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SubjectRe: DEVFSv50 and /dev/fb? (or /dev/fb/? ???)
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>>>>> "Richard" == Richard Gooch <Richard.Gooch@atnf.CSIRO.AU> writes:

>> I have not understood very well (I don' t know a lot about USB).

Richard> It seems that devices are hot-pluggable and that the order of
Richard> devices on the cable can change a lot. Using device serial
Richard> numbers (mapping them into devfs) seems to be a sane way of
Richard> dealing with the mess.

That's right. Devices are hot pluggable, swapable and
everything you could fear of in your nightmares :). The worst problem
is thus, keeping track of them. Tomorrow I may feel that the scanner
is better if I change it of position on the desk and also I can plug
it into the keyboard's hub, this way I'll have a hub port free on the
other hub for plugging the modem. The day after tomorrow my dad can
bring in his ZIP drive and I want to be able to refer to it as
"/dev/.../Dad's ZIP" (an example) if I have multiple zip drives or as
/dev/.../zip" if I only've got one. Adding a few persistence options,
which would make USB even more plug, play and forget, will allow this.

Back to the topic, tracking their positions is impossible, as
the kernel cannot guess my thoughts. But I can keep a record of their
serial number, or if no s/n available, how they look like (vendor and
device ids, revisions, characteristics ...) and have devfs presenting
them to you, letting it choose the major/minors for correct emulation;
I don't even care if they are on different controllers, they'll be
identified identically. If I had to track this by hand, I'd probably
go nuts ...

Linux-USB! http://peloncho.fis.ucm.es/~inaky/USB.html -
-
Inaky Perez Gonzalez -- PGP pubkey fingerprint -
inaky@peloncho.fis.ucm.es -- 8E 34 3A 62 64 99 E2 44 -
http://peloncho.fis.ucm.es/~inaky -- AD 7B 30 D9 DD FF 3E 4C -
--------------------------------- -- ----------------------- -
The loneliness of the long distance runner .....

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