Re: [patch 0/8] x86: UV - XPC fixes with related supportfunctionality V2.

From: Ingo Molnar
Date: Tue Nov 24 2009 - 02:19:46 EST



* Robin Holt <holt@xxxxxxx> wrote:

> > Regarding the patches - i still very much dislike how the code
> > interfaces to the 'BIOS'. The drivers/misc/sgi-xp/ code looks rather
> > messy.
> >
> > Why isnt a pure hardware interface exposed, as both hpa and me
> > suggested in the past?
>
> The information is stored on hardware (UV-Hub and RAM) outside this
> instance of hardware.
>
> The only safe way to access that hardware is via the GRU.
>
> No GRU resources are available to the BIOS.
>
> Ergo, this interface method with multiple passes is needed.
>
> If there is a better way, I am open to suggestions.

Erm, the better way is to not use the BIOS but to access those registers
that the BIOS accesses? (which is currently hidden by the BIOS)

In other words, we want to remove arch/x86/kernel/bios_uv.c and the
uv_bios_call*() APIs and replace them via clear implementations for
clear hardware abstractions. That 'bios message queue' thing is absolute
madness for example. But the type-opaque software API too.

Ingo
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