[dpdk-dev] [PATCH 1/1] eal: Fix misleading error messages, errno can't be trusted.

[Jean Tourrilhes <jt@labs.hpe.com>]

 lib/librte_eal/linuxapp/eal/eal.c        | 14 +++++++++++---
 lib/librte_eal/linuxapp/eal/eal_memory.c | 16 ++++++++++++----
 2 files changed, 23 insertions(+), 7 deletions(-)

diff --git a/lib/librte_eal/linuxapp/eal/eal.c b/lib/librte_eal/linuxapp/eal/eal.c
index 3fb2188..f6907f5 100644
--- a/lib/librte_eal/linuxapp/eal/eal.c
+++ b/lib/librte_eal/linuxapp/eal/eal.c
@@ -238,7 +238,8 @@ rte_eal_config_attach(void)
 	mem_config = (struct rte_mem_config *) mmap(NULL, sizeof(*mem_config),
 			PROT_READ, MAP_SHARED, mem_cfg_fd, 0);
 	if (mem_config == MAP_FAILED)
-		rte_panic("Cannot mmap memory for rte_config\n");
+		rte_panic("Cannot mmap memory for rte_config! error %i (%s)\n",
+			  errno, strerror(errno));
 
 	rte_config.mem_config = mem_config;
 }
@@ -263,9 +264,16 @@ rte_eal_config_reattach(void)
 	mem_config = (struct rte_mem_config *) mmap(rte_mem_cfg_addr,
 			sizeof(*mem_config), PROT_READ | PROT_WRITE, MAP_SHARED,
 			mem_cfg_fd, 0);
+	if (mem_config == MAP_FAILED || mem_config != rte_mem_cfg_addr) {
+		if (mem_config != rte_mem_cfg_addr)
+			/* errno is stale, don't use */
+			rte_panic("Cannot mmap memory for rte_config at [%p], got [%p] - please use '--base-virtaddr' option\n",
+				  rte_mem_cfg_addr, mem_config);
+		else
+			rte_panic("Cannot mmap memory for rte_config! error %i (%s)\n",
+				  errno, strerror(errno));
+	}
 	close(mem_cfg_fd);
-	if (mem_config == MAP_FAILED || mem_config != rte_mem_cfg_addr)
-		rte_panic("Cannot mmap memory for rte_config\n");
 
 	rte_config.mem_config = mem_config;
 }
diff --git a/lib/librte_eal/linuxapp/eal/eal_memory.c b/lib/librte_eal/linuxapp/eal/eal_memory.c
index 41e0a92..f2549cc 100644
--- a/lib/librte_eal/linuxapp/eal/eal_memory.c
+++ b/lib/librte_eal/linuxapp/eal/eal_memory.c
@@ -1615,10 +1615,18 @@ rte_eal_hugepage_attach(void)
 				 PROT_READ, MAP_PRIVATE, fd_zero, 0);
 		if (base_addr == MAP_FAILED ||
 		    base_addr != mcfg->memseg[s].addr) {
-			RTE_LOG(ERR, EAL, "Could not mmap %llu bytes "
-				"in /dev/zero to requested address [%p]: '%s'\n",
-				(unsigned long long)mcfg->memseg[s].len,
-				mcfg->memseg[s].addr, strerror(errno));
+			if (base_addr != mcfg->memseg[s].addr)
+				/* errno is stale, don't use */
+				RTE_LOG(ERR, EAL, "Could not mmap %llu bytes "
+					"in /dev/zero at [%p], got [%p] - "
+					"please use '--base-virtaddr' option\n",
+					(unsigned long long)mcfg->memseg[s].len,
+					mcfg->memseg[s].addr, base_addr);
+			else
+				RTE_LOG(ERR, EAL, "Could not mmap %llu bytes "
+					"in /dev/zero at [%p]: '%s'\n",
+					(unsigned long long)mcfg->memseg[s].len,
+					mcfg->memseg[s].addr, strerror(errno));
 			if (aslr_enabled() > 0) {
 				RTE_LOG(ERR, EAL, "It is recommended to "
 					"disable ASLR in the kernel "