[SunRescue] Help with IPC serial ports...

[James Lockwood]

On Tue, 28 Dec 1999, Kurt Mosiejczuk wrote:

> This is where the problems are.  Anything greater than 9600 baud
> ends up with serial input overruns.  I even recompiled the kernel to
> take out the cruft I don't need.  Still problems.
> 
> So, I started searching the net for help.  Seems that I may just be out
> of luck.  Apparently the zs8530s on almost all sparcs have just a 3-byte
> FIFO, no DMA, and require LOTS of CPU intervention.  After all this, I'm 
> amazed my IPX had no problems at 38400.

I've got three words for you, and they're probably not what you want to
here:

"Run SunOS/Solaris".

The zs serial port driver in SunOS 4/5 can sustain 38400bps on an IPC
class machine with no problem, and 76800bps is doable on an IPX or faster.
*BSD and Linux can't do this on the same hardware.  For most things they
are more lightweight and perform better on low-end hardware, but they are
lacking in zs serial port performance.

I used a SS1+ as my dialup PPP gateway at 38400bps for over 2 years.  No
overruns or other problems.  Ran both SunOS 4.1.3u1 and Solaris 2.4, along
with ipfilter, the Harvest Cache and a boatload of other daemons.  For a
NAT router, you can fit the OS and everything else on a 100MB disk with a
bit of work, and 24MB RAM is sufficient.  16MB would work if you went with
SunOS 4, but given the lack of support and number of patches I wouldn't
recommend it.

-James