On Saturday 26 December 2020 at 19:04:51, Didier Kryn wrote:

> I guess it's historical: historically there was only character devices and
> block devices, and no provision for other categories, and maybe no provision
> in the bitfields which qualify the associated special files.

Sounds entirely plausible. I, too, have long wondered why ethX devices were
never represented under /dev

> These device special files are used in particular to write to and read from
> and I think nobody wants this to happen with network devices. AFAIU, there
> are a lot of devices which don't show up in /dev, like all the intermediate
> devices, the ones which handle USB, SCSI, SATA, PCI.

Hm...

/dev/ttyUSBX
/dev/sdX
/dev/srX
/dev/hdX

I can't really think of a sensible category for PCI, since it's not so much a
family of devices as just a way of plugging things in. I mean, we never had
/dev entries for ISA, VESA, AGP (and probably many more I don't think of right
now), so why should the PC bus appear in /dev?

What's important is the thing that's plugged in to PCI, and that appears as
/dev/lpX, /dev/ttyX, /dev/sdX, etc.

I also see no reason to list a USB hub, or a PCI bus, as a "device". It's not
like anything in userspace needs to talk to it, and that's what /dev is for,
yes?


Antony.

--
Pavlov is in the pub enjoying a pint.
The barman rings for last orders, and Pavlov jumps up exclaiming "Damn! I
forgot to feed the dog!"

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