Let’s suppose we have a testing suite which runs on Linux and it might lead into system crash during its execution, which is the typical case of testing suites triggering specific syscalls and stress kernel features. We want to keep track of our execution, to eventually recover system when it’s needed. We also want to test our features on specific kernel version.
kirk provides a robust support for this scenario, thanks to the Qemu integration that recognize kernel panics, oops, timeouts, reboots VM and it keeps track of current running tests. The same result can be reached via SSH, but we won’t cover this option here.
In this guide we will take a look at the described scenario and we will learn how to use kirk in order to run a testing framework on linux kernel.
We will consider using LTP, as we know it could crash our kernel. First of all, each kirk framework must implement Framework class and its definition must be placed inside the libkirk folder. Framework implementation for LTP can be found here.
A typical LTP execution on host via kirk can be done as following:
kirk -f ltp:root=/opt/ltp -r syscalls
But it doesn’t provide any control over Kernel panic, oops, freeze, etc. For this reason we need to build fs/kernel images in order to run tests via Qemu.
Buildroot project provides an easy and powerful way to build images supported
by Qemu. Our minimum requirement is gcc >= 8, then we can start building
our images with the following commands:
cd $BUILDROOT
make qemu_x86_64_defconfig
make menuconfig
We need to install LTP inside the buildroot image (notice that we need to give enough space to FS image, since we have LTP installed):
Host utilities ->
host qemu -> yes
Virtual filesystem support -> yes
Target packages ->
Debugging, profiling and benchmark ->
ltp-testsuite -> yes
Filesystem images ->
exact size -> 500MB
Then we can build the images:
make -j16
Sometimes gcc-11 compile causes some errors. In this case, gcc-12
can be used:
Toolchain ->
GCC compiler Version (gcc 12.x) ->
gcc 12.x -> yes
Now that we have both FS and kernel images, we can use kirk to run commands inside virtual machine.
export IMAGE=$BUILDROOT/output/images/rootfs.ext2
export KERNEL=$BUILDROOT/output/images/bzImage
kirk -s qemu:image=$IMAGE:kernel=$KERNEL:user=root:prompt='# ':options='-append "rootwait root=/dev/vda console=ttyS0" -net nic,model=virtio -net user' \
-c "ls -la /" \
-v
Notice that we specified prompt='# ', since the first busybox prompt string is
# . This is really important because first prompt string is used by kirk to
recognize if we logged in or not.
The option -append "rootwait root=/dev/vda console=ttyS0" is needed to tell
kernel what is our root device and what is our serial console,
-net nic,model=virtio -net user is needed in order to communicate with
network.
Command output will be the following:
ls -la /
total 25
drwxr-xr-x 18 root root 1024 May 31 12:08 .
drwxr-xr-x 18 root root 1024 May 31 12:08 ..
drwxr-xr-x 2 root root 2048 May 31 12:08 bin
drwxr-xr-x 8 root root 12280 May 31 12:09 dev
drwxr-xr-x 5 root root 1024 May 31 12:08 etc
drwxr-xr-x 3 root root 1024 May 31 12:08 lib
lrwxrwxrwx 1 root root 3 May 31 11:43 lib64 -> lib
lrwxrwxrwx 1 root root 11 May 31 11:59 linuxrc -> bin/busybox
drwx------ 2 root root 12288 May 31 12:08 lost+found
drwxr-xr-x 2 root root 1024 May 9 20:38 media
drwxr-xr-x 2 root root 1024 May 9 20:38 mnt
drwxr-xr-x 2 root root 1024 May 9 20:38 opt
dr-xr-xr-x 99 root root 0 May 31 12:09 proc
drwx------ 2 root root 1024 May 31 12:09 root
drwxr-xr-x 4 root root 180 May 31 12:09 run
drwxr-xr-x 2 root root 1024 May 31 11:59 sbin
dr-xr-xr-x 12 root root 0 May 31 12:09 sys
drwxrwxrwt 2 root root 80 May 31 12:09 tmp
drwxr-xr-x 6 root root 1024 May 31 12:08 usr
drwxr-xr-x 4 root root 1024 May 31 12:08 var
0-pQlWoxTSyF
Exit code: 0
Now we are ready to run an LTP testing suite using kirk:
export IMAGE=$BUILDROOT/output/images/rootfs.ext2
export KERNEL=$BUILDROOT/output/images/bzImage
kirk -f ltp:root=/usr/lib/ltp-testsuite \
-s qemu:image=$IMAGE:kernel=$KERNEL:user=root:prompt='# ':options='-append "rootwait root=/dev/vda console=ttyS0" -net nic,model=virtio -net user' \
-r syscalls \
-v
If everything is fine, we will see the running LTP syscalls testing suite.