*BSD News Article 81568


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From: j@uriah.heep.sax.de (J Wunsch)
Newsgroups: comp.unix.bsd.freebsd.misc
Subject: Re: internal modem sio question
Date: 25 Oct 1996 21:20:11 GMT
Organization: Private BSD site, Dresden
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References: <3266E9E8.5D0A@sprynet.com> <549ief$o6m@library.airnews.net>
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Reply-To: joerg_wunsch@uriah.heep.sax.de (Joerg Wunsch)
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dblizzar@sprynet.com (Dave Blizzard) wrote:

> The problem is that FreeBSD doesn't even see the modem's serial
> interface sio2.  This seems to be a modem hardware problem as Jordan
> says " some modems just emulate the 16550 uart"

Almost all internal modems just emulate the 16550.  They probably
emulate it with an ASIC that has no real `registers' like a genuine
UART, but instead runs some sort of microprogram to respond to the ISA
bus commands.  This often takes a microsecond or two, much more than a
real UART needs.

You can cause the sio driver to be more verbose about its doing (in
particular at the device probe time) by specifying the flag 0x80 for
your sio2 (boot with -c, and modify the `flags' field).  This way,
you'll see which probes fail.  Use this info to walk into the file
/sys/i386/isa/sio.c, look for the function sioprobe() there, and see
whether it's possible to modify the timing for the probe that fails
for you -- the failed probes are being registered in the array
failures[] there.


Btw: ``Jordan says''... (The following is not meant personally against
you, Dave, but rather a general note, also based on own experience.)

It's really not the most desirable behaviour to approach the
developers directly for this kind of `generic' questions where quite a
few more people will be able to answer it.  Unless you know the
special fields of each of the various developers, you often won't even
reach the most knowledgable person for just your problem.  So, better
stick with the mailinglist freebsd-questions@freebsd.org, or this
newsgroup here.  There are more people around anyway, so it's not
unlikely that the response time is shorter at all, and you help taking
the load off the most busiest people.

To make it clear, nobody of us minds people talking to any developer
directly, after all, that's one of the advantages of an open and
transparent software development organization.  However, noone of us
has an infinite amount of time available, and you certainly also
expect us doing further development... :)  So, use the direct approach
only if you are convinced that this is a problem nobody else than your
intended addressee could solve.

-- 
cheers, J"org

joerg_wunsch@uriah.heep.sax.de -- http://www.sax.de/~joerg/ -- NIC: JW11-RIPE
Never trust an operating system you don't have sources for. ;-)