From owner-freebsd-virtualization@freebsd.org  Sun Oct 28 14:20:14 2018
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From: Paul Webster <paul.g.webster@googlemail.com>
Date: Sun, 28 Oct 2018 14:20:02 +0000
Message-ID: <CADdqeiPHi8b-t3VWzKXGiDsV5WEH89yBnEYD8Qyj5Z9wT1YSLg@mail.gmail.com>
Subject: Information regarding CSM (If having issues may be worth checking
 out!)
To: "freebsd-virtua." <freebsd-virtualization@freebsd.org>
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I have spotted quite a few questions as of late about getting CSM to work
(with anything in some cases), I just thought I would drop into the list
that in fact CSM is BIOS emulation mode, meaning it makes the UEFI act like
a BIOS from the point of view of the OS, and is really only useful for
special cases.

For those of you that for some reason are trying to boot Linux on it, stop
you are almost certainly  doing something very wrong.

You should always try standard UEFI as a FIRST OPTION, if that does not
work but your target OS supports GRUB then great start using bhyve-grub2 to
do the boot, this will cover almost all use cases for anything made within
the last 5 years.

Just thought it was worth mentioning for if anyone was getting confused as
to what CSM was actually for :-)

-- Special thanks(for explaining this to me in the first place) to:
debdrup  @IRC