Re: [2.2.8] undefined reference to `disable_irq_nosync' (+ fix)

[Alexander Viro]

On Fri, 14 May 1999, Matthew Wilcox wrote:

> I had a cunning thought a couple of weeks back which people seem to think
> will work, but no-one's done yet :-)
> 
> The problem is that if the SWP instruction (atomically read-and-write)
> hits in the cache, it will not go through to main memory, unlike earlier
> ARM processors.  Obviously, disabling the cache is going to take a big
> performance hit (particularly for those of us with 33MHz busses, argh).

Grrrmmm... Somewhere I've heard about SMP on a beast with really sucking
cache coherency... Wait a bit... Yup. Processor in question: KL-10.
OS: TOPS-10. They had a nasty time fighting with that problem and there
is a good paper on http://www.inwap.com/pdp10/paper-smp.txt about the
thing they did.