Enabling 64-bit kernel on Raspberry PI 4B

Geir Nøklebye

World Builder
Staff member
A recent update to Raspbian contains a 64-bit kernel that can easily be enabled by adding a single line to the system config file.

Since the Rasbian userland (where all applications run) are still 32-bit you are only going to experience small performance improvements running the 64-bit kernel; the most noticeable being better performance for disk operations. Certain applications heavy on floating points operations will also see improvements.
I have tested the 64-bit kernel for a couple weeks and it seems very stable.

To enable the 64-bit kernel cd to /boot and check that you have the file kernel8.img present.

If the file is present sudo vi config.txt, add the single line arm_64bit=1 to the end of the file and save it.
You can now reboot and on logging back in, in terminal type uname -a to check if you have enabled the 64-bit kernel. You should see something like this:

Linux <hostname> 4.19.75-v8+ #1270 SMP PREEMPT Tue Sep 24 18:59:17 BST 2019 aarch64 GNU/Linux

There is a project ongoing to port the Rasbian userland to 64-bit, and it is at this stage sort of runnable, but I have not tried it myself. Details in this thread
A 64-bit version of Gentoo should be available for the PI4 by now. Check the Rasbian forum for details.

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