CVS commit: src/sys/arch

[David Young <dyoung%netbsd.org@localhost>]

Module Name:    src
Committed By:   dyoung
Date:           Fri Jun 26 23:40:27 UTC 2009

Modified Files:
        src/sys/arch/i386/i386: machdep.c
        src/sys/arch/sparc64/sparc64: machdep.c

Log Message:
During a normal shutdown, gracefully tear down arbitrary stacks of
filesystems and (pseudo-)devices, according to the algorithm at A3
and A4, below.

Proposed and discussed at
<http://mail-index.netbsd.org/tech-kern/2009/04/20/msg004864.html>.  No
objections.

During an emergency shutdown (e.g., shutdown -n, or after a panic),
shutdown is simple as always: filesystems are not sync'd or unmounted,
and devices are not detached.

It was necessary to change the order of operations during shutdown,
but the new order is more sensible: if a core dump is desired, then
cpu_reboot(9) dumps it first.  cpu_reboot(9) does not call legacy
shutdown hooks any longer: they can interfere with device detachment
and PMF shutdown, and very few legacy hooks remain.

Here is the old order of operations:

B1 sync filesystems and TOD clock
B2 unmount filesystems
B3 dump core
B4 detach devices
B5 run legacy shutdown hooks
B6 run PMF shutdown hooks
B7 suspend interrupts
B8 MD reboot/shutdown/powerdown

And here is the new order:

A1 dump core
A2 sync filesystems and TOD clock
A3 unmount one or more filesystems OR
   detach one or more devices OR
   forcefully unmount one filesystem OR
   skip to 5
A4 repeat at 3
A5 run PMF shutdown hooks
A6 suspend interrupts
A7 MD reboot/shutdown/powerdown

Tested on Dell Dimension 3000, Dell PowerEdge 1950, Sun Fire V120,
Soekris net4521 and net4801.

VS: ----------------------------------------------------------------------


To generate a diff of this commit:
cvs rdiff -u -r1.668 -r1.669 src/sys/arch/i386/i386/machdep.c
cvs rdiff -u -r1.242 -r1.243 src/sys/arch/sparc64/sparc64/machdep.c

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.