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Re: [hylafax-users] HylaFAX 4.2.1-23 and Fedora Core 3

* Terry D. Boldt <fastsnip-frnds1@xxxxxxxxx> [050829 17:48]:

> As a theoretical physicist, I have always noticed that actual practice has a 
> rather rude way of upsetting theory. In this case, both kppp and 
> HylaFAX/faxgetty refer to/use /dev/ttyS0. 

Yup - But as someone with much practical HylaFAX experience, I *know*
that faxgetty can co-exist with other software using the same serial

The conditions for this to happen are:

1) Both applications must be able to speak to the device (so the system
   level permissions must be correct)
2) They must "arbitrate" between themselves who can/can't control the
   device at any particular point in time.

HylaFAX has both of these bases covered, and provided the "other"
application can cover these as well, things can co-exists together.

#1 - Device permissions
     This is probably covered fine - UNIX tradition has that "uucp"
     users/groups have rw permissions to the serial devices.  faxgetty
     has a "DeviceMode" config option if you need to have even more lax
     permissions (like even rw-rw-rw-)

#2 - Device arbitration/locking
     As long as all programs "lock" the device in a consistent manner,
     only 1 program has control of the device at a time.  Again, HylaFAX
     supports both the UNIX/SVR4 traditions of binary/ASCII name/number
     lock files, and locations.  These can all be controlled with the
     UUCPLock* options.

So, a checklist for making faxgetty cooperate with other devices:

1) Make sure they are using the same device node (both, /dev/ttySX, or
both /dev/ttyLT0).  This needs to be true, or the locking just won't
work.  If they are using different device nodes (which may point to the
same physical device), the both programs can have exlusive access to
their device node, but be hammering on the same device at the same time.

2) Make sure that the locking is consistent between all the programs.
In HylaFAX, this can be configured by the UUCPLock* config options.  For
kppp, you will have to figure out what type of locking it's doing, and
then make both kppp and hylafax use the same locking mechanism.

Aidan Van Dyk                                             aidan@xxxxxxxx
Senior Software Developer                          +1 215 438-4638 x8103
iFAX Solutions, Inc.                                http://www.ifax.com/

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