[dpdk-dev] [PATCH 1/1 v2] eal: Fix misleading error messages, errno can't be trusted.

[Jean Tourrilhes]

 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..5df9f6a 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 != MAP_FAILED)
+                       /* 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..b036ffc 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 != MAP_FAILED)
+                               /* 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 "