Re: udev-059 and default.hotplug script

[Kay Sievers <kay.sievers@vrfy.org>]

On Sun, Jul 03, 2005 at 06:26:29PM +0200, Marco d'Itri wrote:
> On Jul 03, Kay Sievers <kay.sievers@vrfy.org> wrote:
> 
> > But we need to walk through /sys/devices to catch devices there
> > for modules-load, ..., right? That is not handled by udevstart
> > currently.
> udevstart should walk /sys/bus/*/devices/ to support $MODALIAS (look at
> my modalias.rc).

Is there anything else than adding modalias support to udevstart to
replace what coldplug is doing today? But hey, this also only works
with 2.6.12 too. :)

> > On event replay you fire ~800 processes in a few seconds, while most of
> > these events are simple devices without any further processing. Tests showed
> > and my coworkers needed to convince me that doing this in-process is much
> > faster and you save some seconds bootup-time. (using udevstart does not have
> > this problem, cause it already does everything with only one process)
> Why not move the whole udev in udevd then, and make it fork and continue
> processing only when needed?

Sure, that's the plan and already works that way, but with kernels older
2.6.12, udevd would need to read the "dev" file in sysfs and the sysfs
files may arrive at any time later cause of bad sysfs-timing. So we
would need wait_for_sysfs in the daemon with stat() loops for concurrent
events in parallel compared to just use $MAJOR/$MINOR from the netlink event.
I don't say that this is impossible, but it definitely is a total mess.

With netlink, modalias and $MAJOR/$MINOR, only available after 2.6.11/2.6.12,
there is a good reason to drop old kernel-versions.

Thanks,
Kay


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