[PATCH] Bug #975

Natanael Copa natanael.copa at gmail.com
Tue Aug 22 21:28:19 UTC 2006


On Tue, 2006-08-22 at 22:11 +0200, Yann E. MORIN wrote:
> Natanael,
> All,
> 
> On Tuesday 22 August 2006 003, Natanael Copa wrote:
> > On Mon, 2006-08-21 at 23:10 +0200, Yann E. MORIN wrote:
> > > Bug #975 is about udev spawning multiple modprobes at cold-plugging-time (that
> > > is boot time). The problem occurs when two devices require the same module
> > > (eg. two or more same PCI cards, two or more same USB keys, etc...).
> > Does this affect mdev too? mdev -s?
> 
> I don't know, I haven't yet used mdev in BusyBox... :-/

I use it that's why I'm asking.

> Rob, could you enlighten us on this topic, please?
> 
> > How do you coldplug? 
> 
> My Debian etch simply uses a combination of udevtrigger (launches the coldplug
> handling) followed by a udevsettle (waits for the event queue to be empty).

What version of kernel? I use mdev -s and then 
  find /sys -name modalias
 and then load the modalias (works great thanks to your previous
patches). requires somewhat newer kernel (2.6.15++ i think)
mdev creates the /dev entries.

That way I manage to detect all hardware that udev coldplug did.

> > Would it affect if you coldplug like this?:
> > find /sys -name uevent | while read i ; do 
> >   echo "add" > $if ;
> Maybe: s/\$if/\$i/;
yes ofcourse... :-)
> > done
> 
> Don't know, I haven't got any BusyBox system doing coldplug right now...

thats basicly what udev trigger does.
while pidof mdev ; sleep .. something do the same as udevsettle. Ifound
out i don't need to do a full cold plug (trigger hotplug events). Its
enough to find modaliases and load those.

I switched from udev to busybox mdev not long ago. It is simplier but
you dont need to have the udevd running all the time. udev are more than
100Kb bigger but it only adds a very few additional features. mdev is
fast.

If you want to try mdev in real life, download my alpine linux projcet.
Its a modular "livecd" where packages are installed into tmpfs during
boot.

http://tanael.org/alpine/v1.3/alpine-1.3.7-i386.iso (130MB ++)

usb versions (.zip or tar.gz) and md5 sums are found here:
http://tanael.org/alpine/v1.3

Its big because there are over 250 packages included.

Try it on different hardware. mdev -s and find modaliases does a very
good job.


> Again: Rob?
> 
> Regards,
> Yann E. MORIN.
> 




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