[dpdk-dev] [PATCH v2 5/7] mem: modify error message for DMA mask check

[Alejandro Lucero]

If DMA mask checks shows mapped memory out of the supported range
specified by the DMA mask, nothing can be done but return an error
an report the error. This can imply the app not being executed at
all or precluding dynamic memory allocation once the app is running.
In any case, we can advice the user to force IOVA as PA if currently
IOVA being VA and user being root.

Signed-off-by: Alejandro Lucero <alejandro.lucero at netronome.com>
---
 lib/librte_eal/common/malloc_heap.c | 41 +++++++++++++++++++++++++----
 1 file changed, 36 insertions(+), 5 deletions(-)

diff --git a/lib/librte_eal/common/malloc_heap.c b/lib/librte_eal/common/malloc_heap.c
index 4997c5ef5..c2c112aa6 100644
--- a/lib/librte_eal/common/malloc_heap.c
+++ b/lib/librte_eal/common/malloc_heap.c
@@ -321,13 +321,44 @@ alloc_pages_on_heap(struct malloc_heap *heap, uint64_t pg_sz, size_t elt_size,
 		goto fail;
 	}
 
-	if (mcfg->dma_maskbits) {
-		if (rte_mem_check_dma_mask(mcfg->dma_maskbits)) {
+	/*
+	 * Once we have all the memseg lists configured, if there is a dma mask
+	 * set, check iova addresses are not out of range. Otherwise the device
+	 * setting the dma mask could have problems with the mapped memory.
+	 *
+	 * There are two situations when this can happen:
+	 *	1) memory initialization
+	 *	2) dynamic memory allocation
+	 *
+	 * For 1), an error when checking dma mask implies app can not be
+	 * executed. For 2) implies the new memory can not be added.
+	 */
+	if (mcfg->dma_maskbits &&
+	    rte_mem_check_dma_mask(mcfg->dma_maskbits)) {
+		/*
+		 * Currently this can only happen if IOMMU is enabled
+		 * and the address width supported by the IOMMU hw is
+		 * not enough for using the memory mapped IOVAs.
+		 *
+		 * If IOVA is VA, advice to try with '--iova-mode pa'
+		 * which could solve some situations when IOVA VA is not
+		 * really needed.
+		 */
+		RTE_LOG(ERR, EAL,
+			"%s(): couldn't allocate memory due to IOVA exceeding limits of current DMA mask\n",
+			__func__);
+
+		/*
+		 * If IOVA is VA and it is possible to run with IOVA PA,
+		 * because user is root, give and advice for solving the
+		 * problem.
+		 */
+		if ((rte_eal_iova_mode() == RTE_IOVA_VA) &&
+		     rte_eal_using_phys_addrs())
 			RTE_LOG(ERR, EAL,
-				"%s(): couldn't allocate memory due to DMA mask\n",
+				"%s(): Please try initializing EAL with --iova-mode=pa parameter\n",
 				__func__);
-			goto fail;
-		}
+		goto fail;
 	}
 
 	/* add newly minted memsegs to malloc heap */
-- 
2.17.1