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Updated kernel with freeze bugfix

Posted: 05 Mar 2020, 15:20
by lukas
From the very beginning of the Revolution Pi project, we have strived for an open and transparent manner in dealing with bugs and mistakes. In this vein we would like to make the following announcement.

Over the past months we have received reports that Revolution Pi machines occasionally freeze. In an industrial setup that is obviously a no-go. One customer furnished us with stresstest scripts that allowed us to reproduce the freeze issues in our lab and analyze them with a JTAG debugger.

The root cause turned out to be a mistake in the bootloader provided by the Raspberry Pi Foundation: It erroneously leaves the USB interrupt enabled when handing over control to the Linux kernel. This not only causes freezes under certain complex conditions, but also negatively impacts the system's overall performance. For details please refer to the bugfix which we have submitted for the kernel.

An update for kernel 4.9 containing the bugfix is now available in our apt repository. In the very near future, we will make a kernel 4.19 available which also contains the bugfix. It is currently undergoing a continuous stresstest on a series of machines because we would like to avoid publishing a solution which might turn out to be half-baked.

We would like to express our gratitude towards our customers for their patience and loyalty. We explicitly solicit feedback if freezes or other issues still occur after the kernel update.

Re: Updated kernel with freeze bugfix

Posted: 22 Mar 2020, 13:05
by lukas
To verify that the updated kernel has been installed, invoke "dpkg -l raspberrypi-kernel": It should report version 9.20200228-4.9.76+revpi1. A reboot is necessary to activate the kernel. Afterwards, "dmesg" and "uname -a" will report the build date "Fri, 28 Feb 2020 15:17:03 +0100".

The bugfix will land in Linux 5.7. In April it will also automatically be backported to the Longterm Release Kernels. Until then, customers who build their own kernel may apply commit bd59b343a9c9 with "git cherry-pick".