[systemd-devel] how to bind to other drivers using systemd

[Panu Matilainen]

On 10/13/2015 03:28 PM, Harald Hoyer wrote:
> On 13.10.2015 14:08, Panu Matilainen wrote:
>> On 09/30/2015 08:43 PM, Flavio Leitner wrote:
>>> On Tue, Sep 29, 2015 at 12:30:54AM +0300, Mantas Mikulėnas wrote:
>>>> I wonder if this could be handled with a generic Type=oneshot,
>>>> ExecStart=driverctl bind foo...
>>>
>>> Could you elaborate more on that?
>>>
>>> If driverctl is an utility, we could use scripts, yeah.  The issue
>>> is how to identify the device. We probably would need some sort
>>> matching mechanism like udev does.
>>
>> Since the silence is deafening, and since its usually easier to poke holes in
>> something concrete no matter how incomplete and/or broken, here's a beginning
>> of an approach to alternative driver assignment in the udev realm:
>> http://laiskiainen.org/udev/driverctl/
>>
>> # <copy/patch the bits to their places>
>> # echo vfio-pci > /etc/driverctl.d/0000:01:00.0
>> # echo 1 > /sys/bus/pci/devices/0000:01:00.0/remove
>> # echo 1 > /sys/bus/pci/rescan
>>
>> ...and there you go, udev vfio-pci is forced for that device on the rescan, and
>> a real hotplug is handled similarly.
>>
>> Since normally the device probing occurs early in the boot, these things also
>> need to go to initramfs so a dracut module/patch is needed, and dracut needs to
>> be run after adding devices here, ie
>>
>> # echo vfio-pci > /etc/driverctl.d/0000:01:00.0
>> # dracut -f
>> # reboot
>
> If both kernel modules are already in the initramfs, you don't have to do this.

'dracut -f' is necessary to get any new/changed/removed 
/etc/driverctl.d/ bits into the initramfs though.

I had not considered the modules question at all, which is of course 
another valid concern, these non-default drivers might well not be in 
the initramfs by default.

Thanks,

	- Panu -