Wednesday, November 13, 2019

Compiling cloudflared for armv6

I have a Raspberry Pi 1 running pi-hole for ads filtering.  Recently I tried to configure it to use Cloudflare DNS-over-https but it isn't stable.  Not to mention that the latest "official" release of cloudflared is broken for Raspberry Pi.  So here are the steps to compile it on Raspberry Pi (Note that the build process will take 30+ minutes on RPi.  So you may want to cross-compile it on a PC instead.  Just change the env variable CGO_ENABLED to 0 in the build script.  It only takes a few seconds to compile on my Ryzen 2200G.  Compiling it on RPi is just for fun).


We need golang 1.12 or later to compile cloudflared.  But the official go version on Raspbian is 1.7.  Use this to download golang 1.12.  Extract the content and take note of the path.


Also, the build process needs more than 1GB of memory.  You may want to create a temporary swap file:

sudo fallocate -l 1G swapfile

sudo dd if=/dev/zero of=swapfile bs=1M count=1024
sudo chmod 600 swapfile
sudo mkswap swapfile
sudo swapon swapfile

After building cloudflared, you can use "swapoff" to remove the temporary swap space and then delete the physical file.


Here is the script to compile the cloudflared binary.  Save and run it under a working folder.  Edit the definition of the first two variables to point to the golang version you are using and the cloudflared version to compile.  If you are corss-compiling, change the "CC" environment to the cross compiler.

set -e

# custom install version of go >= 1.12
# which version to build

export GOPATH=$(pwd)
export GOOS=linux
export GOARCH=arm
export GOARM=6
export CGO_ENABLED=1
export CC=gcc

go get -v
cd src/
git checkout tags/${CLOUDFLARED_VERSION}
cd ../../../../

go build -v "-ldflags=-X 'main.Version=${CLOUDFLARED_VERSION}' -X 'main.BuildTime=${CLOUDFLARED_BUILDTIME}'"


Follow the instructions on pi-hole web site on how to configure pi-hole to use DNS-over-https

Saturday, May 4, 2019

Building Visual Studio Code on Jetson Nano

Here are the steps for building Visual Studio Code on Nvidia Jetson Nano.

Install nodejs

Visual Studio Code needs node version between 8 and 10. To install node 10 and yarn:

curl -sL | sudo -E bash -

sudo apt-get install -y nodejs

curl -sL | sudo apt-key add -

echo "deb stable main" | sudo tee /etc/apt/sources.list.d/yarn.list

sudo apt-get update && sudo apt-get install yarn

Install libraries 

We also need some libraries:

sudo apt-get install libx11-dev libxkbfile-dev libsecret-1-dev 

Clone and build Visual Studio Code

In a working directory, clone the source code and build.

git clone

cd vscode

scripts/ install

Edit 2019-06-15: To enable extensions, edit the product.json file and add the following:

"extensionsGallery": {
  "serviceUrl": "",
  "cacheUrl": "",
  "itemUrl": ""

To run Visual Studio Code:


Friday, May 3, 2019

ROCm OpenCL with openSUSE Tumbleweed

EDIT 2022:

Follow the latest doc instead:

EDIT 20200622:
With ROCm 3.5, the easiest way is to use zypper.

- Add repository:
sudo zypper addrepo --no-gpgcheck rocm
sudo zypper ref

- Install packages:
sudo zypper in rocm-opencl3.5.0 hsa-ext-rocr-dev3.5.0

- Update lib path (if necessary). ROCm 3.5 is installed under "/opt/rocm-3.5.x". Create a symbolic link "/opt/rocm -> /opt/rocm-3.5.1". Check the lib path in /etc/ and make sure these are listed

  - /opt/rocm/lib
  - /opt/rocm/lib64
  - /opt/rocm/hsa/lib
  - /opt/rocm/opencl/lib

If not, create a new file (e.g. rocm.conf) and add the above paths.  Then run "sudo ldconfig".

Run both "/usr/bin/clinfo" and "/opt/rocm/opencl/bin/clinfo" to check if OpenCL is working.

EDIT 20200110:
(0) As of 2020-01-05, running "clinfo" with openSUSE Tumbleeweed 20200103 and these  ROCm packages will cause null pointer dereference errors.
(0) Things are working again with Tumbleeweed 20200108.
(1) The user needs to be member of the "video" group.  Run this command to add yourself to the group "sudo usermod -a -G video $LOGNAME"
(2) The site now has RPM packages for openSUSE.  Go the to download the packages instead.  Also, no need to specify "--nodeps" when installing the packages

- - 8< - - -

With Tumbleweed running Linux kernel 5.0, it is easy to install ROCm OpenCL with upstream kernel.

- Go to and download the latest version of following packages:


(EDIT 20200126) With ROCm 3.0, you also need to install these packages (due to an issue):

- Install them without checking dependencies, assuming you already have libc etc packages installed, e.g.:

sudo rpm -ivh comgr- hsakmt-roct-1.0.9-319-g02e2b30.x86_64.rpm hsa-rocr-dev-1.1.30100.0-local-build-ecafeba1-Linux.rpm rocm-opencl-2.0.0--8f28d95ad-Linux.rpm rocm-opencl-devel-2.0.0--8f28d95ad-Linux.rpm rocm-smi-lib64- rocminfo-

- That's it! Optionally, install clinfo with zypper to check the available platforms.  Or you can just use the one installed by rocminfo (under /opt/rocm*/bin). If you have been using Mesa OpenCL, you may want to uninstall it.

Saturday, April 20, 2019

OpenCL hangs with mesa-opencl and Radeon

OpenCL applications (e.g. clinfo and gimp etc) will hang when running under openSUSE Tumbleweed. This is with Mesa-libOpenCL 19.0.1 running on Radeon Sea Islands with amdgpu driver (radeon.cik_support=0 amdgpu.cik_support=1 amdgpu.dc=1).

Seems hitting this same bug.

EDIT: Fixed in Mesa 19.0.3.

Monday, March 25, 2019

NVIDIA Jetson Nano first impression

Just received my NVIDIA Jetson Nano developer kit today.  Here are my first impressions:

- the mounting holes on the board are tiny.  M3 pole won't fit.  The package does come with a paper (!) stand though

- the board is picky on the power supply.  Tried several USB chargers and the board will shutdown during boot.  Ended up using the barrel plug.  Needed to short jumper J48 to enable power supply via the barrel plug.

- during first boot, after configuring the keyboard etc, the machine froze when trying to login.  Needed to recycle the power.

- Need to manually install Tensorflow for python3 (this should install the CUDA accelerated Tensorflow)

- When trying to install scipy with pip3  (compiling from source), the heatsink was too hot to touch and the machine eventually locked up.  Needed to cycle the power to reboot.

- the cpuinfo:

- dmesg:

- lsusb (with keyboard and mouse attached):

- first successful login:

Sunday, February 24, 2019

Windows 7 update error 0x8000FFFF

Just found that my Windows 7 box failed to install the monthly quality rollup since Sep 2018.

There are many discussions on the error code 8000FFFF.  From modifying registry to restarting services.

But in my case, it turns out that the monthly rollups depend on another package KB3177467.  Once manually install KB3177467, the latest monthly rollup can be installed successfully.

Microsoft, please learn to set up dependencies.

Sunday, January 27, 2019

Playing with Google Apps Script

Long time no post!

Here is a little piece of Javascript code that I recently wrote on a Sunday evening.  To be exact, it is a Google Apps Script.

The script processes credit card purchase notifications in my Gmail inbox and logs the data on a Google Sheet.  From there, I could further analyze my spending.

First time using Google Apps Script.  Seems quite powerful and a handy tool for automation.