> -----Original Message----- > From: Matan Azrad <[email protected]> > Sent: Sunday, September 22, 2019 9:59 > To: Slava Ovsiienko <[email protected]>; [email protected] > Cc: Raslan Darawsheh <[email protected]> > Subject: RE: [PATCH] net/mlx5: fix transmit doorbell register write barrier > > Hi Slava > > Questions inline. >
[.. skipped ...] > > + /* Check the doorbell register mapping type. */ > > + cmd = txq_ctrl->uar_mmap_offset / page_size; > > + cmd >>= MLX5_UAR_MMAP_CMD_SHIFT; > > + cmd &= MLX5_UAR_MMAP_CMD_MASK; > > + if (cmd == MLX5_MMAP_GET_NC_PAGES_CMD) > > + txq_ctrl->txq.db_nc = 1; > > Are you sure we can't retrieve the value in compile time? It is deduced by rdma_core library in runtime, grounding on the MLX5_SHUT_UP_BF environment variable. This variable is checked by rdma library in ibv device open calls (both verbs/dv). > > > #ifndef RTE_ARCH_64 > > /* Assign an UAR lock according to UAR page number */ > > lock_idx = (txq_ctrl->uar_mmap_offset / page_size) & @@ -281,6 > > +289,7 @@ > > uintptr_t uar_va; > > uintptr_t offset; > > const size_t page_size = sysconf(_SC_PAGESIZE); > > + unsigned int cmd; > > > > assert(ppriv); > > /* > > @@ -300,6 +309,12 @@ > > } > > addr = RTE_PTR_ADD(addr, offset); > > ppriv->uar_table[txq->idx] = addr; > > + /* Check the doorbell register mapping type. */ > > + cmd = txq_ctrl->uar_mmap_offset / page_size; > > + cmd >>= MLX5_UAR_MMAP_CMD_SHIFT; > > + cmd &= MLX5_UAR_MMAP_CMD_MASK; > > + if (cmd == MLX5_MMAP_GET_NC_PAGES_CMD) > > + txq_ctrl->txq.db_nc = 1; > > Looks like double code. > Maybe it is better to get the value by a MACRO? Yes, it would be better. WBR, Slava
