Re: udev - easy setup ?
On Tuesday 02 August 2005 18:07, Uwe Dippel <udippel@uniten.edu.my>
(<[🔎] pan.2005.08.03.00.07.53.344090@uniten.edu.my>) wrote:
> On Tue, 02 Aug 2005 09:37:36 -0600, Jules Dubois wrote
>
>> BUS="usb", SYSFS{product}="NEC USB UF000x", NAME="%k",
>> SYMLINK="usb-floppy"
>>
>> BUS="usb", SYSFS{manufacturer}="KINGSTON ",
>> SYSFS{product}="DATA TRAVELER", NAME="%k", SYMLINK="usbhd%n"
>>
> Though, as you pointed out (and I had pointed out in the first post): I am
> not interested to recognise this particular NEC floppy or a Kingston
> thumb drive.
I read and/or skimmed parts of the USB mass storage class (MSC)
specification [1], and my interpretation is that MSC specs do not directly
distinguish between device "types" (i.e., HDD, FDD, thumb drive, etc.).
rather, they specify things like interfaces, the sort of thing a driver
needs to know; they're all mass-storage devices.
>> Since it looks like an interesting problem, I'll look into it further,
>> if you like.
>
> Yes, please, for sure !
Here is a set of rules, based on "bInterfaceProtocol" and "CBI", which may
work with the two devices above. If I understand correctly, it will name
all USB "hard" drives (thumb drives and mechanical drives) as 'usb-hd?'.
BUS="usb", DRIVER="usb-storage", SYSFS{bInterfaceProtocol}="0[01]",
KERNEL="sd*", NAME="%k", SYMLINK="usb-floppy%n"
BUS="usb", DRIVER="usb-storage", SYSFS{bInterfaceProtocol}="50",
KERNEL="sd*", NAME="%k", SYMLINK="usb-hd%n"
However, the MSC [1] (p. 7) says
The USB Mass Storage Class Control/Bulk/Interrupt (CBI) Transport
specification (Protocol codes 0x00 and 0x01) is approved for use
only with full-speed floppy disk drives. CBI shall not be used in
high-speed capable devices, or in devices other than floppy disk
drives. Use of CBI for /any/ new design is discouraged.
Floppy disks which do not use CBI will be improperly named with the rules
above.
While I haven't exhausted udev's features, including RUN and RESULT, I don't
know how I'd use them. If it were me and I didn't have a large number of
devices to support, I think I'd use rules with keys like "manufacturer" and
"product", adding new rules as I encountered new devices. It would be
tedious, but it will work.
[1] "Universal Serial Bus Mass Storage Class Specification Overview".
USB Implmentors Forum.
http://www.usb.org/developers/devclass_docs/usb_msc_overview_1.2.pdf
[Note that the vermin at USB-IF have copy protected their documentation
and that I have been reduced to retyping quotations.]
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