Reasonable/sane limits for kern.msgbufsize?

Empirically, I have found that for dmesg.boot to contain the full dmesg
from a verbose boot on one of my machines, starting from:

---<<BOOT>>---
APIC: Using the MADT enumerator.
Copyright (c) 1992-2021 The FreeBSD Project.
...

I need to increase kern.msgbufsize to above 200KiB (204800); so far,
262144 (256KiB) seems to work for stable/12.  (Actual size of
/var/run/dmesg.boot just now was 216929 -- 212KiB.)

Note that the default value is 96KiB (98304).

In this particular case, the machine has 256GiB RAM -- but kernel
address space (I expect) remains a constrained resource.

How much trouble am I asking for if I set

kern.msgbufsize=262144

in /boot/laoder.conf?

It might be cool to be able to do that only for a verbose boot, and have
a somewhat more reasonable value for a non-verbose boot....

[Rationale: I build FreeBSD often -- tracking head, stable/13 and
(currently) stable/12 daily.  I place salient information on a Web site;
that includes a copy of /var/run/dmesg.boot -- from a verbose boot.  But
I noted a while back that much of the first part of the latter was
missing; I only found out "how much" a few minutes ago.]

Peace,
david
-- 
David H. Wolfskill                              david@catwhisker.org
See "Truth Social"?  Read it as "Pravda" -- and adjust expectations accordingly.

See https://www.catwhisker.org/~david/publickey.gpg for my public key.