Re: [RFC 0/4] dynamically allocate arch specific system vectors

Ingo Molnar
2008-09-14T15:36:05Z

* Dean Nelson <dcn@sgi.com> wrote:

> On Mon, Aug 11, 2008 at 12:39:22PM -0700, Eric W. Biederman wrote:
> >
> > Although I am not at all convinced that dynamic allocation of
> > the vector number (instead of statically reserving it makes sense).
>
> We (SGI) need somewhere around eight vectors.
>
> There are two kernel modules, sgi-gru and sgi-xp (in drivers/misc),
> that each need two vectors. And there's the broadcast assist unit
> (BAU) that is involved in tlb shootdown on uv, which currently uses
> statically reserved vector 0xf8 (UV_BAU_MESSAGE -- see uv_bau_init()).

while i understand the UV_BAU_MESSAGE case (TLB flushes are special),
why does sgi-gru and sgi-xp need to go that deep? They are drivers, they
should be able to make use of an ordinary irq just like the other 2000
drivers we have do.

> I know of a debugger that also uses 0xf8 because it was previously
> available until UV_BAU_MESSAGE came along. The BAU would be happy with
> a dynamically allocated system vector. We have a couple of other
> things in the works that also need vectors.

which debugger is this?

Ingo