Ported from DragonFlyBSD, but this target had originally existed in
Linux kernel. See below for details.
https://www.kernel.org/doc/Documentation/device-mapper/delay.txt
Due to "tick" in hz(9) not working (which results in dmdlthread spinning
forever in _submit_queue() without dp extracted from delayed list
and queued into submit list), this hasn't been hooked to dm.kmod yet.
taken-from: DragonFlyBSD
properties (similar to what the "dsrtc" driver does), and provide
DT compat strings corresponding to those models. Allow config flags
to specify the model for non-FDT platforms (also like "dsrtc").
Ported from DragonFlyBSD, but this target had originally existed in
Linux kernel. See below for details.
https://www.kernel.org/doc/Documentation/device-mapper/dm-flakey.txt
Due to two technical issues, this hasn't been hooked to dm.kmod yet.
1) "tick" in hz(9) not working.
2) Unable to use ->b_private in nestiobuf callback when it's already
used for mbp (see HAS_BUF_PRIV2).
taken-from: DragonFlyBSD
the system is shutting down or rebooting.
- Set this global in a new function called kern_reboot(), which is currently
just a basic wrapper around cpu_reboot().
- Call kern_reboot() instead of cpu_reboot() almost everywhere; a few
places remain where it's still called directly, but those are in early
pre-main() machdep locations.
Eventually, all of the various cpu_reboot() functions should be re-factored
and common functionality moved to kern_reboot(), but that's for another day.
- Add a mutex around the TODR, and provide lock/unlock/lock-owned
functions to manipulate it.
- Rename inittodr() to todr_set_systime() and resettodr() to
todr_save_systime() to better reflect what they do. These functions
are intended to be called with the TODR lock held, which will allow
for a pattern like:
-> todr_lock()
-> todr_save_systime()
-> [do machine-dependent stuff to sleep/suspend]
-> [magically awaken]
-> todr_set_systime(...)
-> todr_unlock()
- Provide historically-named wrappers inittodr() and resettodr() that
do the dance of acquiring / releasing the lock around the actual
substance.
NOTE: resettodr()'s use of the TODR lock is currently disabled (and
todr_save_systime() does not assert it's held) until such time as
issues around shutdown / reboot under duress can be addressed.
- As previously defined, it was not possible to return an error from the
back-end RTC driver. Make it a real function so that it can do so.
- Only the mc146818 and mk48txx drivers used it (for historical reasons).
Centralize the logic for how it's used in kern_todr.c (and make it private
to that file) for consistency.
