[dpdk-dev] [PATCH] pci/uio: enable prefetchable resources mapping

[Changpeng Liu]

For PCI prefetchable resources, Linux will create a
write combined file as well, the library will try
to map resourceX_wc file first, if the file does
not exist, then it will map resourceX as usual.

Signed-off-by: Changpeng Liu <changpeng....@intel.com>
---
 drivers/bus/pci/linux/pci_uio.c | 19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/drivers/bus/pci/linux/pci_uio.c b/drivers/bus/pci/linux/pci_uio.c
index d423e4b..2957a5f 100644
--- a/drivers/bus/pci/linux/pci_uio.c
+++ b/drivers/bus/pci/linux/pci_uio.c
@@ -293,7 +293,7 @@
 
        /* update devname for mmap  */
        snprintf(devname, sizeof(devname),
-                       "%s/" PCI_PRI_FMT "/resource%d",
+                       "%s/" PCI_PRI_FMT "/resource%d_wc",
                        rte_pci_get_sysfs_path(),
                        loc->domain, loc->bus, loc->devid,
                        loc->function, res_idx);
@@ -307,13 +307,22 @@
        }
 
        /*
-        * open resource file, to mmap it
+        * open prefetchable resource file first, try to mmap it
         */
        fd = open(devname, O_RDWR);
        if (fd < 0) {
-               RTE_LOG(ERR, EAL, "Cannot open %s: %s\n",
-                               devname, strerror(errno));
-               goto error;
+               snprintf(devname, sizeof(devname),
+                               "%s/" PCI_PRI_FMT "/resource%d",
+                               rte_pci_get_sysfs_path(),
+                               loc->domain, loc->bus, loc->devid,
+                               loc->function, res_idx);
+               /* then try to map resource file */
+               fd = open(devname, O_RDWR);
+               if (fd < 0) {
+                       RTE_LOG(ERR, EAL, "Cannot open %s: %s\n",
+                                       devname, strerror(errno));
+                       goto error;
+               }
        }
 
        /* try mapping somewhere close to the end of hugepages */
-- 
1.9.3