Re: Several minor questions (12.0-amd64)

Beeblebrox zaphod at berentweb.com wrote on Sat Apr 22 06:04:01 UTC 2017 :

> 3. Under one scenario, I'm getting a kernel panic but I cannot dump because
> busybox states "no dumpdev specified" which means rc.conf (where I have
> dumpdev set) has not been read yet. How can I pass dumpdev wile in busybox
> command line so that ">dump" does its job?

/boot/loader.conf allows for an earlier time frame
for having dumpdev. For example I have:

# more /boot/loader.conf
geom_label_load="YES"           # File system labels (see glabel(8))
kern.cam.boot_delay="10000"
dumpdev="/dev/label/BPIM3swap"

Supporting documentation is from:

https://www.freebsd.org/cgi/man.cgi?query=loader&sektion=8&apropos=0&manpath=FreeBSD+11.0-RELEASE+and+Ports

and includes the following about dumpdev:

LOADER(8)		FreeBSD	System Manager's Manual		     LOADER(8)


NAME

     
loader
 -- kernel bootstrapping final stage

. . .

   BUILTIN ENVIRONMENT VARIABLES

     The loader	has actually two different kinds of `environment' variables.
     There are ANS Forth's environmental queries, and a	separate space of
     environment variables used	by builtins, which are not directly available
     to	Forth words.  It is the	latter type that this section covers.
. . .
     dumpdev   Sets the	device for kernel dumps.  This can be used to ensure
	       that a device is	configured before the corresponding dumpdev
	       directive from rc.conf(5) has been processed, allowing kernel
	       panics that happen during the early stages of boot to be	cap-
	       tured.




===
Mark Millard
markmi at dsl-only.net