Re: CVS commit: src/sys/kern

[Matthias Drochner <M.Drochner%fz-juelich.de@localhost>]

bouyer%antioche.eu.org@localhost said:
> I still believe drivers needs to get more informations from PMF to
> know what's going on. 

As a general philosophy, I'd prefer in most cases to
tell the driver exactly what to do. Otherwise we get
all kinds of creative abuse, as we have in the disk
spindown case.
It is also a matter of policy-implementation separation -
the driver shouldn't second-guess the user's or the higher
kernel code's intentions.

jmcneill%invisible.ca@localhost said:
>    3. Get rid of pmf_device_register completely, and treat  suspend/
> resume/shutdown as event handlers. 
ad%NetBSD.org@localhost said:
> 4. a message/event handler at the device level, so we don't have this
>    discussion every couple of months. 

We need both imho.
As I see it, we have two distinct ways how these driver functions
are called:
a)walking the device tree upwards or downwards, as pmf_suspend/
  resume do. This is needed at least for system sleep.
  It is relative expensive and relies on a lot of data structures
  to be still intact, thus it is less ideal for an emergency
  reboot.
b)without ordering constraints, as all the hooks. This could well be
  done with event handlers. At driver level, so that for 10 disks
  we don't get 10 memory allocations but just one call for all eg "wd"
  disks and one for all "sd"s. If done well, no big linked lists need
  to be scanned at event time. Reboot with/without poweroff are
  good candidates to be handled that way.

Whether a pmf_device_register function is used or another entry
in the cfdriver or cfattach struct, is secondary imo. I'd
stick with the former until things have settled a bit more,
because every change to the _DECL macros increases the mess we
already have there.

best regards
Matthias




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