Session

s390 architecture machines contain Internal Shared Memory (ISM) devices. They provide for a method to share dedicated buffers between 2 devices, where the fabric guarantees that only the designated remote device can access this buffer. They were invented for and are used by the SMC-D protocol.

Since SMC is used on other architectures as well, an smc-loopback implementation has been added to the smc module, that can serve as an ISM-like fabric between network namespaces or containers. But smc-loopback is currently not fully represented in the device model.

There are proposals to implement a virtio version of ISM-like devices, that can be used to communicate between KVM guests.

On the other hand there is ongoing work on other exploiters e.g. a terminal server that accesses remote consoles on top of s390 ISM devices.

So this may be the right time to define a common class of such devices with common interfaces to their users. And maybe even find a better name than ISM-like devices?

In this talk, I want to provide an overview of the concept of such a class, its features and existing and future usecases.