One of the groups ran across some mysterious behavior with the `tlbp'
instruction that turned out to be the result of a hardware bug.
It wasn't clearing the "probe failed" bit on a successful probe, so if
you did multiple TLB_Probe calls without an intervening TLB_Read or
TLB_Write (which happen to clear that bit as a side effect) the probe
may falsely appear to fail without finding anything.
A new System/161 release (0.98) has been issued and deployed.
This has two implications:
(1) if a mysterious problem you've been seeing mysteriously
disappears and never comes back, and could conceivably be
related to this issue, this change may be why it disappeared.
(2) if you're working at home and/or have compiled your own
System/161 for some other reason, you should download and
install the new version.
--
- David A. Holland / dholland(a)eecs.harvard.edu
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