On Mon, Jan 25, 2021 at 11:34:49AM -0800, Edwin Peer wrote: > What do these amount to in practice? Presumably config space is backed > by normal memory controlled by firmware. Do VF's need to expose ECAM? > Also, don't MSI tables come out of the BAR budget? Is the required BAR > space necessarily more than any other addressable unit that can be > delegated to a SF?
Every writable data mandated by the PCI spec requires very expensive on-die SRAM to store it. We've seen Intel drivers that show their SIOV ADIs don't even have a register file and the only PCI presence is just a write-only doorbell page in the BAR. It is hard to argue a write-only register in a BAR page vs all the SRIOV trappings when it comes to HW cost. Jason
