[dpdk-dev] EAL PCI dev problem when using .a file to compile app

[Umar Farooq]

Thanks Bruce. In application compilation command, after adding the
"--no-as-needed" flag and some additional flags including

"-Wl,-lrte_pmd_bond -Wl,-lrte_pmd_vmxnet3_uio -Wl,-lrte_pmd_virtio_uio
-Wl,-lrte_pmd_enic -Wl,-lrte_pmd_i40e -Wl,-lrte_pmd_fm10k
-Wl,-lrte_pmd_ixgbe -Wl,-lrte_pmd_e1000 -Wl,-lrte_pmd_ring
-Wl,-lrte_pmd_af_packet"

solved the issue.

On Thu, Jun 18, 2015 at 3:06 PM, Bruce Richardson <
bruce.richardson at intel.com> wrote:

> On Thu, Jun 18, 2015 at 01:07:33PM +0500, Umar Farooq wrote:
> > Hi
> >
> > I am trying to write an application "abc" using DPDK 2.0.0 that calls
> > rte_eal_init to test if EAL is setup correctly. I have run "helloworld"
> and
> > "l2fwd" applications and they run fine on my setup.
> >
> > A new thing that i am trying is to create a libdpdk.a file using build
> > target "x86_64-native-linuxapp-gcc" and use it to compile my application.
> > The application simply calls "rte_eal_init(argc, argv)" and exits. It
> > compiles successfully and runs but the EAL doesn't initialize the PCI
> > devices.
> >
> > The flow is this:
> >
> > 1. The method to create libdpdk.a is by using this shell script:
> > #bin/bash
> > rm -f libdpdk.a
> > cp /path_to/dpdk/x86_64-native-linuxapp-gcc/lib/* .
> > DPDK_LIBS=$(ls *.a)
> > for file in *.a; do
> >     ar -x "$file"
> > done
> > ar -rcs libdpdk.a *.o
> >
> > 2. Application is compiled using the command:
> > gcc abc.c /path_to/dpdk/libdpdk.a
> > -I/path_to/dpdk/x86_64-native-linuxapp-gcc/include -lpthread -lrt -ldl
> > -mssse3 -lm -o abc
> >
> > 3. After the successful compilation, the app is run using the command:
> > ./abc -c c -n 4 -b 00:03.0
> >
> > 4. Application calls rte_eal_init(argc, argv), which calls
> > rte_eal_pci_probe(), which calls pci_probe_all_drivers().
> >
> > 5. In the last function called, pci_probe_all_drivers(struct
> rte_pci_device
> > *dev) in
> > dpdk/lib/librte_eal/common/eal_common_pci.c file, the control never
> enters
> > the loop:
> > TAILQ_FOREACH(dr, &pci_driver_list, next) {
> >                 rc = rte_eal_pci_probe_one_driver(dr, dev);
> >                 if (rc < 0)
> >                         /* negative value is an error */
> >                         return -1;
> >                 if (rc > 0)
> >                         /* positive value means driver not found */
> >                         continue;
> >                 return 0;
> >         }
> >
> > and the function always returns 1.
> >
> > If the application is compiled using normal Makefile as used by l2fwd or
> > helloworld example apps, this problem doesn't occur and application calls
> > the "rte_eal_pci_probe_one_driver(dr, dev)" in "TAILQ_FOREACH" loop.
> >
> > The question is what am I missing while creating the libdpdk.a and
> > compiling application using it?
> >
> > Thanks for your time.
> >
> > Regards
> > Umar
>
> This may be due to a missing "--no-as-needed" flag in the link stage of
> your
> application. If so, the drivers are not getting registered at startup, so
> pci
> probing fails to find your devices.
>
> /Bruce
>