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Date:      Wed, 9 Oct 2024 06:25:52 +0000
From:      Vasily Postnicov <shamaz.mazum@gmail.com>
To:        freebsd-virtualization@freebsd.org
Subject:   Running Mezzano in bhyve
Message-ID:  <CADnZ6B=ex24mbGN3du6UuS84akJZAxTcG5xqt0HB0RN5S262cQ@mail.gmail.com>

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Hi! Mezzano is an operating system written in Common lisp. I would like to
test it in bhyve. When I launch it, it spins infinitely in a loop measuring
how many CPU cycles it makes in a unit of time (I understood it by adding
various debug messages).

The timer it uses is something called a PIT:
https://wiki.osdev.org/Programmable_Interval_Timer

The problem is, once the timer is configured it fires an interrupt only
once, while it obviously must fire interrupts constantly at some frequency
(100 Hz, as I understand from the code).

Is the PIT supported by bhyve? Does FreeBSD use it anywhere in its kernel?

BTW, Mezzano boots up fine on bare metal and in qemu, so the project is in
a working state, despite being abandoned.

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<div dir=3D"ltr">Hi! Mezzano is an operating system written in Common lisp.=
 I would like to test it in bhyve. When I launch it, it spins infinitely in=
 a loop measuring how many CPU cycles it makes in a unit of time (I underst=
ood it by adding various debug messages).<div><br></div><div>The timer it u=
ses is something called a PIT:=C2=A0<a href=3D"https://wiki.osdev.org/Progr=
ammable_Interval_Timer">https://wiki.osdev.org/Programmable_Interval_Timer<=
/a></div><div><br></div><div>The problem is, once the timer is configured i=
t fires an interrupt only once, while it obviously must fire interrupts con=
stantly at some frequency (100 Hz, as I understand from the code).</div><di=
v><br></div><div>Is the PIT supported by bhyve? Does FreeBSD use it anywher=
e in its kernel?</div><div><br></div><div>BTW, Mezzano boots up fine on bar=
e metal and in qemu, so the project is in a working state, despite being ab=
andoned.</div></div>

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