Re: [PATCH] Summit patch for 2.5.34

From: James Cleverdon (
Date: Mon Sep 16 2002 - 16:24:14 EST

On Monday 16 September 2002 08:55 am, Dave Jones wrote:
> On Thu, Sep 12, 2002 at 08:35:14PM -0700, James Cleverdon wrote:
> > Patch that allows IBM x440 boxes to on-line all CPUs and interrupt
> > routing for x360s. Fixed x360 ID bug.
> Couple questions/comments.
> - Is this the same summit code as is in 2.4-ac ?
> (Ie, the one that boots on non summit systems too)

Yes, save for the dynamic TPR enhancement. (Already addressed by Alan, etc,
in other postings.)

> - I believe the way forward here is to work with James Bottomley,
> who has a nice abstraction of the areas your patch touches for
> his Voyager sub-architecture.
> Linus has however been completley silent on the x86-subarch idea
> despite heavyweights like Alan and Ingo adding their support...
> If you go this route, James' base needs to go in first
> (converting just the in-kernel visws support). After which, adding
> support for Voyager, Summit and any other wacky x86esque hardware
> is a simple non-intrusive patch that touches subarch specific areas.
> - Some of the code you've added looks along the lines of..
> if (numaq)
> foo();
> else if (summit)
> foo2();
> else
> foo3();
> Would it be over-abstracting to have some form of APIC struct,
> defining pointers to various routines instead of lots of ugly
> if's/switches/fall-through's.
> However, the last point may be completley pointless after adapting to
> use what James B has come up with..
> Dave

All the if/else chains are in init code, where a few more microseconds for
some extra branches isn't important. However, a nice sub-arch abstraction
would be welcome.


James Cleverdon
IBM xSeries Linux Solutions
{jamesclv(Unix, preferred), cleverdj(Notes)} at us dot ibm dot com

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