Re: 2.6.19-rc <-> ThinkPads

Michael S. Tsirkin
2006-11-01T19:34:30Z

Quoting r. Linus Torvalds <torvalds@osdl.org>:
> Subject: Re: 2.6.19-rc <-> ThinkPads
>
>
>
> On Wed, 1 Nov 2006, Andi Kleen wrote:
> >
> > Ok please revert the i386 patch for now then if it fixes the ThinkPads.
> > The x86-64 version should be probably fixed too, but doesn't cleanly. I will
> > send you later a patch to fix this there properly.
>
> Actually, I should have just fixed the ordering. I did some cleanups too,
> but those are unrelated (except in the sense that I wanted to look at the
> assembly code, and the cleanups made the code generation at least half-way
> sane!)
>
> I've pushed out the changes, but here is the part that may or may not
> matter for anybody who wants to test it if they don't use git or if it
> hasn't mirrored out yet. Michael? Martin?

I pulled the latest git, and seems to work for me, thanks.
This still could be a false negative (happened already) so I'll
continue using this, and will post the results.

> Andi: I think the patches should work pretty much as-is for x86-64 too,
> since all the issues would seem to be similar.
>
> I'm not entirely happy with "ioapic_write_entry()" now either (if we
> change an entry that was already unmasked, we should probably mask it
> first by writing the low word with the mask bit set, then write the high
> word, and then write the low word again), but
>
> - this makes us match the ordering we _used_ to have, so if the cleanup
> broke things for people, this should unbreak it, and at least not be
> any worse than it used to be.
>
> - when we write new unmasked entries, they all _should_ have been masked
> before, so hopefully the "change a unmasked entry while it's unmasked"
> case doesn't actually ever happen. But I didn't actually _check_.
>
> Somebody should look into that case. Does anybody feel like they want to
> learn more about the IO-APIC? Halloween is over and gone, but if you want
> to scare small children _next_ year, telling them about the IO-APIC is
> likely a good strategy.
>
> Linus

Hmm, sounds interesting :)
Is this a good place to start (I'm feeling lucky hit for IO-APIC)?
http://www.intel.com/design/chipsets/datashts/290566.htm

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MST