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.
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