merge bouyer-xenpvh to HEAD

[Manuel Bouyer <bouyer%antioche.eu.org@localhost>]

Hello,
As you've probably noticed, I've been working in the bouyer-xenpvh on
improving the work started by cherry@ on Xen PVHVM support. The main goal
was to be able to have it in GENERIC, so that we don't need to distribute
yet another kernel. This is also a step toward PVH support.
Right now in the branch there is a GENERIC_XENHVM config, but it's
only to ease checking that GENERIC without Xen support stil builds and boot.
It has been tested on amd64 native, PV domU, HVM domU and PV dom0.
It has been tested on i386 native, PV domU and HVM domU.

The branch covers src/common and src/sys but the changes are in
sys/arch/{amd64,i386,x86,xen}/ (there is a XEN -> XENPV in
common/lib/libc/arch too).
You can see the diff with
cvs rdiff -kk -u -rbouyer-xenpvh-base1 -rbouyer-xenpvh src/sys

In amd64 and i386, the main change is that there is less #ifdef XEN
in assembly (and some headers and C files in x86), as we can now use the
native ci_ipending for Xen events too.
I also took the opportunity to factor some common code, like cpu_initclocks()
and associated function pointers.
Of course the */conf/ files had to be adjusted too, but there is less
duplicate entries now. But there are !xenpv conditions in non-xen file.*

Also, on amd64 the cli/sti based spllower is gone, we always use the
cmpxchg8 based one.

vm_guest got new types and associated sysctl value: XenPV, XenPVH.
XenHVM and XenPVHVM.

There are 3 new functions pointers to struct pic:
pic_intr_get_devname, pic_intr_get_assigned, pic_intr_get_count.
This is a step towrard better integration between native interrupts and
events, and allows Xen events to show up in 'intrctl list' on PVHVM.

On the Xen PV side, this gives us __HAVE_FAST_SOFTINTS and kernel
preemption (except on dom0 where MULTIPROCESSOR is still disabled,
some dom0 stuff is still not MP-safe yet).
For this I had to move parts of x86/x86/intr.c to a new x86/x86/x86_softintr.c.


If there's no objection I'd like to merge this to HEAD this week-end.

-- 
Manuel Bouyer <bouyer%antioche.eu.org@localhost>
     NetBSD: 26 ans d'experience feront toujours la difference
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