Subject: Re: IPL_* and IST_* constants
To: Charles M. Hannum <email@example.com>
From: Chris G Demetriou <Chris_G_Demetriou@UX2.SP.CS.CMU.EDU>
Date: 03/19/1996 10:41:00
> That's not what I was referring to. I was referring specifically to
> drivers pulling in more files than they need. There is already
> precedent for cpu.h pulling in psl.h.
On the i386, this is true. it doesn't appear to be true on several
ports, of which the Alpha is only one.
> If people want their drivers to be portable to the Alpha, they will
> access these constants by getting them via <machine/cpu.h>.
> That's poor. Drivers should be able to access those constants (and,
> I'd say, the spl*() prototypes and/or inline definitions) without the
> rest of the cruft in cpu.h.
Similarly, it's poor to require that people who maintain ports make
definitions about a machine-specific feature, e.g. the "processor
status longword" available to more code than actually needs it...
> I propose the creation of <machine/intr.h>, which would contain the
> IPL_* and IST_* constants, as well as any definitions necessary to use
> the spl*() and setsoft*() functions/macros.
This sounds like a good idea, though it would be nice if the other
things that were to go in there (i.e. the full set of spl* and
setsoft* definitions to be used by drivers, at least) were
I can think of:
I _don't_ think that something spl0() or splnone() should be available
for driver use... I'm sure there are a bunch more; what am i missing?
It might also be nice if there were a more general way to schedule
software interrupts... 8-)