add an IPI which causes the target CPU to perform AST processing when
it returns to userspace.
- Add a way to get/set a private pointer in the shared interrupt header.
that is priority is rasied. Add a new spllowersoftclock() to provide the
atomic drop-to-softclock semantics that the old splsoftclock() provided,
and update calls accordingly.
This fixes a problem with using the "rnd" pseudo-device from within
interrupt context to extract random data (e.g. from within the softnet
interrupt) where doing so would incorrectly unblock interrupts (causing
all sorts of lossage).
XXX 4 platforms do not have priority-raising capability: newsmips, sparc,
XXX sparc64, and VAX. This platforms still have this bug until their
XXX spl*() functions are fixed.
tty structures, and on some machines (namely the DraCo internal lpt, and some
multi-i/o boards for Amigas and DraCos), tying spltty to the pretty high printer
interupt level would hurt serial performance.
On all affected ports but Amiga, spllpt() has been defined in machine/intr.h
to be spltty(), thus preserving old behaviour. Portmasters are encouraged to
change is, if they feel something else is better (e.g., one of its own were
possible).
(1) it was using 'max', and some functions use a variable
of that name (*sigh*), and
(2) that makes it easier to be a bit trickier, and only call
swpipl if changing the IPL.
