Attached is the patch and description that represents a current 
work-in-progress, removal of the 'irq' argument passed to all driver IRQ 
handlers.

As this patch demonstrates, the 'irq' argument is useless and 
practically unused.  The vast majority of drivers have this information 
elsewhere (struct pci_dev or private struct).  The cases where it is 
actually used are as follows:

* a couple Mac drivers have multiple IRQs, and use the irq argument for 
disambiguation purposes.  This can easily be remedied by moving that 
information into the info passed in the normal void* pointer.

* Several ancient ISA drivers, which mainly use it for 
printk-in-irq-handler purposes.  A couple use the irq argument as an 
index into a structure, which is a buggy approach.  I fixed up these.

This can be found in the 'hacking-irq-remove' branch of
git://git.kernel.org/pub/scm/linux/kernel/git/jgarzik/misc-2.6.git


Before I will even consider submitting this upstream, this patchset needs

* non-x86[-64] build fixes, and testing
* update the Mac drivers
* one more review pass, to make sure everything is kosher

so IOW, not anytime soon :)