Re: Documentation for sysfs, hotplug, and firmware loading.

From: Greg KH
Date: Fri Jul 20 2007 - 20:44:51 EST

On Fri, Jul 20, 2007 at 08:21:39PM -0400, Rob Landley wrote:
> Ok, back up. /sys/devices does not contain all the information necessary to
> populate /dev, because it hasn't got things like
> ramdisks, /dev/zero, /dev/console which are THERE in sysfs, which may or may
> not be supported by the kernel (the kernel might have ramdisk support, might
> not).

Welcome to 2007:

$ ls /sys/devices/virtual/mem/
full kmem kmsg mem null port random urandom zero
$ ls /sys/devices/virtual/tty/
console tty12 tty19 tty25 tty31 tty38 tty44 tty50 tty57 tty63
ptmx tty13 tty2 tty26 tty32 tty39 tty45 tty51 tty58 tty7
tty tty14 tty20 tty27 tty33 tty4 tty46 tty52 tty59 tty8
tty0 tty15 tty21 tty28 tty34 tty40 tty47 tty53 tty6 tty9
tty1 tty16 tty22 tty29 tty35 tty41 tty48 tty54 tty60
tty10 tty17 tty23 tty3 tty36 tty42 tty49 tty55 tty61
tty11 tty18 tty24 tty30 tty37 tty43 tty5 tty56 tty62

I suggest you take a close look at the kernel before making statements
like the above :)

> These things could also, in future, have their major and minor numbers
> dynamically (even randomly) assigned. That's been discussed on this list.

I tried that once, it will require some core api kernel changes and a
lot of infrastrucure work to get that to work properly. Not that it
will never happen in the future, but it's just not a trivial change at
the moment...


greg k-h
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