> -----Original Message----- > From: Doug Ledford [mailto:dledford@xxxxxxxxxx] > Sent: Thursday, July 23, 2015 4:33 PM > To: Steve Wise > Cc: linux-rdma@xxxxxxxxxxxxxxx > Subject: Re: [PATCH] RDMA/cxgb3: fail get_dma_mr if the memory footprint can exceed 32b > > On 07/22/2015 03:14 PM, Steve Wise wrote: > > T3 HW only supports MRs of length < 4GB. If the system can have more > > than that we need to fail dma mr allocation so we con't create a MR that > > cannot span the entire possible memory space. > > > > Signed-off-by: Steve Wise <swise@xxxxxxxxxxxxxxxxxxxxx> > > --- > > > > drivers/infiniband/hw/cxgb3/iwch_provider.c | 4 ++++ > > 1 files changed, 4 insertions(+), 0 deletions(-) > > > > diff --git a/drivers/infiniband/hw/cxgb3/iwch_provider.c b/drivers/infiniband/hw/cxgb3/iwch_provider.c > > index b1b7323..bbbe018 100644 > > --- a/drivers/infiniband/hw/cxgb3/iwch_provider.c > > +++ b/drivers/infiniband/hw/cxgb3/iwch_provider.c > > @@ -736,6 +736,10 @@ static struct ib_mr *iwch_get_dma_mr(struct ib_pd *pd, int acc) > > /* > > * T3 only supports 32 bits of size. > > */ > > + if (sizeof(phys_addr_t) > 4) { > > + pr_warn_once(MOD "Cannot support dma_mrs on this platform.\n"); > > + return ERR_PTR(-ENOTSUPP); > > + } > > bl.size = 0xffffffff; > > bl.addr = 0; > > kva = 0; > > Should this be a static check of the pointer size versus installed > memory? Would it be possible to have this work for machines with less > than 4GB of physical memory even if they have 64bit pointers, or are you > concerned that hotplug memory could take us over the limit after > registration and cause problems? NFSRDMA doesn't need dma-mrs for T3 since it has FRMR + local dma lkey support. And since the deficiency really can cause problems on 64b systems if the memory grows > 4GB after dma-mr allocation, I decided to just not allow them for potential large memory systems. Steve -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
