Re: Size of irq field

[Ian Campbell <ian.campbell@citrix.com>]

On Thu, 2015-04-02 at 18:05 +0300, Iurii Konovalenko wrote:
> Hi, Julien!
> 
> During bringing up Xen on Renesas Lager board we faced with problem.
> A lot of Xen sources relies on statement, that IRQ number is less then
> 256 and variables, parameters, fields etc. are of type uint8_t.

Please can you give some example of this?

Internally most irq stuff is unsigned int I think and "git grep
uint8_t.*irq -- xen" is not showing lots of hits, there are a few but
none which seem terribly scary or hard to fix.

>  But we
> can have IRQs, that are greater then 255, for example on RCar H2 SoC.
> Also, as I saw from one of your latest commits, GICv supports 1020
> physical interrupts.

This has always been true, in fact Julien's commit was reducing the
limit (which was too high), not increasing it.

>  As a result, overflow can occur. So it seems
> logical to increase all irq staff to uint16_t or uint32_t. We have
> local patches for increasing some structures, functions etc.
> But before pushing these patches I want to know your opinion, what do
> you think about this problem? What type should we use uint16_t or
> uint32_t? How to find all places where uint8_t type is used for IRQ?

We should certainly fix anywhere which is not using a large enough data
type.

Ian.