Re: [PATCH v2 0/2] firmware: arm_scmi: Ensure automatic module loading

[Brian Masney]

Hi Hans,

On Thu, Jul 09, 2026 at 03:22:29PM +0200, Hans de Goede wrote:
> On 9-Jul-26 12:10, Sudeep Holla wrote:
> > On Thu, Jun 18, 2026 at 10:31:12PM +0200, Hans de Goede wrote:
> >> On 18-Jun-26 17:56, Bjorn Andersson wrote:
> >>> SCMI drivers such as the Arm SCMI CPUfreq driver are allowed to built as
> >>> modules, but they are then not automatically loaded. Rework the SCMI
> >>> device table alias support to make modpost consume the information from
> >>> MODULE_DEVICE_TABLE(scmi, ...) and allow drivers to be loaded based on
> >>> this information, if known. Also add a protocol-based alias to also
> >>> trigger driver loading when only the SCMI protocol id is known.
> >>>
> >>> Signed-off-by: Bjorn Andersson <bjorn.andersson@xxxxxxxxxxxxxxxx>
> >>
> >> So I just gave this a test spin and unfortunately it does not work.
> >>
> >> The problem with Fedora's kernel-config / setup is that the
> >> request_module() from patch 2/2 runs from the initramfs, but
> >> the scmi_cpufreq module is only available in the rootfs.
> >>
> >> It does work if I explictly add the scmi_cpufreq module to
> >> the initramfs, then it does get autoloaded.
> >>
> >> We really need some place to put a uevent sysfs attr which then
> >> gets replayed when udev is restarted from the rootfs and then
> >> re-reads all the uevent files as part of its coldplug
> >> enumeration.
> >>
> > 
> > I don't have much knowledge on uevent to provide any suggestions/help.
> > But isn't this a generic requirement ? I mean you could have modules
> > install on the rootfs and not all of them are packed in initramfs ?
> > Just wondering if that works for other modules, we can examine how
> > do they work and what are we missing ?
> 
> scmi is special because the actual devices under /sys/bus/scmi/devices
> only get created when the module with the driver is loaded because
> of some funtion/id mapping requiring info from the driver.
> 
> Patch 2/2 tries to work around this by loading all scmi drivers matching
> the scmi protocol which is known at bus enumeration time, but this only
> works if the actual scmi driver is in the initramfs because this done
> through directly calling modprobe() from the kernel which does not
> get "replayed" when switching to the real rootfs.

Should the SCMI drivers be added to the dracut module here?

https://github.com/dracut-ng/dracut/blob/main/modules.d/70kernel-modules/module-setup.sh#L73

A few years ago we had to add the interconnect drivers to the list for
Fedora.

Brian