includes one of bus_at386.h and bus_pc98.h. Becuase only bus_pc98.h
supports indirect pio and bus_at386.h is identical to old bus.h, there
is no functional change in PC-AT's kernels. That is, it cannot cause
performance loss.
Submitted by: nyan
Reviewed by: imp
bde and luoqi provided useful comments for earlier version.
Historically, the documentation of extended asm was lacking, namely you
should NOT specify the same register as an input, and a clobber.
If the register is clobbered, it should be specified as an output as well,
e.g., by linking input and output through the "number" notation.
(Beware of lvalues, some local variables needed...)
URL:http://egcs.cygnus.com/faq.html
In versions up to egcs-1.1.1, the compiler did not even warn about it,
but it was liable to output bad code. Newer egcs are pickier and simply
refuse to swallow such code.
Note, since *addr changes, it needs to be an output operand.
We might be excessive in saying that all memory has changed.
Obtained from: OpenBSD
w/extra thanks to Marc Espie <Marc.Espie@liafa.jussieu.fr>
behavior slightly.
If machine/bus.h is included, but neither bus_memio.h nor bus_pio.h
are included, then behave as if both were included.
This won't change existing drivers, all of which include one or more
of bus_{p,mem}io.h, but will allow drivers from other systems to come
over with fewer changes. I freely admit that this might not be
optimal for some drivers, but those drivers can be optimized for
FreeBSD after the initial bringup happens.
Without the change, there is a bug that preclude drivers from
compiling with strange warning/errors.
I've been running this here for a while now w/o ill effects.
Reviewed by: gibbs
Not objected to by: bde, arch@ list.
