PUC Serial I/O problem - copy of gnats-filed bug report (as discussed previously)

[Karl Denninger]

Karl Denninger wrote:
> Jeremy Chadwick wrote:
>   
>> On Fri, Nov 27, 2009 at 12:54:17PM -0600, Karl Denninger wrote:
>>   
>>     
>>> For what its worth, USB-based serial adapters also fail in the same way,
>>> but faster (they have NEVER been reliable in this regard, and this
>>> hasn't improved)
>>>     
>>>       
>> There must be a regression of some kind, given that some FreeBSD
>> developers have stated in the past that FTDI-based USB serial adapters
>> work great:
>>
>> http://lists.freebsd.org/pipermail/freebsd-stable/2008-March/041615.html
>>
>> Original thread:
>>
>> http://lists.freebsd.org/pipermail/freebsd-stable/2008-March/041610.html
>>   
>>     
> I don't know where "works great" has come from.  Certainly not my
> experience in "heavy" use.
>
> For non-modem-control heavy use, it works ok.  I use an 8-port fanout on
> 7.x to drive process control and it's stable.
>
> However, for heavy modem use (e.g. Hylafax) it has NEVER been stable -
> although in 8.x it won't even manage to send ONE 10-page fax most of the
> time, where under 7.x it would randomly fail in that use.  Then again
> the puc() driver based serial I/O was completely stable under 7.x and
> now, with the "new architecture" it will get one or two jobs through it
> before it blows up.
>
> -- Karl
>   
FYI I downgraded back to 7.2-STABLE (it was a bit hairy but I got it to
work after a small amount of screwing around) via sources
and again the machine and those serial ports are 100% stable with the
old driver infrastructure.

The uart() infrastructure in 8.x has to be considered broken and
unusable for modems at this point folks.  I recognize that nobody
flagged it until just before the release (I hadn't tried it until RC2,
and thus didn't know) but this is a literal dagger in the heart of
anyone who needs to put an actual modem on an 8.x box using the common
cards out there, and I assume it will bite just as hard for things like
a dial-in console as it will for a fax server.

-- Karl