On Tue, 1 Mar 2005, Linas Vepstas wrote:
>
> > > - Additionally adds special token - abstract "iocookie" structure
> > > to control/identifies/manage I/Os, by passing it to OS.
> > > Actual type of "iocookie" could be arch-specific. Device drivers
> > > could use the iocookie structure without knowing its detail.
> >
> > Fine.
>
> Do we really need a cookie?
I think you do.
That pair might have to disable interrupts (if there are any issues about
concurrent accesses through a shared error bus). In that case, the cooke
might be the old "flags" value.
> > But many drivers don't need to save/restore interrupts around IO accesses.
> > I think defaulting these to disable and restore interrupts is a very bad
> > idea.
> > They should probably be no-ops in the generic case.
>
> Yes, they should be no-ops. save/resotre interrupts would be a bad idea.
But they may be part of that the architecture wants to do (imagine a
spinlock protecting a sub-segment of a bus - you need to disable
interrupts to avoid deadlocks).
Linus
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