Re: [PATCH 00/16] dyn_array and nr_irqs support v2

[H. Peter Anvin]

Eric W. Biederman wrote:
> Yes.  I want the option of using those bits.  It might not be smart to
> use them to encode a physical location and the irq number but just
> having the option would be nice.

Urk!  First of all, there isn't enough space as we have already proven 
(on the machines where it actually matters there just aren't enough 
bits), but doing this kind of stuff *optionally* is going to hurt even 
worse.

Furthermore, this crap will break anyway the *next* time someone comes 
up with a new clever way to do interrupts -- and to truly get stable 
identifiers, we can't treat HyperTransport MSI as APICs anymore, yadda, 
yadda...

> Making /proc/interrupts useful without breaking user space is going to be
> an interesting challenge one of these days.

If changing to non-numbers in /proc/interrupts will break userspace, 
then userspace will have to deal with a numeric token in 
/proc/interrupts which will have to be looked up elsewhere (perhaps in a 
sysfs directory) to get a more meaningful index.

	-hpa
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