DEV Community: Alexander Sack

plymouth.splash kernel cmdline tweaks discovered

Alexander Sack — Sat, 16 Jul 2022 21:49:00 +0000

Was just browsing through plymouth code and found the plymouth.splash= magic switch to select a plymouth theme....

https://gitlab.freedesktop.org/plymouth/plymouth/-/blob/main/src/main.c#L376

So in theory i can pass in "plymouth.splash=solar" and see a change of behaviour .... I will keep you posted how things work out...

Howto setup qemu-risv64-static magic for binfmt_misc on Ubuntu 20.04 Focal

Alexander Sack — Mon, 20 Dec 2021 11:38:16 +0000

Today, I tried to chroot into my beagle-v chroot experiment and realized that Ubuntu has not setup the needed binfmt_misc magic to run my RISC-V 64-bit Binaries without troubles... did some googling and digging in scripts and succeeded with this:

echo ':qemu-riscv64:M::\x7f\x45\x4c\x46\x02\x01\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\xf3\x00:\xff\xff\xff\xff\xff\xff\xff\x00\xff\xff\xff\xff\xff\xff\xff\xff\xfe\xff\xff\xff:/usr/bin/qemu-riscv64-static:CF

Now that it works so nice, I also added it to my /etc/binfmt.d directory so that it would automatically work after next reboot too. Haven't tested yet, will do so on next reboot (which might be many weeks away, so feel free to let me know if this does not work or what ...

echo ':qemu-riscv64:M::\x7f\x45\x4c\x46\x02\x01\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\xf3\x00:\xff\xff\xff\xff\xff\xff\xff\x00\xff\xff\xff\xff\xff\xff\xff\xff\xfe\xff\xff\xff:/usr/bin/qemu-riscv64-static:CF > /etc/binfmt.d/qemu-riscv64-static.conf

Have fun!

REMEMBER: gitlab ci runner & pipefail == ouch

Alexander Sack — Sat, 18 Dec 2021 01:02:10 +0000

Any odd failures that make no sense in gitlab-ci.yaml scripts? Maybe those are using pipes? Gotcha.

Gitlab has by default the pretty 'anal' pipefail bash mode fail, which you usually dont see even if you usually use "set -e" ...

So for instance we wanted to truncate certain files in CI to a certain bytesize and use this script pattern:

 - cat /path/to/largefile | head -c 131200 > /path/to/truncfile

Now interestingly enough we always had this command failing our CI scripts if the largefile became substantially larger than the head cut off.

Turned out that cat indeed will fail as its downstream process exits before its done catting the full largefile.

Try it yourself:

$ $ dd if=/dev/random of=/tmp/largefile bs=1M count=3
3+0 records in
3+0 records out
3145728 bytes (3,1 MB, 3,0 MiB) copied, 0,0467213 s, 67,3 MB/s

# here how it works nicely, with return code 0
$ cat /tmp/largefile | head 1024 > /tmp/truncfile
$ echo $?
0

# ... now set pipefail mode it fails ...
$ set -o pipefail
$ cat /tmp/largefile | head -c 1024 > /tmp/smallfile
$ echo $?
141

Ubuntu Focal 20.04 default scaling governor "powersave"

Alexander Sack — Wed, 28 Jul 2021 16:13:01 +0000

Just recently upgrade to Ubuntu 20.04 and was so far quite happy with a reasonable regression free experience.

But then - as inevitable as it might be - I ended up going for the real stuff: building full system from source.

This felt awkwardly slow ... and then i found that my CPU was running under powersave governor... i fixed this by explicitly going for performance ....

For that I did:

/etc/default/cpufrequtils:GOVERNOR="performance"

Any better ideas on how to get back "ondemand" type of behaviour?

Adding a docker container to Pantavisor Linux

Alexander Sack — Fri, 09 Jul 2021 10:16:43 +0000

Adding a Pantavisor Linux system, middleware or app container from docker is done using our pvr middleware tool.

If you are using Pantavisor Linux with our PVBox frontend you can simply use the pvboxctl "install" command to get this done:

Next you select "Add from docker"

And choose a name:

And finally type the "Docker Source" ref from your preferred docker registry:

And let pvr do the the rest:

Once finished you will have a chance to do some final edits to you app and commit it:

===============================
Pantabox Interactive Edit Shell
===============================

We have provisioned the following files
for the parts you have selected to edit:


You can now edit part \'mynewapp\' and change
them to your liking.

Remember to pvr commit any changes you might
want to apply to your system.

When done, you can:
1. apply committed changes: exit 0 (or Ctrl-D)
2. discard your changes: exit 1

For help visit: https://pantavisor.io

pvctlbox::mynewapp#

Often you can just use the container using the default configuration pantavisor linux generated for you.

Once happy you would run:

pvr add .
pvr commit

and exit the interactive shell (e.g. press ctrl-D) to apply you changes and instruct pantavisor to run the new, modified system that includes your new docker container.

HowTo: Recovery Mode for NVIDIA Jetson NANO Developer Kit

Alexander Sack — Thu, 08 Jul 2021 13:36:11 +0000

Its easy, but hard to find online, hence here for myself:

Connect Pins: GND <-> FC REC
Power On

Observe how your host can see the device connected via its USB gadget as below in dmesg:



[85283.237504] usb 1-6.2: new high-speed USB device number 84 using xhci_hcd
[85283.366258] usb 1-6.2: New USB device found, idVendor=0955, idProduct=7f21, bcdDevice= 1.02
[85283.366279] usb 1-6.2: New USB device strings: Mfr=1, Product=2, SerialNumber=0
[85283.366288] usb 1-6.2: Product: APX
[85283.366294] usb 1-6.2: Manufacturer: NVIDIA Corp.

Here the jumper cable and how I connected it for Recovery Mode (check the blue one):

Best wishes!

Howto fix a "MISSING TORADEX CONFIG BLOCK"

Alexander Sack — Tue, 29 Sep 2020 11:48:50 +0000

Yes, I bricked my Tora board... not sure how, but at some point when trying to run tezi it started to complain about

   MISSING TORADEX CONFIG BLOCK

Unfortunately, Toradex documentation is not very clear and forum/stackoverflow questions are not giving a clear answer either.

Hence after some poking here how I resolved this:

Go to Uboot Prompt
run cfgblock create

Fill in the fields that you are asked to fill in. The info you can find on the label you will find on your module.

Afterwards all worked fine again for me!

Have fun!

Banana Pi R64 + MTK 7615

Alexander Sack — Mon, 07 Sep 2020 16:40:56 +0000

With Banana Pi R64 another real beauty came on our plate.

Can't wait to see this one in action ...

A Tora Tower (TT)

Alexander Sack — Thu, 03 Sep 2020 09:45:16 +0000

My Toradex Tower is almost complete... I have now everything colibri from imx6ull to imx8 bleeding edge.

A real beauty? WDYT?

alpinelinux for armel and mips anyone?

Alexander Sack — Thu, 27 Aug 2020 16:24:21 +0000

We love alpine a lot: it's lean, it's nice, apk does its job very well and is lightweight and lightning fast to use even on low spec systems....

Unfortunately, we have devices that would benefit from these alpinelinux properties in the router and CPE segment that currently cannot benefit from it's awesomeness :(.

Hence, I am looking for interested folks that would be keen to help bootstrapping and maintaining an unofficial ports repo for armel and mips (and maybe more?) architectures.

If you like the idea and want to help ping me and we can see how we can work together.

libsctp-dev with sctp.h on alpine ... where is it?

Alexander Sack — Fri, 21 Aug 2020 11:17:24 +0000

Took me more than 10 seconds to find on google, hence this note to myself thingy...

If you need libsctp-dev to build some stuff on debian distros, you probably want lksctp-tools-dev package on alpine ...

apk info -L lksctp-tools-dev
lksctp-tools-dev-1.0.18-r1 contains:
usr/include/netinet/sctp.h
usr/lib/libsctp.so
usr/lib/pkgconfig/libsctp.pc
usr/share/lksctp-tools/checksctp.c
usr/share/lksctp-tools/sctp_bind.c
usr/share/lksctp-tools/sctp_darn.c
usr/share/lksctp-tools/sctp_darn.h
usr/share/lksctp-tools/sctp_load_libs.c
usr/share/lksctp-tools/sctp_socket.c
usr/share/lksctp-tools/sctp_socket.h
usr/share/lksctp-tools/sctp_sockopt.c
usr/share/lksctp-tools/sctp_status.c
usr/share/lksctp-tools/sctp_test.c

Branding your Toradex TEZI install experience

Alexander Sack — Fri, 14 Aug 2020 10:53:58 +0000

Once you have managed to produce a nice TEZI installer image, you will have the option to do some branding:

logo: a 32x32 log shown next to your image entry in the TEZI installer view
marketing.tar: in this tarball you find folder called slides_vga. Here you can place your slideshow as a sequence of png files, e.g. A.png, B.png, ...
image.json: this one has description and name and other fields that TEZI installer will surface in human readable areas (aka brand)

Remember the png's in marketing.tar are not getting auto scaled by TEZI installer; instead you have to ensure they are sized 640x400 pixel. I used the following command on linux to do that:

# this will replace A.png with the resized version
convert slides_vga/A.png -resize 640x400\> slides_vga/A.png

Happy Branding!