preparation
------------
change /etc/locale.conf to en_US.UTF-8
run lxpolkit
remove ZE WIFI connection from NM
virsh net-destroy cockpit1
rmmod iwldvm iwlwifi (NOT killswitch)
cd ~martin/Dokumente/computer/talks/simulated-hardware
sudo -i
mkdir -p /run/udev/rules.d/
cd ~martin/Dokumente/computer/talks/simulated-hardware
start gnome-disks on another desktop
other term: journalctl --lines=0 -f
connect phone, enable MTP; verify mtp-detect
increase font size; clear

intro (2')
----------
comparison to rocket launching
for longest time: fix production with an update
getting better with CI; but one area which is particularly tricky is hardware access on the plumbing layer
udisks, upower, NetworkManager, modemmanager, rfkill, libmtp, libinput
show how to simulate various kinds of hardware for testing and interactive debugging

disks (6')
----------
simple cases: loop devices; don't feel/smell like real HD
partitions are tricky (kpartx), no fault injection, no device types, don't scale well
more powerful: scsi_debug kmod

simple: modprobe scsi_debug dev_size_mb=100
create GPT partitioning and partition in Disks, mount it
simulate pulling an USB stick or CD drive:
echo 1 > /sys/block/sdb/device/delete
→ disappears, journal says "Cleaning up mount point"
mount | grep sdb

lots of devices:
rmmod scsi_debug
modprobe scsi_debug add_host=100

CD:
rmmod scsi_debug
modprobe scsi_debug ptype=5
rmmod scsi_debug

errors: medium error in sector 0x1234
modprobe scsi_debug opts=2
dd if=/dev/zero of=/dev/sdb
rmmod scsi_debug

doc: http://sg.danny.cz/sg/sdebug26.html
example: https://github.com/storaged-project/udisks/blob/master/src/tests/integration-test

ethernet (4.5')
---------------
veth: kernel virtual net driver, symmetric pair; consider "local" end (test
with NM), and "remote" end (set up as router with known good tool, e. g.
dnsmasq)

vim veth.sh
show nm-applet: not connected to anything
nmcli g

filter out some log noise:
journalctl -f -ocat -t NetworkManager
./veth.sh

nm-applet right-click connection info
(nmcli g)

doc: man ip-link
Debian/Ubuntu autopkgtests for NetworkManager and netplan, upstream systemd networkd

wifi (5')
---------
mac80211_hwsim kmod: real wifi driver for userspace; again a symmetric connected pair
vim wifi.sh
NM blacklisting: opposite, don't interfere with router end
new thing: hostapd for wifi router stack; real thing

journalctl -f -ocat -t NetworkManager
./wifi.sh
click on nm-applet to connect

nmcli d

Debian/Ubuntu autopkgtests for NetworkManager and netplan
https://www.kernel.org/doc/Documentation/networking/mac80211_hwsim/

generic devices (5')
--------------------
block and network are rather special; most Linux devices/drivers are much simpler (char dev, read/write, ioctl)
umockdev: mock /sys, /dev, /proc, redirects to temp dir via preload lib
emulate uevents by redirecting netlink socket
C library, GI bindings, CLI tools
needs no privileges → make check

close root shell
empty by default:
umockdev-run -- ls -l /sys
API or udevadm dump like text files:

cat foo.umockdev
similar to udevadm info --export-db: name, devnode, udev props; but with sysfs attributes
umockdev-run -d foo.umockdev bash
   tree -l /sys
   cat /sys/devices/foo/mode
   ls -l /dev/foo
   ls -l $UMOCKDEV_DIR/dev/foo

   exit

examples: upower test suite (UPS, batteries), input devs (lid, touch screen)
https://github.com/martinpitt/umockdev
packages in all major distros

Device behaviour
----------------
record/replay reads/writes to device with correct timing → 3G modems
record/replay evdev ioctls → wacom tablets
record URB; gphoto, MTP

lsusb
umockdev-record /dev/bus/usb/002/020 > /tmp/sony.umockdev
less /tmp/sony.umockdev
umockdev-record -i /dev/bus/usb/002/020=/tmp/sony.ioctl mtp-detect
less /tmp/sony.ioctl

disconnect mobile

umockdev-run -d /tmp/sony.umockdev lsusb
umockdev-run -d /tmp/sony.umockdev mtp-detect
umockdev-run -d /tmp/sony.umockdev -i /dev/bus/usb/002/020=/tmp/sony.ioctl mtp-detect

Disclaimer: URB slightly broken right now; used to work with gphoto, shotwell, etc.; but URB structure apparently got more flexible now
evdev ioctls work quite nicely (Wacom or other exotic devices); supports outputting to evemu format
can record and replay (with correct timing) raw reads/writes to devices; used for testing modems (3G/4G sticks)