On Sun, 11 Feb 2007 07:47:29 -0500 Richard Freeman <[EMAIL PROTECTED]> wrote:
> -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > Hmm - after a reboot yesterday the order of my various /dev/video#'s > have changed. I'm guessing this was related to the recent baselayout > update (one of those reasons I always reboot within a few days after a > baselayout change - I want to make sure I can reboot at all lest the > system be down while I'm out of town). Or maybe it was due to this > monthly udev update cron job that seems to get triggered nowadays. > > Any ideas what might cause this to happen? > > It took a while to figure out what was happening - I run myth and all > it knew is that the device it was trying to access wasn't initializing > correctly. I figured the card had some issue, but it eventually > turned out that I was addressing the wrong card and doing it in the > wrong way. > > This seems to be one of those potential unix achilles-heels. Devices > just have those generic /dev/devicename mknods, but there isn't > anything that uniquely identifies a specific device. If these mknods > change order then everything gets confused. I guess a solution would > be to assign some kind of GUID to each device and use that to address > them - but that of course gets rid of the elegance of the > everything-is-a-file philosophy. Maybe create two links to the > device - one with a classic name, and another which is a GUID-based > filename, and software can use either one. You can usually use udev to rename the devices (or to provide alternative names). This is commonly done for network interfaces, for example. > I had a similar issue with a pair of USB serial ports I bought. Now, > this is probably not linux's fault - but the devices had NO uniquely > identifying info embedded in them as far as I could tell. So, I was > very nervous about them switching around their mknods after reboots, > after moving them around, etc. In the end I edited the udev > configuration to create a second mknod for each device that was > associated with the specific USB port they were plugged into (so much > for plug-and-play). My understanding is that windows has the same > problem with these sorts of devices - they work real great until you > have a bunch of them. > > Does anybody know if a generic solution exists to these sorts of > problems in linux, or how to mitigate these sorts of issues? With the > increased usage of USB I'd think that situations like this will only > come up more often... > -----BEGIN PGP SIGNATURE----- > Version: GnuPG v1.4.6 (GNU/Linux) > Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org > > iD8DBQFFzxBhG4/rWKZmVWkRAjDOAKDP4f+KaU/a+X7Cz79N9MGPLugX5QCgyUEp > 9lA35LPJOpIx0D8ty4XvVyk= > =tvvJ > -----END PGP SIGNATURE----- -- Kevin F. Quinn
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