On Mon, 2020-09-14 at 11:38 -0300, Jason Gunthorpe wrote: > On Mon, Sep 14, 2020 at 02:24:06PM +0000, Clint Sbisa wrote: > > On Mon, Sep 14, 2020 at 11:17:26AM -0300, Jason Gunthorpe wrote: > > > On Fri, Sep 11, 2020 at 09:42:25PM +0000, Clint Sbisa wrote: > > > > > > > There's no DMA involved with this BAR-- the driver writes a > > > > portion of the > > > > packet contents in addition to the descriptors, which generally > > > > increases the > > > > number of TLPs if write-combine isn't used. Furthermore, this > > > > BAR is only used > > > > for writes and never for reads. > > > > > > You use DPDK without DMA? How does receive work? > > > > That was not worded well. DMA is used, but the first X bytes of the > > packet are > > written directly to this BAR instead of being DMA'd-- the rest of > > the data is > > DMA'd. > > which is back to my original question, how do you do DMA using > /sys/xx/resources? Why not use VFIO like everything else? Note: All this doesnt' change the fact that sys/xx/resources_wc exists for other archs and I see no reasons so far not to have it on ARM... Cheers, Ben.
