On Wed, Jul 13, 2022 at 11:48:04AM -0700, Jakub Kicinski wrote: > On Wed, 13 Jul 2022 09:40:01 +0100 Martin Habets wrote: > > > So it's switching between ethernet and vdpa? Isn't there a general > > > problem for configuring vdpa capabilities (net vs storage etc) and > > > shouldn't we seek to solve your BAR format switch in a similar fashion > > > rather than adding PCI device attrs, which I believe is not done for > > > anything vDPA-related? > > > > The initial support will be for vdpa net. vdpa block and RDMA will follow > > later, and we also need to consider FPGA management. > > > > When it comes to vDPA there is a "vdpa" tool that we intend to support. > > This comes into play after we've switched a device into vdpa mode (using > > this new file). > > For a network device there is also "devlink" to consider. That could be used > > to switch a device into vdpa mode, but it cannot be used to switch it > > back (there is no netdev to operate on). > > My current understanding is that we won't have this issue for RDMA. > > For FPGA management there is no general configuration tool, just what > > fpga_mgr exposes (drivers/fpga). We intend to remove the special PF > > devices we have for this (PCI space is valuable), and use the normal > > network device in stead. I can give more details on this if you want. > > Worst case a special BAR config would be needed for this, but if needed I > > expect we can restrict this to the NIC provisioning stage. > > > > So there is a general problem I think. The solution here is something at > > lower level, which is PCI in this case. > > Another solution would be a proprietary tool, something we are off course > > keen to avoid. > > Okay. Indeed, we could easily bolt something onto devlink, I'd think > but I don't know the space enough to push for one solution over > another. > > Please try to document the problem and the solution... somewhere, tho. > Otherwise the chances that the next vendor with this problem follows > the same approach fall from low to none. Yeah, good point. The obvious thing would be to create a Documentation/networking/device_drivers/ethernet/sfc/sfc/rst Is that generic enough for other vendors to find out, or there a better place? I can do a follow-up patch for this. Martin
