* Richardson, Bruce (bruce.richardson at intel.com) wrote: > > -----Original Message----- > > From: Chris Wright [mailto:chrisw at redhat.com] > > Sent: Friday, June 13, 2014 11:14 AM > > To: Richardson, Bruce > > Cc: Chris Wright; Stephen Hemminger; Thomas Monjalon; dev at dpdk.org > > Subject: Re: [PATCH] igb_uio: cap max VFs at 7 to reserve one for PF > > > > * Richardson, Bruce (bruce.richardson at intel.com) wrote: > > > > > > > > > > -----Original Message----- > > > > From: Chris Wright [mailto:chrisw at redhat.com] > > > > Sent: Friday, June 13, 2014 10:52 AM > > > > To: Richardson, Bruce; Stephen Hemminger > > > > Cc: Thomas Monjalon; dev at dpdk.org > > > > Subject: [PATCH] igb_uio: cap max VFs at 7 to reserve one for PF > > > > > > > > To keep from confusing users, cap max VFs at 7, despite PCI SR-IOV > > > > config > > > > space showing a max of 8. This reserves a queue pair for the PF. > > > > > > > > This issue was cited here: > > > > > > > > http://dpdk.org/ml/archives/dev/2014-April/001832.html > > > > > > > > Cc: Bruce Richardson <bruce.richardson at intel.com> > > > > Cc: Stephen Hemminger <stephen at networkplumber.org> > > > > Signed-off-by: Chris Wright <chrisw at redhat.com> > > > > --- > > > > > > > > This is what Linux kernel driver does. I have only > > > > compile tested it. Stephen sending to you and Bruce > > > > in case you want to Ack and add to your current queue. > > > > > > > > > > Sorry, NAK - at least for this implementation. > > > > Oh, that's fine. > > > > > Hardcoding this to 7 is a bad idea, as the actual max number of VFs > > > supported > > will depend on the actual hardware used. For someone using an 82599, they > > can > > have up to 64 VFs, or 63+PF, so limiting so 7 in that case is a major > > reduction in > > capability. What might work there is querying the max number of VFs and > > limiting to max - 1. > > > > But this is igb_uio, not 82599 (ixgbe). > > igb_uio is used as the supporting kernel module for both the e1000/igb and > ixgbe pmd implementations (as well as for the forthcoming i40e pmd). Despite > the name, it's not just for igb-based NICs.
Oh, right, sorry, was looking at pmd side for each driver. > > > However, even with that, I would suggest that any limit should be > > > possible to > > override. It's entirely possible that someone max actually want to reserve > > the > > full number of VFs, either because they don't want to use the NIC on the > > host at > > all, or because they are happy to use a VF on the host instead. Module > > parameter to allow override might work - and information on it could be > > added > > to the error message when we limit the VFs inside the driver. > > > > It's been a while since I've looked at this, but my recollection is > > the PF must be there (basic mailbox handling, for example). > > > > Would you rather a simple warning message as a hint? > > I'm not sure about the PF still needing to be there or not - I'm not an > expert in that area, so you may indeed be right. > However, as for this patch, I'd probably be ok for now with a version that > queried the max_vfs and limited based on that. If in future we do need to add > an override it should be trivial to add later-on. I'll look at that idea. thanks, -chris
