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SubjectRe: question regarding cacheline size
On Thu, Sep 07, 2006 at 12:00:39PM -0400, Jeff Garzik wrote:
> Tejun Heo wrote:
> >arch/i386/pci/common.c overrides cacheline size to min 32 regardless of
> >actual size. So, we seem to be using larger cacheline size for MWI
> >already.
>
> It clamps the minimum size to 32, yes, but on modern machines common.c
> configures it to a larger size.
>
>
> >Jeff pointed out that there actually are devices which limit CLS config.
> > IMHO, making PCI configure CLS automatically and provide helpers to LLD
> >to override it if necessary should cut it.
>
> We still have to add a raft of quirks, if we start automatically
> configurating CLS... Also, many PCI devices hardcode it to zero.

That's not a problem. As long as they silently discard the writes to
the CLS register, we'll cope. If they decide to flip out, then we have
the no_cls flag.

> If we start configuring CLS automatically, I forsee a period of breakage...

Probably. But it's something we should have done a long time ago.
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