I spent a little time today thinking about implementing a
uniform ioctl to extract the ieee1284 device ID data, but soon
realized that there is no device to do the ioctl on if no particular
parport client device driver has been loaded. So, I guess I'll
just live with the current /proc/sys/dev/parport/parportN/autoprobe
files (although I did end up generating a patch to clean up
ieee1284 device ID extraction in usb/printer.c, so the exercise was
Anyhow, here are some things that I would like to do, and
I would appreciate comments on them, as I would like to get the
kernel changes into Linus's releases if possible.
1. Change the current sysconf ieee1284 printer ID interface
to actually read the data when requested rather than storing it.
2. (Probably simultaneous with #1). Gut the printer ID
parsing code and have the interface just return the raw ID string.
As far as I can tell, nobody uses the parsed code. The parsing
could easily be done by a simple user level utility, and it just
makes ID string matching harder.
3. Define a MODULE_DEVICE_TABLE format for parport clients.
I think the format would simply be a null terminated string consisting
of regular expressions that a user level program could match to
autoload the module. For example, lp.c might have a declaration like
static char __initdata printer_ids =
4. Submit a patch to modutils so that depmod will generate
/lib/modules/<version>/modules.parptmap from any parpot
MODULE_DEVICE_TABLE entries. In this way, people will be able
to write new parport drivers and have their ID information work
without having to coordinate with the maintainers of some central
file of ID's.
5. Write "parptmodules", a simple application to implement the autoloading
from this information by reading /lib/modules/<version>/modules.parportmap
and /proc/sys/parport/ and printing the list of modules to load.
That way, Linux distributions would just do something like this in
some rc script:
for module in off $(parptmodules) ; do
modprobe -s -k $module
That would be enough to ensure that whatever modules were
needed would be loaded at boot time.
6. Add MODULE_DEVICE_TABLE entries to the current
users of partport_register_device if people will send me ID
strings (or they can the entries themselves):
7. One of these days, I would like to put together a mapping
of ieee1284 device ID's for printers to /etc/printcap and ghostscript
settings that would be regenerated every time a print job starts
printing (so you could switch printers), but that largely a separate
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