Interrupt handling changes, in discussion since February:

- Reduce available SPL levels for hardware devices to none, vm, sched, high.
- Acquire kernel_lock only for interrupts at IPL_VM.
- Implement threaded soft interrupts.

branches: 1.12.8; 1.12.24; 1.12.26; 1.12.28; 1.12.30; 1.12.36;
Convert the NetBSD/cats port to use generic TODR.

This gets rid of the now-unneded "todclock" and "todservice" attributes
from the footbridge device files, which should allow netwinder to build
again after its conversion to generic TODR.

Resulting kernel verified to boot up OK on gxemul (after my recent
fixes of the gxemul package to emulate free-running timers).

branches: 1.11.18; 1.11.48; 1.11.50;
Use the generic irq_dispatch.S

Checkin new interrupt handling code for the footbridge.
This is based upon Jason's work on xscale.

Most of the interrupt handling code is now written in C using an asm stub to
call into the C code.

spl* now only updates a software mask, and does not update the hardware,
this should be much faster.

The new code works well on cats, it's untested on netwinder, but should work.

The code implements generic soft interrupts.

More work is still required to bring the isa interrupt handling code upto
scratch currently all isa interrupts are handled at IPL_BIO on the footbridge.
This may cause isa interrupts to be handled later than they should be.
I plan to fix this in the near future.

branches: 1.9.2;
Make sure the footbridge device has the interface attribute.

Use the bus_space_generic bus space ops.

G/c FOOTBRIDGE option.

- convert usage of "defopt" to "defflag" where the relevant option does
not support a value (e.g., it's to be used as "options FOO" instead of
"options FOO=xxx"). options that take a value were converted to
defparam recently.
- minor whitespace & formatting cleanups

branches: 1.5.2; 1.5.4; 1.5.10;
Remove defopt EBSA285.
Move the files from footbridge that are cats specific.
Remove EBSA285 kernel as people should be able to use the generic cats kernel for EBSA285 systems.

Move netwinder_machdep.c to files.netwinder. Eliminate opt_netwinder.h and
use #ifdef netwinder insead. XXX ebsa285_machdep.c should move to the cats
directory and files.cats

Move defopt FOOTBRIDGE to where it really should be in files.footbridge, which is where I should have left it.

Move the footbridge dir out of arm32 into arm.

Add a files.footbridge for inclusion by cats and netwinder. This is to make moving of the footbridge dir easier (when it eventually moves from arm32)

Also remove EBSA285 defopt from the netwinder file as the netwinder isn't an eval board.