[argyllcms] Re: Running dispcal stops usb card reader

On 16-02-2012 01:29, Graeme Gill wrote:

Ridouan Agarad wrote:


/proc to exclude ports already open by other processes.

Can you be more specific ?
First of all, this is specific to Linux, *BSD also has a similar procfs, but I don't have a BSD box on hand right now, so can't check... As for solaris, etc., that's way more limited anyway... Having said that and also that I do not the specifics of the VDR/softcam application, /proc has a list of open filehandles per process (/proc/<pid>/fd/<id>), where <id> is a symlink to the underlying device node (usually /dev/*). Knowing that and knowing you're about to open /dev/ttyXYZ, you could check if there's any process having an open handle to that same device node. If so, don't bother and continue.... 



As far as I can tell /proc/tty/ is Linux only, and
/proc/tty/driver is not accessible in user mode anyway.


Another option would be I guess is to allow (optional) specification
of either a device path in a conf file (bypassing the need to scan for
ports),

That's very user unfriendly though - I could expect anyone trying to
use a serial instrument to then have to ask how to do it.
Well, looking a bit closer at the documentation, I don't have argyllcms running (on Linux) and can't check, I guess using the '-c' parameter for e.g. dispcal would already allow one to achieve this, wouldn't it? 



In earlier versions I simply limited the number to about 4. Maybe
that's all I can do again.
Isn't /proc/devices maybe usable as an 'automatic' filter (if the file is available, that is) to filter out devices for which no driver is currently loaded (and thus not usable anyway)?

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