[5448] in bugtraq
More info on SPARC CPU bug
daemon@ATHENA.MIT.EDU (Charles M. Hannum)
Fri Oct 24 20:52:36 1997
Date: Fri, 24 Oct 1997 20:23:57 -0400
Reply-To: "Charles M. Hannum" <mycroft@MIT.EDU>
From: "Charles M. Hannum" <mycroft@MIT.EDU>
To: BUGTRAQ@NETSPACE.ORG
I have so far only been able to reproduce the hang on 170 MHz SS5s. I
have *not* been able to reproduce it on 85 MHz SS5s, 110 MHz SS4s,
Ultras, Classics, or pre-4m machines.
Specifically, the CPU that hangs is identified as a MB86907 (made by
Fujitsu), running at 170 MHz. It hangs when running the same code
under either Solaris 2.5.1 or NetBSD 1.3_ALPHA, so I believe the bug
is not OS-related.
As far as I can tell, the CPU wedges completely; all response from I/O
peripherals is dead, including L1-A on the keyboard and break on a
serial console.
To review, the sequence of instructions that causes the hang is:
L1:
b,a L1
retl
I have not exhaustively tested other instructions in the branch delay
slot, but `ret' and `nop' also appear to `work' (i.e. cause the hang).
It appears to be the branch instruction alone that's responsible for
the hang. A non-annulled branch does not have the same effect.
