V8.x-PRE2 Serious PUC problem - Heads Up!

[Karl Denninger]

perryh at pluto.rain.com wrote:
> Karl Denninger <karl at denninger.net> wrote:
>   
>> ... the uart driver is BROKEN.
>>
>> It simply locks up on the port after some period of time,
>> returning nothing.  I have found no way to reset the port
>> other than a reboot either ...
>>     
>
> Welcome to the distant past.  I'll be interested to see what
> the root cause turns out to be.
>
> I've seen the same symptoms on:
>
> * A Sun-3/50 running SunOS 4.1.1_U1, using ttyb;
>
> * A Sun Ultra 2 running (IIRC) Solaris 2.5,
>   using an Aurora multi-port S-Bus card;
>
> * A Sun Ultra 10, using an Aurora multi-port PCI card.
>
> The Suns were using Aurora drivers.  I was never able to get one of
> those systems' ttya or ttyb (using Sun drivers, of course) to hang
> that way.
I know. 

These sorts of problems remind me of the 90s.... and 80s.... :)

I've managed to put the fire out by rolling back to 7.1, but obviously
this isn't a long-term solution.  I'll get back on it over the weekend
and during Turkey Week - my "best guess" is that there's some sort of
problem with buffering somewhere.  Missed interrupts should not be a
factor on a PCI interface (as was occasionally an issue with the old ISA
cards) but the lack of a way to poke a port and reset it elevates
something like this from highly irritating to a serious issue.

Finding the problem isn't going to be easy either...

-- Karl