On Fri, 2007-02-16 at 13:41 +0100, Ingo Molnar wrote: > * Eric W. Biederman <[EMAIL PROTECTED]> wrote: > > > So I propose we remove all assumptions from the code that we actually > > have an array of irqs. That will allow for irq_desc to be dynamically > > allocated instead of statically allocated saving memory and reducing > > kernel complexity. > > hm. I'd suggest to do this without changing request_irq() - and then we > could avoid the 'massive, every driver affected' change, right? > > i.e. because we'll (have to) have an nr_to_desc() and desc_to_nr() > mapping facility anyway, lets just not change the driver APIs massively. > There dont seem to be that many drivers that assume that irq_desc[] is > an array - are there? > > otherwise, in terms of the irqchips infrastructure and the API between > genirq and the irqchip arch-level drivers, this change makes quite a bit > of sense i think. > > or am i missing something fundamental?
Well, I don't want to see anything like desc_to_nr / nr_to_desc unless the number in question is a virtual number. That is, there is no way we should go that way and keep passing a HW number through request_irq. That would just be a total nightmare for powerpc and sparc at least. What we can do is generalize the powerpc virtual irq scheme though. You can see the implementation in arch/powerpc/kernel/irq.c starting from the definition of irq_alloc_host() though for some stupid reason, I've put all the documentation in include/asm-powerpc/irq.h so you might want to start there. Once the IRQ numbers are virtualized, it becomes easier to slowly migrate things to use irq_desc_t * while still having a virutal number available. Once everything has been migrated, we can then get rid of the virtual numbers completely except maybe for an optional 16 entries array for legacy cruft. Ben. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
