Re: [linux-usb] Re: USB device allocation

Khimenko Victor (khim@sch57.msk.ru)
Sat, 9 Oct 1999 13:16:22 +0400 (MSD)


In <E11ZiN6-0004gG-00@the-village.bc.nu> Alan Cox (alan@lxorguk.ukuu.org.uk) wrote:
>> > RJ> The Unix-like kernel knows only major/minor device numbers, not names.
>> > Which POSIX standard says how unix-like kernel acts inside ???
>>
>> I'm beginning to wonder why we're still fumbling around with the
>> major/minor concept. Is there any compelling reason for it other than
>> "thats the way we've always done it since 1970's, and 640k is enough ram
>> for anyone"?

AC> You need a permanent on disk device key for the system.

Correct.

AC> That basically means either a name or number in the inode.

Correct.

AC> A number is obviously somewhat easier.

Wrong. Configuration files for programs uses names (like "/dev/ttyS0" or
wahtever) anyway. So you have NO choice: you use names. Then you can translate
it to major/minor numbers and then kernel will translate major/minor number in
device address (old way) or you can translate device name straight to device
address (devfs way). Why old way is preferrable ? This is the question.

AC> major/minor is a very clean and neat idea - we might want 32bits of it sure

They are clean and neat ONLY if we agree that intermediate step
(device name->major/minor->driver address) is needed. And I can not understood
why it's needed.

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