On 5/24/2018 3:13 PM, Ferruh Yigit wrote: > On 5/24/2018 3:02 PM, Alejandro Lucero wrote: >> >> >> On Thu, May 24, 2018 at 11:18 AM, Ferruh Yigit <ferruh.yi...@intel.com >> <mailto:ferruh.yi...@intel.com>> wrote: >> >> On 5/23/2018 5:50 PM, Alejandro Lucero wrote: >> > >> > >> > On Wed, May 23, 2018 at 4:57 PM, Ferruh Yigit <ferruh.yi...@intel.com >> <mailto:ferruh.yi...@intel.com> >> > <mailto:ferruh.yi...@intel.com <mailto:ferruh.yi...@intel.com>>> wrote: >> > >> > On 5/23/2018 1:28 PM, Alejandro Lucero wrote: >> > > DPDK apps can be executed as non-root users but current NFP lock >> > > file for avoiding concurrent accesses to CPP interface is >> precluding >> > > this option or requires to modify system file permissions. >> > > >> > > When the NFP device is bound to VFIO, this driver does not allow >> this >> > > concurrent access, so the lock file is not required at all. >> > > >> > > OVS-DPDK as executed in RedHat distributions is the main NFP user >> > > needing this fix. >> > > >> > > Fixes: c7e9729da6b5 ("net/nfp: support CPP") >> > > >> > > Signed-off-by: Alejandro Lucero <alejandro.luc...@netronome.com >> <mailto:alejandro.luc...@netronome.com> >> <mailto:alejandro.luc...@netronome.com >> <mailto:alejandro.luc...@netronome.com>>> >> > >> > Hi Alejandro, >> > >> > As far as I understand this is to fix a common use case for nfp, >> but it looks >> > like there is already a workaround and only for non-root users. >> > >> > >> > There is a patch submitted to stable versions because this lock was >> also with >> > the old NSPU interface, but as far as I know, there is no patch yet >> for the >> > current upstream tip. >> > >> > >> > >> > What is the priority of the patch, only critical but fixes allowed >> at this >> > point, can we push this one to next release? >> > >> > >> > This is critical for us because RedHat wants to support OVS with our >> card, and >> > when OVS-DPDK is used, this problem is precluding non-root users to >> execute >> > OVS-DPDK. >> >> What exactly this lock for? Does it to prevent multiple primary process >> to >> access CPP interface? >> >> If so this is the know limitation in DPDK, not two separate process can >> driver >> same hardware, this is valid for all devices, why adding a lock unique >> to nfp? >> >> >> Time ago I had, by mistake, two different DPDK processes using same device, >> and >> with UIO, there is no one avoiding this. >> >> You can bound a device to UIO, igb_uio, and then use two different processes >> opening the /dev/uiox file, and it works. > > But this is not anything specific to nfp, isn't it?
Or let me ask something else, is this a fix for ovs-dpdk regular use-case with nfp? Or this is just an extra protection in case multiple process may try to use the NIC. If second, why it is critical? > >> >> The VFIO driver does avoid this situation, but this lock is required for UIO. >> >
