Re: [PATCH (stage1)] Rework module loading

[Bill Nottingham <notting redhat com>]

Jeremy Katz (katzj redhat com) said: 
> > - Ergo, we need to either duplicate all the alias handling, sysfs
> > walking, etc. in anaconda...
> > - Or, we use the system modprobe and udev coldplug. (That is what
> > this implements.)
> 
> jcm had said he was going to get a libmodprobe, but I suspect that's not
> likely to happen in a timely fashion :-/   

Even with that, you'd still need code to walk sysfs. Not that that's *that*
complicated, but it is duplication.

> > - Passing module options on the commandline is still supported
> 
> Given that we write out /etc/modprobe.d/anaconda, does it then make
> sense to switch to copying that over to the installed system rather than
> the fun around /tmp/modprobe.conf?

Intended but forgot to implement - yes, that would be the right
thing to do.

> > - blacklist=<foo> is now supported, to blacklist automatic loading of
> > a particular module
> 
> How does blacklisting interact with manually selecting the same module?

blacklisting means 'ignore any aliases for this module'. So it will
never get loaded by net-pf-<whatever> or pci:<whatever> aliases, but
can still be loaded directly by hand.

> > - nofirewire, nousb, etc. are ignored. The only noXX handled is
> > 'noprobe', which disables udev coldplug entirely.
> 
> Having some of these back would be really useful -- the fact that we can
> just not probe a specific problematic subsystem is regularly more useful
> than having to push people through loading every driver manually.
> Especially when you have a USB keyboard...

The simple way to do this would be to boot with blacklist=firewire-ohci,
or similar. If we want to automatically map a couple of old common options
to this, we could, but I don't think it's the right way to handle this
for new things. (After all, fix the kernel!).

> > - Driver disks are not modified to the new tree layout. Basically,
> > they should now be extracted and copied to
> > /lib/modules/$(whatever)/updates/. Some tweaks with depmod may be
> > necessary to get the aliases in the right place.
> 
> Does this mean we'll need to run depmod at installer runtime?  Or can we
> just concatenate the alias and deps files?

Concatenation should work for modules.alias. Not 100% about modules.dep;
will need to test/bug jcm.

> > Size concerns:
> > Before: 7.2MB
> > After: 8.6MB 
> 
> What's the memory overhead of not having the modules compressed "on
> disk"?  du -sh of the uncompressed initramfs vs the old should give a
> reasonable idea here. 

F8: 9.4MB
This: 29.7MB

17.3MB of the 20.3MB difference is in the modules tree.

Bill