Re: [PATCH] cardbus: revert IO window limit

From: Linus Torvalds
Date: Thu Jun 22 2006 - 12:15:53 EST




On Thu, 22 Jun 2006, Andrew Morton wrote:
>
> There is something bad happening in there. Presumably, this patch will
> break the ThinkPad 600x series machines again though.
>
> It'd be nice if this was related to
> http://bugzilla.kernel.org/show_bug.cgi?id=6725, but I guess not.
>
> Didn't all this stuff work in 2.4?

No, it's never worked on all machines.

What happens is that the IO window size just changes where things are
allocated, which breaks things on one machine and fixes it on another. The
reason tends to be some random hidden IO address that the kernel doesn't
know about.

So yes, that particular machine may have worked in 2.4.x. Then we fixed
something, and other machines started working, and that one broke.

I'd rather try to understand why the 256-byte IO window doesn't work on
that particular machine than try to just randomly change it to hide the
problem just on that machine again.

Linus
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