Re: Q: acpi-cpufreq module auto-loading after processor driver change

["Rafael J. Wysocki" <rjw@sisk.pl>]

On Thursday, June 06, 2013 11:51:54 PM Rafael J. Wysocki wrote:
> On Thursday, June 06, 2013 01:24:19 PM Greg Kroah-Hartman wrote:
> > On Thu, May 30, 2013 at 11:38:37PM +0200, Rafael J. Wysocki wrote:
> > > Hi Greg,
> > > 
> > > I've noticed during recent testing that with this commit applied:
> > > 
> > > http://git.kernel.org/cgit/linux/kernel/git/rafael/linux-pm.git/commit/?h=acpi-hotplug&id=ac212b6980d8d5eda705864fc5a8ecddc6d6eacc
> > > 
> > > on my openSUSE (and Tubmbleweed) installations I need to modify
> > > /etc/sysconfig/kernel to make mkinitrd put the acpi-cpufreq module into the
> > > initramfs or otherwise it won't be loaded automatically.
> > > 
> > > I think I understand why it needs to be present in the initramfs along the
> > > processor module for the automatic loading to work (acpi_processor_load_module()
> > > seems to need that), but before the above commit it wasn't necessary to make
> > > any changes to /etc/sysconfig/kernel and acpi-cpufreq was loaded automatically
> > > anyway.
> > > 
> > > Unfortunately, my experience with udev and related things is kind of limited
> > > and I have no idea what exactly makes the difference.  Can you please have a
> > > look and help me understand that?
> > 
> > Don't you need a MODULE_DEVICE_TABLE() macro in that module somewhere so
> > that udev and the like know to load it when it sees the hardware?
> 
> Well, that was my first thought about that, but there is one already and my
> commit hasn't changed it. :-)

My understanding of this is that on x86 (which is the case here)
topology_init() calls arch_register_cpu() for all available CPUs which
calls register_cpu() and that causes the uevent to be emitted through
device_register().  But then, the commit above doesn't change that (at least
I don't see how).

Thanks,
Rafael


-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.