> -----Original Message----- > From: Burakov, Anatoly <anatoly.bura...@intel.com> > Sent: Thursday, May 6, 2021 4:17 PM > To: Richardson, Bruce <bruce.richard...@intel.com>; dev@dpdk.org > Cc: Van Haaren, Harry <harry.van.haa...@intel.com> > Subject: Re: [PATCH] raw/ioat: fix bus requiring virtual addressing when no > devs > > On 06-May-21 4:09 PM, Bruce Richardson wrote: > > If after a bus scan, there are no devices using a particular bus, then > > that bus should not be taken into account when deciding whether DPDK > > should be run in VA or PA addressing mode. This becomes an issue when > > the DSA bus driver code is used on a system without an IOMMU. The PCI > > bus correctly reports that it only works in PA mode, while the DSA bus - > > also correctly - reports that it works only in VA mode. The difference > > is that there will be no devices found in a scan for the DSA bus, since > > the kernel driver can only present those to userspace in the presence of > > an IOMMU. > > > > While we could change DSA instance to always report that it does not > > care about the addressing mode, this would imply that it could be used > > with DPDK in PA mode which is not the case. Therefore, this patch > > changes the driver to report DC (don't care) in the case where no > > devices are present, and VA otherwise. > > > > NOTE: this addressing mode use of VA-only applies only in the case of > > using DSA through the idxd kernel driver. The use of DSA though vfio-pci > > is unaffected and works as with other PCI devices. > > > > Fixes: b7aaf417f936 ("raw/ioat: add bus driver for device scanning > > automatically") > > > > Reported-by: Harry van Haaren <harry.van.haa...@intel.com> > > Signed-off-by: Bruce Richardson <bruce.richard...@intel.com> > > --- > > Tested-by: Anatoly Burakov <anatoly.bura...@intel.com>
Tested-by: Harry van Haaren <harry.van.haa...@intel.com>