Re: 475/476/605 Serial "Reboot"
Olson, Greger J. - CLS/2 wrote:
>
> Last night I tried booting with different (2.0.33) kernels, extensions
> on/off, etc. with the same results:
> I can connect (pon), I can ping, I can open an FTP session, navigate remote
> directories, etc.,
> but any attempt to "get" a file causes an immediate reboot.
>
> Does anyone know just what happens when FTP/PPP starts sending/receiving
> files
> (as opposed to CD, LS, etc.)?
Your computer starts getting a huge number of bytes and tries to dump
them to disk while more are rushing in. Try listing some huge FTP directory
to
see if that triggers the same reboot. If so, it's just the data rate that's
getting too high to handle. Otherwise, it's probably a problem with data
being received while writing to disk.
> I'm beginning to suspect packet sizes/buffer overflows. I know the 475/LC
> serial hardware
> only supports 57600 (or so), a less than typical speed. During
> configuration I picked 38k.
To put it mildly, a Mac is a pathetic piece of hardware when it comes to
handling
disk I/O (without DMA) and serial I/O (with higher IRQ priority)
simultaneously.
Try reducing the serial rate to 19200 baud. I've tried data rates of 38400
on
a slower Mac (SE/30) with no ill effects after patching the serial driver
(originally, it would keep receiving data even after the driver internal
flip
buffer ran full, and trash tty data structures). That patch is in 2.0
kernels
for a year or so now, and should also be in 2.1. Seems the 475 behaves
different
there.
> Has anyone played around with misc. transmission settings? Are the serial
> drivers making
> unwarranted assumptions about serial capability?
No, they make unwarranted assumptions about interrupt priorities and bottom
half
latency. But that should only lead to dropped characters, not a reboot.
Someone with a 475 needs to debug this; I can give some pointers to start
from
but I'd prefer to take that discussion to the mac68k ML.
> I haven't tried printing yet - which uses the same serial hardware. Anyone
> had trouble
> printing with a 475?
Printing on a Mac uses LocalTalk protocol which isn't implemented. It uses
230k
baud, imagine the headache that causes if 38400 is already too much. This
isn't
to say it's impossible, it just would take a fair anount of work for no
apparent
profit...
Michael
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