Simple program to query OS clock resolution using clock_getres(2) call. Such information can be useful if you plan to use clock_gettime(2) in your programs.

WARNING! This project is in transition from plain make(1) to cmake(1)

WARNING #2 ! Now we can even (cross)build with Google's Bazel - see sections below.

WARNING! Since cfcd454 Debian specific files (the debian/ directory) were moved from branch master to debs/master. Similarly since 0d5c1cb RPM specific files (clockres.spec and .tito/*) were moved from master branch to rpms/master. So now there are these branches:

• master - primary development branch. Only native source here (no package specific files allowed here)
• debs/master - this branch contains debian/ directory necessary to build Debian packages.
• rpms/master - this branch contains clockres.spec and .tito/ used to build RPM packages

Common setup:

• install git:

  # on RHEL/CentOS 7,8...
  sudo yum install -y git
  # on Debian
  sudo apt-get install -y git
  # on OpenSUSE 15
  sudo zypper in git-core

• clone this repository:

  mkdir -p ~/projects
  cd ~/projects
  git clone https://github.com/hpaluch-pil/clockres.git
  cd clockres/

• follow instructions below...

Tested on: Debian 10/amd64

Just install:

sudo apt-get install build-essential cmake

sudo yum install gcc make cmake

To build, run cmake wrapper script:

./rebuild_cmake_linux.sh

This also apply for armel build under Nokia's scratchbox.

However you need to download build and install cmake-3.0.2 by yourself first.

Tested on Linux Host (CentOS 5.4).

For cmake build you need to:

• download build and install cmake-3.0.2
• and then just run:

./rebuild_cmake_qnx.sh

Tested on Linux Host (Ubuntu 16.04.6 LTS). For build use:

source ~/qnx700/qnxsdp-env.sh
./rebuild_cmake_qnx.sh

Now we can build with Bazel - Google's building tool.

For openSUSE LEAP 15.3 Install these packages:

sudo zypper in git-core bazel gcc-c++ glibc-devel
sudo zypper in bazel python-devel python-xml

For Fedora 35 install these unofficial COPR packages (COPR is like SUSE's OBS - public package build service), see https://bazel.build/install/redhat

dnf install dnf-plugins-core
dnf copr enable vbatts/bazel
dnf install bazel4
dnf install git-core gcc gcc-c++ glibc-devel

For Debian 11 follow: https://bazel.build/install/ubuntu, approximately:

• install GPG key

  sudo apt-get install apt-transport-https curl gnupg
  curl -fsSLO https://bazel.build/bazel-release.pub.gpg
  gpg --dearmor bazel-release.pub.gpg 
  sudo cp bazel-release.pub.gpg.gpg /usr/share/keyrings/bazel-archive-keyring.gpg

• now create file /etc/apt/sources.list.d/bazel.list with contents:

  deb [arch=amd64 signed-by=/usr/share/keyrings/bazel-archive-keyring.gpg] https://storage.googleapis.com/bazel-apt stable jdk1.8
  

• and finally

  sudo apt-get update
  sudo apt-get install bazel
  sudo apt-get install git-core g++ libc-dev libstdc++-10-dev

Run build:

# this shows available targets
bazel query ...
# run only target
bazel build //:clockres

The resulting binary is (symlinked) can be run as:

bazel-bin/clockres

Once you are done, shutdown server (automatically run by first invocation of bazel):

bazel shutdown

Prepare Linaro toolchain (the target path is hardcoded):

cd
curl -fLO https://releases.linaro.org/components/toolchain/binaries/7.2-2017.11/aarch64-linux-gnu/gcc-linaro-7.2.1-2017.11-x86_64_aarch64-linux-gnu.tar.xz
tar xvf gcc-linaro-7.2.1-2017.11-x86_64_aarch64-linux-gnu.tar.xz
# WARNING! Symbolic link will not work - must be absolute canonical path
sudo mv gcc-linaro-7.2.1-2017.11-x86_64_aarch64-linux-gnu /opt/aarch64-linux-gnu
sudo chown root:root -R /opt/aarch64-linux-gnu/
# quick test
/opt/aarch64-linux-gnu/bin/aarch64-linux-gnu-gcc -dumpmachine
# should print: aarch64-linux-gnu

To cross-build for aarch64 using above Linaro cross-gcc in /opt/aarch64-linux-gnu/ run this command:

bazel build --config=aarch64 '//:clockres'

To verify binary architecture try:

$ readelf -h bazel-bin/clockres | fgrep 'Machine:'

  Machine:                           AArch64

Done!

Bugs:

• Bazel always builds C++ binary (even when source is *.c)
  • see bazelbuild/bazel#2954
  • you can verify it with command:

    ldd bazel-bin/clockres
    
        linux-vdso.so.1 (0x00007ffed2f91000)
        libstdc++.so.6 => /usr/lib64/libstdc++.so.6 (0x00007ff493bcb000)
        libm.so.6 => /lib64/libm.so.6 (0x00007ff493880000)
        libc.so.6 => /lib64/libc.so.6 (0x00007ff49348b000)
        /lib64/ld-linux-x86-64.so.2 (0x00007ff493fde000)
        libgcc_s.so.1 => /lib64/libgcc_s.so.1 (0x00007ff493272000)

  • notice the libstdc++.so.6 - should not be there...

Obviously can be used for self-hosted builds (but cross-builds). Look for binary clockres under ~/tmp/build/clockres-*/

WARNING! Since cfcd454 the debian/ directory was moved from master branch to debs/master. You therefore need to switch to debs/master branch before building Debian packages using:

git checkout debs/master

You can now create native Debian packages thanks to metadata under debian/ directory.

To generate just binary .deb package in parent directory, issue:

debuild -i -us -uc -b

To generate source deb-src files (useful if you plan to user pbuilder - personal builder for many Debian versions) under chroot:

debuild -i -us -uc -S

It is often desirable to have unique name of binary packages for different Debian distribution - typically in form +deb10u1 which means "for Debian 10 Update 1". Currently there is this clumsy way to do this:

# use "source" for bash or "." for dash
source /etc/os-release
dch -v "0.1+deb${VERSION_ID}u1" -D $VERSION_CODENAME "Added final distribution tag"
# and rebuild packages as usual
debuild -i -us -uc -S
# rollback modified debian/changelog
git checkout -- debian/changelog

It is experimental.

At first install required packages:

sudo apt-get install git-buildpackage pristine-tar

Then I can build Debian package using:

gbp buildpackage
# packages are build into ../build-area/

WARNING! It will not work for you so far! It requires my GPG key to sign all files.

WARNING! Since 0d5c1cb the RPM specific files were moved from master branch to rpms/master. You therefore need to switch to rpms/master branch before building RPM packages using:

git checkout rpms/master

This projects uses tool Tito

Tested versions:

• OS: CentOS 7.9.2009 (see /etc/redhat-release)
• Tito tool: 0.6.15 (from tito --version command)

To build RPM prepare your system:

• enable EPEL repository using

  sudo rpm -ivh https://dl.fedoraproject.org/pub/epel/epel-release-latest-7.noarch.rpm

• install required packages

  sudo yum install tito gcc make rpm-build rpmdevtools

To build latest untagged version from git, use:

tito build --rpm --test

To build latest tagged version from git, use:

tito build --rpm

RPMS are created in folder /tmp/tito including /tmp/tito/x86_64.