-----Original Message----- From: Jeremy Stanley fungi@yuggoth.org Sent: Monday, January 13, 2020 8:54 AM To: openstack-discuss@lists.openstack.org Subject: Re: [Cyborg][Ironic][Nova][Neutron][TripleO][Cinder] accelerators management
On 2020-01-13 07:16:30 -0800 (-0800), Dan Smith wrote: [...]
What does this matter though? If you're talking about firmware for an FPGA card, that's what you need to know in order to apply the correct firmware to it, independent of whatever application-level bitstream is going to go in there right?
[...]
Either way, I'm not sure how the firmware for accelerator cards is any different from the firmware for other devices on the system. Maybe the confusion is just that Cyborg does "programming" which seems similar to "updating firmware"?
[...]
FPGA configuration is a compiled binary blob written into non-volatile memory through a hardware interface. These similarities to firmware also result in many people actually calling it "firmware" even though, you're right, technically it's a mapping of gate interconnections and not really firmware in the conventional sense.
+1
I wouldn't be surprised, though, if there *are* NFV-related cases where the users of the virtual machines into which some network hardware is mapped need access to alter parts of, say, an interface controller's firmware. The Linux kernel has for years incorporated features to write or rewrite firmware and other microcode for certain devices at boot time for similar reasons, after all.
This aspect does come up for discussion a lot. Generally, operators and device vendors get alarmed at the prospect of letting a user/VNF/instance program an image/bitstream into a device directly -- we wouldn't know what image it is, etc. Cyborg doesn't support that. But Cyborg could program an image/bitstream on behalf of the user/VNF.
That said, the VNF or VM (in a non-networking context) can configure a device by reading from registers/DDR on the card or writing to them. They can be handled using standard access permissions, Linux capabilities, etc. For example, the VM may memory-map a region of the device's address space using the mmap system call, and that access can be controlled.
-- Jeremy Stanley
Regards, Sundar