa_supplicant-427 [000] .... 6636.453925: rdev_return_int: phy605, returned: 0

ksdioirqd/mmc1-5353 [003] .... 6636.609710: cfg80211_return_bss: 04:f0:21:05:4e:95, band: 0, freq: 2412

ksdioirqd/mmc1-5353 [000] .... 6640.651105: cfg80211_scan_done: aborted: false

Tracing cfg80211/mac80211 function calls:

cd /sys/kernel/debug/tracing/

echo 0 > tracing_on

echo > trace # clear any existing data

echo function_graph > current_tracer

echo funcgraph-abstime > trace_options

echo ':mod:cfg80211' > set_ftrace_filter

echo ':mod:mac80211' >> set_ftrace_filter # NOTE: two '>'s here

echo 1 > tracing_on

cat trace

Tracing general network events:

cd /sys/kernel/debug/tracing/

echo 1 > events/net/enable

<do some stuff here>

cat trace

[...]

sshd-5179 [000] ..s. 6940.442983: net_dev_queue: dev=eth0 skbaddr=ed0feb38 len=114

sshd-5179 [000] ..s. 6940.443025: net_dev_xmit: dev=eth0 skbaddr=ed0feb38 len=114 rc=0

Recording a trace:

Dumping the trace by hand (cat trace) works fine for manual work. But if you want a long-running trace, do this instead:

1. cd /sys/kernel/debug/tracing/
2. echo 0 > tracing_on
3. Configure tracing by using the commands above (e.g. echo 1 > events/net/enable)
4. cat trace_pipe | gzip -c > /var/log/trace.log.gz &
5. echo 1 > tracing_on

build

to see the compiler command-line for emerge/ebuild, add CXXFLAGS="-print-cmdline" to the

environment of emerge/ebuild.

ccache

the chromiumos build tools use ccache, with the cache located in /var/cache/distfiles/ccache.

you can inspect the cache as follows.

$ CCACHE_DIR=/var/cache/distfiles/ccache ccache -s

cache directory /var/cache/distfiles/ccache

cache hit (direct) 1

cache hit (preprocessed) 0

cache miss 2

called for link 2

compile failed 1

files in cache 6

cache size 16.8 Mbytes

max cache size 1.0 Gbytes

you can clear it with

$ CCACHE_DIR=/var/cache/distfiles/ccache ccache --clear

if you run ccache manually (without using the build tools), CCACHE_DIR will probably not be set.

in this case, ccache will default to ~/.ccache as the cache directory.

$ ccache --show-stats

cache directory /home/quiche/.ccache

cache hit (direct) 1

cache hit (preprocessed) 0

cache miss 1

files in cache 3

cache size 8.5 Mbytes

max cache size 1.0 Gbytes

Working with mhtml files:

Before Ubuntu Precise:

$ for x in *.mhtml; do kmhtconvert -n -f $x; done

$ for x in */index.html; do w3m -dump $x > $(dirname $x).txt; done

With Ubuntu Precise:

$ for x in *.mhtml; do mu extract --save-all $x; done

Listing branch names:

in an existing checkout

$ git branch -a

Checking out a branch: see Working on a Branch

Enabling verbose logging for Chrome:

mount / -oremount,rw

echo "vmodule=network_event_log=1" >> /etc/chrome_dev.conf

restart ui

Monitoring cellular activation:

enable verbose logging for Chrome (see above)

ff_debug +cellular+dbus+modem+portal+service

ff_debug --level -5

tail -F /var/log/chrome/chrome | logger -t chrome-main &

tail -F /var/log/ui/ui.LATEST | logger -t chrome-ui &

tail -F /home/chronos/user/log/chrome | logger -t chrome-user &

dbus-monitor --system | logger -t dbus-monitor &

Resetting modem:

(see also http://support.verizonwireless.com/clc/devices/knowledge_base.html?id=38519)

1. Network Options -> Verizon Wireless -> View Account -> Account Overview -> log in -> cancel account
2. crosh> modem factory-reset 000000 y

make sure to do these steps in order.

Monitor mode packet capture (requires another chromebook, with a dev image):

• on connected chromebook: Ctrl-Alt-t to open crosh crosh> network_diag --wifi ctrl-m to open file manager open most recent “network_diagnostics” file search for “BSS … associated” remember “freq” for next step look for “secondary channel offset” and “STA channel width” under “HT operation” if “STA channel width” is 20, use HT20 in next step if “STA channel width” is 40, and “secondary channel offset” is “above”, use "above" in next step if “STA channel width” is 40, and “secondary channel offset” is “below”, use "below" in next step otherwise, omit HT parameter in next step

• on capture chromebook: disable wifi using UI crosh> packet_capture --frequency <freq> --ht-location <above|below>

Monitoring D-Bus signals:

$ sudo gdbus monitor --system --dest fi.w1.wpa_supplicant1 | logger -t supplicant-dbus &

Monitoring D-Bus calls:

By default, you can only monitor D-Bus signals (broadcast messages from one process to the who system)

• To enable monitoring of method calls, run ./mod_test_image_for_dbusspy.sh -i ../build/images/${BOARD}/latest/chromiumos_test_image.bin
• dbus calls will be logged in /var/log/dbusspy.log

OOBE:

How to force OOBE.