Subject: Re: NetBSD-1.5A on dual cpu SS20: panic: lockmgr: no context
To: None <>
From: Simon J. Gerraty <>
List: tech-smp
Date: 06/29/2000 22:39:45
> >    panic: lockmgr: no context
> True. MP hypersparc machines all do this. The problem is in the smp
> version of the cache flush routines: pages must remain mapped in the
> MMU until the page cache flushes are done on all CPUs. Currently,
> the primary CPU races ahead and unmaps a page before the other CPUs
> get around to flushing it from their caches.

Does this mean we need ref counting (or moral equiv) somewhere?  Each
cpu decrements the count as it does the flush and the last one does
the unmap?

I assume there is an inter cpu message to cause the flush to happen,
so cpu's which don't have a cache entry, still get a chance to
decrement the ref count.

Of course I don't claim to know anything about the hardware involved