4.3 hangs

[terryl at tekcrl.UUCP]

In article <460 at sdcc7.ucsd.EDU> muller at sdcc7.ucsd.EDU (Keith Muller) writes:
>
>i had that problem also. It is bogus microcode in the cs21/f2 version. The
>board goes into a infinite loop while it has the unibus doing dma output.
>The reason it never shows up on 4.2 is that driver did not do dma on output.
>Next time it happens flip reset switch (position 1) on the cs21 from normal
>to reset and back. When the offending dmf is found the system will come
>back to life. Of course the dmfs are now in a weird state, but at least you
>can shut down cleanly. Bug emulex for a prom upgrade.

     Another UNIBUS board that can do the same thing as described above is the
Interlan NM10 ethernet card. Many times in the driver, the driver will issue a
command to the board, and instead of letting the board interrupt the cpu when
it's done with the command, will sit in a null loop waiting for the ready bit
to come true. If the ready bit never comes true, it just sits in this null loop
forever.

     A good thing to notice when the system just "seems to hang" is to try and
halt the system if you can. If you can halt the system, take a look at the PC
when it halted. This is how we found out about the Interlan card hanging the
system. It was always happening in the routine ilrint().