Re: [ANNOUNCE] hotplug-ng 002 release

Greg KH
2005-05-11T05:36:55Z

On Tue, May 10, 2005 at 11:51:04PM +0200, Per Liden wrote:
> On Mon, 9 May 2005, Greg KH wrote:
>
> > On Mon, May 09, 2005 at 12:52:02AM +0200, Per Liden wrote:
> > > On Fri, 6 May 2005, Greg KH wrote:
> > >
> > > [...]
> > > > Now, with the 2.6.12-rc3 kernel, and a patch for module-init-tools, the
> > > > USB hotplug program can be written with a simple one line shell script:
> > > > modprobe $MODALIAS
> > >
> > > Nice, but why not just convert all this to a call to
> > > request_module($MODALIAS)? Seems to me like the natural thing to do.
> >
> > Because that's not the only thing that the hotplug event causes to
> > happen. It's easier to have userspace decide what to do with this
> > instead.
>
> Sure, the hotplug event could still be issued so that userspace could do
> magic things when it wants to (load firmware or whatever), but since the
> kernel already has all the infrastructure in place to load modules on
> demand, and it's used all over the place, it doesn't make sense to use a
> completely different approach here.

Well, do you really want your kernel to be creating 2 userspace programs
for every device in sysfs that is created? Remember, we can't just not
emit that hotplug event, too many programs need it....

> Also, since most people never need to do anything except modprobe, they
> can still have a working system without any scripts what so ever... again
> just like normal on demand module loading.

Lots of programs do lots of stuff other than modprobe on hotplug events.
Look at HAL for just one example.

thanks,

greg k-h