Finding the Linux kernel version / commit used by Petalinux, and acquiring the kernel source

Updated: May 14, 2023

This post shows how you can find the kernel version used in a Petalinux build - not just the numeric version like 4.19, but the exact git commit. It also shows how to download the kernel source for that version.

Kernel version

Execute `uname -a` on a running Petalinux image on the FPGA. Here, the output indicates that the kernel version is 4.19 and that this Petalinux image was built on Thursday October 21 2021, at 22:04:57 UTC.

# uname -a 
Linux 4.19.0-xilinx-v2019.1 #1 SMP Thu Oct 21 22:04:57 UTC 2021 aarch64 aarch64 aarch64 GNU/Linux

Kernel commit

cd to your Petalinux installation directory - this is the directory containing the settings.sh file you source to activate the Petalinux tools.

From here, cd into components/yocto/source/arch/layers

Replace the italic arch with the CPU architecture that your Petalinux build is running on:

- 'arm' for 32-bit ARM cores, like on the XC7S PS

- 'aarch64' for 64-bit ARM cores, like on the Ultrascale/+ PS

- 'microblaze_full' and 'microblaze_lite' for Microblaze softcores

From here, open the file meta-xilinx/meta-xilinx-bsp/recipes-kernel/linux/linux-xlnx_2019.1.bb in a text editor. Replace 2019.1 with the Petalinux version you're using.

This file will contain:

LINUX_VERSION = "4.19"
SRCREV ?= "9811303824b66a8db9a8ec61b570879336a9fde5"

Indicating that Petalinux 2019.1 uses kernel 4.19, and that specific git commit in the linux-xlnx repository.

This file may have moved around in newer Petalinux versions. If you can't find it at the path described above, you can cd to components/yocto/source/arch/layers and run a search for the commit:

grep -rIFe SRCREV | grep linux-xlnx

This does a recursive search for all occurrences of 'SRCREV', then narrows it down to just matches in files that had 'linux-xlnx' in their name.

Acquiring kernel sources

Download the linux-xlnx repository, and then checkout the commit that you want:

git clone https://github.com/Xilinx/linux-xlnx.git
cd linux-xlnx
git checkout 9811303824b66a8db9a8ec61b570879336a9fde5

References:

- The Xilinx graphic is from [link]