Re: number of /dev/usb nodes
- From: Bernd Walter <ticso@xxxxxxxxxxxxxxxxx>
- Date: Sun, 8 Jun 2008 17:50:17 +0200
On Sun, Jun 08, 2008 at 10:16:26AM -0400, Chuck Robey wrote:
-----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.
This wouldn't work if a USB controller is remove - e.g. a pulling a
cardbus card.
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.
I never had to deal with this, since writing a USB driver is simple and
as a driver you get informed for each new device.
No need to scan the busses yourself.
But I would say that the most reliable way is to just scan /dev/ for
usb...
--
B.Walter <bernd@xxxxxxx> http://www.bwct.de
Modbus/TCP Ethernet I/O Baugruppen, ARM basierte FreeBSD Rechner uvm.
_______________________________________________
freebsd-hackers@xxxxxxxxxxx mailing list
http://lists.freebsd.org/mailman/listinfo/freebsd-hackers
To unsubscribe, send any mail to "freebsd-hackers-unsubscribe@xxxxxxxxxxx"
- Follow-Ups:
- Re: number of /dev/usb nodes
- From: Chuck Robey
- Re: number of /dev/usb nodes
- References:
- number of /dev/usb nodes
- From: Chuck Robey
- Re: number of /dev/usb nodes
- From: Bernd Walter
- Re: number of /dev/usb nodes
- From: Chuck Robey
- number of /dev/usb nodes
- Prev by Date: Re: Kerberized CIFS client?
- Next by Date: Re: number of /dev/usb nodes
- Previous by thread: Re: number of /dev/usb nodes
- Next by thread: Re: number of /dev/usb nodes
- Index(es):
Relevant Pages
|
