Add an ability to set dumpdev via loader(8) tunable.
MFC r272747:
Revert r156046. We support setting dumpdev via loader tunable again.
Also change default disk name to ada.
- dumpon utility has not used kern.dumpdev sysctl
since rev. 1.14 (sbin/dumpon/dumpon.c) when phk@
updated it to use the DIOCSKERNELDUMP ioctl [1]
- remove obsolete reference to sysctl(3)
While I am there, fix two style nits:
- use .Nm instead of `dumpon'
- change NOTES to IMPLEMENTATION NOTES, to bring
it in line with recommended section headings in
mdoc(7)
Original patch by: Martin Faxer <gmh003532brfmasthugget.se> [1]
PR: docs/39293
Approved and Reviewed by: des (mentor), re (scottl, bmah)
Caveats:
The new savecore program is not complete in the sense that it emulates
enough of the old savecores features to do the job, but implements none
of the options yet.
I would appreciate if a userland hacker could help me out getting savecore
to do what we want it to do from a users point of view, compression,
email-notification, space reservation etc etc. (send me email if
you are interested).
Currently, savecore will scan all devices marked as "swap" or "dump" in
/etc/fstab _or_ any devices specified on the command-line.
All architectures but i386 lack an implementation of dumpsys(), but
looking at the i386 version it should be trivial for anybody familiar
with the platform(s) to provide this function.
Documentation is quite sparse at this time, more to come.
Sponsored by: DARPA, NAI Labs
Details:
Dumpon now opens the device and uses ioctl(DIOCGKERNELDUMP) to set it
to be the dumpdevice. When "off" is set, /dev/null is used.
This allows obtaining crash dumps from the panics occured during late stages
of kernel initialisation before system enters into single-user mode.
MFC after: 2 weeks
* Remove the text which states only devices with minor number 1 can be used
- this is no longer true.
* Mention that dumpon(8) cannot be used to capture dumps from panics during
kernel initialization.
* /dev/wd -> /dev/ad
PR: 19848
Submitted by: Udo Erdelhoff <ue@nathan.ruhr.de>
Reviewed by: sheldonh
least one reviewer is now unhappy with, since it contains incomplete
and misleading advice that is not easy to correct.
The net effect of this commit and the previous commit is to simply
remove all discussion of setting dumpdev to catch crash dumps
prior to entering user mode.
