While debugging, it’s invaluable to be able to trace functions in the Linux
kernel. There are several tools for that task: perf, ftrace (with helper tool
like trace-cmd), bpftrace, etc.
For my own debug of kernel internals and in the last few years to debug the
i915 module for Intel graphics, I usually use tracepoints or dynamic
tracepoints (with perf probe) as the trigger for something I want to trace.
One question I get some times is “how do I trace the initial probe of a
kernel module?”. At that time you (usually) don’t yet have the module …
I’m doing some experiments to make the remote controller of Parrot’s Disco
drone (SkyController 2) to work with ArduPilot. I will talk more about this in
another post. This one is basically about a nifty tool I’ve found that I didn’t
know existed: evemu. I always used
evtest to debug the input system in Linux.
SkyController 2 runs Linux and exposes all the sticks and buttons as an evdev
device. I developed a tool to serve as a general-purpose software to be used in
this kind of device: dema-rc. Ultimate
goal is to have a software …
Very often I’m in the middle of an interactive rebase and while editing a
commit I remember I should have changed a commit that I initially didn’t mark
on the rebase todo. If you tried to git-rebase again you would notice it’s
not possible due to git’s bookkeeping of the current rebase.
In the past what I usually did was to either 1) Continue the rebase and then
rebase again to fix the previous commit or 2) Create a fixup commit with
git commit --fixup and then rebase again with --auto-squash.
Generating a new rootfs from scratch in order to test changes to early
parts of the software stack or just to have a pristine environment is
something I needed several times in the past.
Since I use Archlinux in my desktop something that I like is to have a
similar environment in the target test rootfs. I decided to re-use and
improve a script from Kay Sievers to create an installer that can be
booted as a VM, as a container or in bare metal:
arch-installer.sh.
Originally it was a script to bootstrap a Fedora image and I think …
An alternative headline is: “how to show your wife how much you love
her, the geek way”.
From 17 to 22 of September I was in New Orleans participating in the
discussions of the Linux Plumbers Conference, which has already turned
into one of my favorite conferences. Lots of fun, talking to great
people and good discussions about systemd, containers, cgroups, kernel
modules, etc. However as the headline indicates this blog post is not to
talk about the conference but rather about a toy the Intel booth was
giving out: a fan with 7 leds in its propeller. See below …