[Xenomai] Xenomai: halcmd[1311] cannot map MAYDAY page

John Allwine john at allwinedesigns.com
Thu Dec 14 18:07:49 CET 2017

I'm using the latest machinekit image for the 3.8 kernel on the Beaglebone
Black (
It's using xenomai 2.6.3. I follow the steps in this document to set up
machinekit as a systemd service:

When I start machinekit manually after bootup, it seems to work fine. When
the services are started during boot up as a systemd service, I get the
following error (I can provide the full stack trace if that would help):
[ 19.501859] Xenomai: halcmd[1311] cannot map MAYDAY page
[ 19.956681] Unable to handle kernel NULL pointer dereference at virtual
address 00000004
[ 19.965136] pgd = de414000, hw pgd = de414000
[ 19.969675] [00000004] *pgd=9e7c4831, *pte=00000000, *ppte=00000000
[ 19.976229] Internal error: Oops: 817 [#1
<https://github.com/machinekit/machinekit/issues/1>] THUMB2
[ 19.981128] Modules linked in: g_ether libcomposite cpufreq_userspace

I filed this issue on machinekit's github repo as well:

Any thoughts on what the problem could be? Or how to debug this further?


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