Date: Sun, 08 Jun 2008 10:16:26 -0400 From: Chuck Robey <chuckr@telenix.org> To: ticso@cicely.de Cc: FreeBSD-Hackers <freebsd-hackers@freebsd.org> Subject: Re: number of /dev/usb nodes Message-ID: <484BE9BA.5040308@telenix.org> In-Reply-To: <20080608134227.GM71712@cicely7.cicely.de> References: <484AC2F1.1000806@telenix.org> <20080608134227.GM71712@cicely7.cicely.de>
next in thread | previous in thread | raw e-mail | index | archive | help
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Bernd Walter wrote: > On Sat, Jun 07, 2008 at 01:18:41PM -0400, Chuck Robey wrote: >> -----BEGIN PGP SIGNED MESSAGE----- >> Hash: SHA1 >> >> I can't seem to find how many /dev/usbN bus devices there can be. I'm writing >> some code that scans them all looking for anything that has my device, but I >> while I know to start at usb0, just how high do I go? There seem to be 128 >> device minors, is that the number? (from dev/usb/usb.h) > > There shouldn't be a limit anymore. > I can't see any definition of 128 in usb.h that limits the number of > busses. > The major/minor differenciation is long time ago. > You must be looking at old code. > I was trying to find a good way to do scanning, whjen I create the files like /dev/usb0, how far to go in my loop? Does the lowest available device always get created? That would imply that as soon as I began to get "No such device" errors, I could stop iterating. If the rules for picking device filenames are pretty loose, then I could (for instance) stop scanning, say, 4 numbers past the first "No such device" returnee. Any idea on this? I didn't see this i nthe code, but I just need some sane limit on what filenames to scan about in. I look for item info, and if the usb vendor and prodict look friendly, I just snag the filename involved, and use that. Like, a scan of the usb1 bus might yield me a uhid0 which might be my meat, whereupon I coulld drop the usb1 open, and replace it with a uhid0 open. There's more than 1 place that my devices could show, depending on the user's kernel devices. I just want to have some sane limit on how many usb buses I open for my scanning. -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.4 (FreeBSD) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFIS+m6z62J6PPcoOkRAgBoAJ0XYYfUat/fJDChSybpNtFzCwUr9ACdGxNf UoCeHzvriXfQ+bj5LDxE8vA= =sTcT -----END PGP SIGNATURE-----
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?484BE9BA.5040308>