Re: [RFC net-next 0/7] Provide an ism layer

Alexandra Winter
2025-01-17T15:38:46Z

On 17.01.25 16:06, Andrew Lunn wrote:
>> With this proposal ism_loopback is just another ism device and SMC-D will
>> handle removal just like ism_client.remove(ism_dev) of other ism devices.
>
> In Linux terminology, a device is something which has a struct device,
> and a device lives on some sort of bus, even if it is a virtual
> bus. Will ISM devices properly fit into the Linux device driver model?
>
> Andrew
>

ism_vpci lives on a pci bus (zpci flavor) today. The fact that it is not
backed by a real hardware PCI slot, but emulated by s390 firmware is not
visible to Linux.

In the first proposal, ism_lo lived in on a virtual bus, afaiu. I liked
that. In the current stage 1 implementation that is currently upstream,
it is not visible in sysfs :-(

ism_dev is a bit modeled after net_device. So it is contains a pointer
to a struct device, but it is not the device itself.

I have to admit that the sysfs details are a bit confusing to me,
so I wanted to discuss them first before adding them to the RFC.
But I tried to bring all the prereqs in place.