From owner-freebsd-dtrace@freebsd.org  Wed Oct 31 18:10:19 2018
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Date: Wed, 31 Oct 2018 19:10:09 +0100
From: Andreas Longwitz <longwitz@incore.de>
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To: Mark Johnston <markj@freebsd.org>
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Subject: Re: Why my DTrace script does not work after installing a new kernel
 without reboot
References: <5BD4E965.9040006@incore.de> <20181027225339.GA4191@spy>
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In the meantime I found the answer to my question.

> Does your patch change the layout of the timeout structure?  If so, the
> problem is that dtrace(1) is using the CTF from kern.bootfile, but that
> doesn't match the layout of the structures used by the running kernel.

dtrace() gets the CTF of the kernel and kernel modules from the
pathbames returned by kldstat(2). In my case they all start with
'/boot/kernel/' because the kernel was loaded from that place. This can
be veryfied with 'kldstat -v'. The output does not change after buildung
a new kernel and the kernel itself does nit use the variable
kern.bootfile.

-- 
Andreas Longwitz