Assuming no objections from Linus Torvalds, the now open Linux 6.15 merge window could introduce a brand new subsystem: fwctl.
The firmware control subsystem intends to help standardize and establish common rules among the growing number of drivers/hardware that expose a secure firmware interface to user-space.
Jason Gunthorpe of NVIDIA sent out the pull request today for introducing the fwctl subsystem to the Linux 6.15 kernel:
“fwctl is a new subsystem intended to bring some common rules and order to the growing pattern of exposing a secure FW interface directly to userspace. Unlike existing places like RDMA/DRM/VFIO/uacce that are exposing a device for datapath operations fwctl is focused on debugging, configuration and provisioning of the device. It will not have the necessary features like interrupt delivery to support a datapath.
This concept is similar to the long standing practice in the “HW” RAID space of having a device specific misc device to manage the RAID controller FW. fwctl generalizes this notion of a companion debug and management interface that goes along with a dataplane implemented in an appropriate subsystem.”
In addition to the initial fwctl subsystem code, there are three initial drivers for the subsystem: CXL, NVIDIA Mellanox MLX5, and AMD Pensando Smart NIC. The fwctl pull request explains:
“- CXL provides a vendor scheme for executing commands and a way to learn the ‘command effects’ (ie the security properties) of such commands. The fwctl driver allows access to these mechanism within the fwctl security model
– mlx5 is family of networking products, the driver supports all current Mellanox HW still receiving FW feature updates. This includes RDMA multiprotocol NICs like ConnectX and the Bluefield family of Smart NICs.
– AMD/Pensando Distributed Services card is a multi protocol Smart NIC with a multi PCI function design. fwctl works on the management PCI function following a ‘command effects’ model similar to CXL.”
If no last minute snafus, the fwctl subsystem should be merged in the coming days for the Linux 6.15 cycle.
