|author||Moti Haimovsky <email@example.com>||2018-07-12 15:01:31 +0300|
|committer||Shahaf Shuler <firstname.lastname@example.org>||2018-07-12 14:34:59 +0200|
net/mlx5: support 32-bit systems
This patch adds support for building and running mlx5 PMD on 32bit systems such as i686. The main issue to tackle was handling the 32bit access to the UAR as quoted from the mlx5 PRM: QP and CQ DoorBells require 64-bit writes. For best performance, it is recommended to execute the QP/CQ DoorBell as a single 64-bit write operation. For platforms that do not support 64 bit writes, it is possible to issue the 64 bits DoorBells through two consecutive writes, each write 32 bits, as described below: * The order of writing each of the Dwords is from lower to upper addresses. * No other DoorBell can be rung (or even start ringing) in the midst of an on-going write of a DoorBell over a given UAR page. The last rule implies that in a multi-threaded environment, the access to a UAR page (which can be accessible by all threads in the process) must be synchronized (for example, using a semaphore) unless an atomic write of 64 bits in a single bus operation is guaranteed. Such a synchronization is not required for when ringing DoorBells on different UAR pages. Signed-off-by: Moti Haimovsky <email@example.com> Acked-by: Yongseok Koh <firstname.lastname@example.org>
Diffstat (limited to 'drivers/net/mlx5/mlx5_defs.h')
1 files changed, 16 insertions, 2 deletions
diff --git a/drivers/net/mlx5/mlx5_defs.h b/drivers/net/mlx5/mlx5_defs.h
index 5bbbec2..f6ec415 100644
@@ -87,14 +87,28 @@
#define MLX5_LINK_STATUS_TIMEOUT 10
/* Reserved address space for UAR mapping. */
-#define MLX5_UAR_SIZE (1ULL << 32)
+#define MLX5_UAR_SIZE (1ULL << (sizeof(uintptr_t) * 4))
/* Offset of reserved UAR address space to hugepage memory. Offset is used here
* to minimize possibility of address next to hugepage being used by other code
* in either primary or secondary process, failing to map TX UAR would make TX
* packets invisible to HW.
-#define MLX5_UAR_OFFSET (1ULL << 32)
+#define MLX5_UAR_OFFSET (1ULL << (sizeof(uintptr_t) * 4))
+/* Maximum number of UAR pages used by a port,
+ * These are the size and mask for an array of mutexes used to synchronize
+ * the access to port's UARs on platforms that do not support 64 bit writes.
+ * In such systems it is possible to issue the 64 bits DoorBells through two
+ * consecutive writes, each write 32 bits. The access to a UAR page (which can
+ * be accessible by all threads in the process) must be synchronized
+ * (for example, using a semaphore). Such a synchronization is not required
+ * when ringing DoorBells on different UAR pages.
+ * A port with 512 Tx queues uses 8, 4kBytes, UAR pages which are shared
+ * among the ports.
+#define MLX5_UAR_PAGE_NUM_MAX 64
+#define MLX5_UAR_PAGE_NUM_MASK ((MLX5_UAR_PAGE_NUM_MAX) - 1)
/* Log 2 of the default number of strides per WQE for Multi-Packet RQ. */
#define MLX5_MPRQ_STRIDE_NUM_N 6U