[Bug 229188] Bhyve console hang on serial, works on stdio

[b***@freebsd.org]

https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=229188

Bug ID: 229188
Summary: Bhyve console hang on serial, works on stdio
Product: Base System
Version: CURRENT
Hardware: amd64
OS: Any
Status: New
Severity: Affects Some People
Priority: ---
Component: kern
Assignee: ***@FreeBSD.org
Reporter: ***@eicat.ca

I have a bulldozer (AMD 9590) running -CURRENT (a few days ago) that exhibits
some strange behavior lighting up a linux VM that we have transferred over from
Digital Ocean.

If it boots with console as stdio (-f argument), it runs. If it boots without
-f (console is a null-modem serial), then I get the following on the console
(and the boot never finishes)

[ 54.548000] serial8250: too much work for irq4
[ 57.412000] serial8250: too much work for irq4
[ 61.040000] [sched_delayed] sched: RT throttling activated
[ 61.044000] serial8250: too much work for irq4
[ 63.892000] serial8250: too much work for irq4
[ 66.760000] serial8250: too much work for irq4
[ 69.656000] serial8250: too much work for irq4

Now I've done some research on this message. According to old posts
(2009-2012-ish) Other virtual machines got this message from linux when they
were either delivering interrupts on the serial when the serial was empty _or_
they were emptying the serial buffer too quickly and interrupting for more
output.

On that latter point, apparently this is a legitimate failure mode of some
physical chips, so the was much pushback on the linux side that the VMs need be
fixed.

I don't see any published work arounds and I'd rather not leave screens running
the console of machines ... so ...

[b***@freebsd.org]

https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=229188

Mark Linimon <***@FreeBSD.org> changed:

What |Removed |Added
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Assignee|***@FreeBSD.org |***@FreeBSD.org