[dpdk] dpdk编译成动态库使用 -- PCI port自动发现与pmd动态加载

1.  修改配置文件 .conf, 设置如下变量的值.

[root@D129 x86_64-native-linuxapp-gcc]# cat dpdk/x86_64-native-linuxapp-gcc/.config |grep SHARE
CONFIG_RTE_BUILD_SHARED_LIB=y

2.  这个时候, 再编译的 dpdk app就会自动链接dpdk的动态库. 如下:

[root@D129 app]# ldd testpmd
        linux-vdso.so. =>  (0x00007ffed89fd000)
        librte_kni.so. => /root/Src/copyright/j/dpdk/x86_64-native-linuxapp-gcc/lib/librte_kni.so. (0x00007fe9c983f000)
        librte_pipeline.so. => /root/Src/copyright/j/dpdk/x86_64-native-linuxapp-gcc/lib/librte_pipeline.so. (0x00007fe9c962b000)
        librte_table.so. => /root/Src/copyright/j/dpdk/x86_64-native-linuxapp-gcc/lib/librte_table.so. (0x00007fe9c93ed000)
        librte_port.so. => /root/Src/copyright/j/dpdk/x86_64-native-linuxapp-gcc/lib/librte_port.so. (0x00007fe9c9191000)
        librte_pdump.so. => /root/Src/copyright/j/dpdk/x86_64-native-linuxapp-gcc/lib/librte_pdump.so. (0x00007fe9c8d77000)
        librte_distributor.so. => /root/Src/copyright/j/dpdk/x86_64-native-linuxapp-gcc/lib/librte_distributor.so. (0x00007fe9c8b74000)
        librte_reorder.so. => /root/Src/copyright/j/dpdk/x86_64-native-linuxapp-gcc/lib/librte_reorder.so. (0x00007fe9c8965000)
        librte_ip_frag.so. => /root/Src/copyright/j/dpdk/x86_64-native-linuxapp-gcc/lib/librte_ip_frag.so. (0x00007fe9c8724000)
        librte_meter.so. => /root/Src/copyright/j/dpdk/x86_64-native-linuxapp-gcc/lib/librte_meter.so. (0x00007fe9c8521000)
        librte_sched.so. => /root/Src/copyright/j/dpdk/x86_64-native-linuxapp-gcc/lib/librte_sched.so. (0x00007fe9c830d000)
        librte_lpm.so. => /root/Src/copyright/j/dpdk/x86_64-native-linuxapp-gcc/lib/librte_lpm.so. (0x00007fe9c80ff000)
        librte_acl.so. => /root/Src/copyright/j/dpdk/x86_64-native-linuxapp-gcc/lib/librte_acl.so. (0x00007fe9c7ee5000)
        librte_jobstats.so. => /root/Src/copyright/j/dpdk/x86_64-native-linuxapp-gcc/lib/librte_jobstats.so. (0x00007fe9c7ce2000)
        librte_power.so. => /root/Src/copyright/j/dpdk/x86_64-native-linuxapp-gcc/lib/librte_power.so. (0x00007fe9c7acd000)
        librte_timer.so. => /root/Src/copyright/j/dpdk/x86_64-native-linuxapp-gcc/lib/librte_timer.so. (0x00007fe9c78c3000)
        librte_hash.so. => /root/Src/copyright/j/dpdk/x86_64-native-linuxapp-gcc/lib/librte_hash.so. (0x00007fe9c76af000)
        librte_vhost.so. => /root/Src/copyright/j/dpdk/x86_64-native-linuxapp-gcc/lib/librte_vhost.so. (0x00007fe9c7477000)
        librte_kvargs.so. => /root/Src/copyright/j/dpdk/x86_64-native-linuxapp-gcc/lib/librte_kvargs.so. (0x00007fe9c7274000)
        librte_mbuf.so. => /root/Src/copyright/j/dpdk/x86_64-native-linuxapp-gcc/lib/librte_mbuf.so. (0x00007fe9c7071000)
        libethdev.so. => /root/Src/copyright/j/dpdk/x86_64-native-linuxapp-gcc/lib/libethdev.so. (0x00007fe9c6dd6000)
        librte_cryptodev.so. => /root/Src/copyright/j/dpdk/x86_64-native-linuxapp-gcc/lib/librte_cryptodev.so. (0x00007fe9c6bc1000)
        librte_mempool.so. => /root/Src/copyright/j/dpdk/x86_64-native-linuxapp-gcc/lib/librte_mempool.so. (0x00007fe9c69b9000)
        librte_ring.so. => /root/Src/copyright/j/dpdk/x86_64-native-linuxapp-gcc/lib/librte_ring.so. (0x00007fe9c67b5000)
        librte_eal.so. => /root/Src/copyright/j/dpdk/x86_64-native-linuxapp-gcc/lib/librte_eal.so. (0x00007fe9c6546000)
        librte_cmdline.so. => /root/Src/copyright/j/dpdk/x86_64-native-linuxapp-gcc/lib/librte_cmdline.so. (0x00007fe9c633b000)
        librte_cfgfile.so. => /root/Src/copyright/j/dpdk/x86_64-native-linuxapp-gcc/lib/librte_cfgfile.so. (0x00007fe9c6137000)
        librte_pmd_bond.so. => /root/Src/copyright/j/dpdk/x86_64-native-linuxapp-gcc/lib/librte_pmd_bond.so. (0x00007fe9c5efa000)
        libgcc_s.so. => /lib64/libgcc_s.so. (0x00007fe9c5cd9000)
        libdl.so. => /lib64/libdl.so. (0x00007fe9c5ad4000)
        libpthread.so. => /lib64/libpthread.so. (0x00007fe9c58b8000)
        libc.so. => /lib64/libc.so. (0x00007fe9c54f5000)
        /lib64/ld-linux-x86-.so. (0x00007fe9c9a51000)
        libm.so. => /lib64/libm.so. (0x00007fe9c51f2000)
        librt.so. => /lib64/librt.so. (0x00007fe9c4fea000)
[root@D129 app]# 

3.  但是与static的时候对比, 你会发现有如下的问题:

　　用static链接的时候, rte_init的时候,会扫描所有的PCI设备,找到所有可用的port, 如下:

[root@D129 app]# ./testpmd
EAL: Detected  lcore(s)
EAL: Probing VFIO support...
EAL: WARNING: cpu flags constant_tsc=yes nonstop_tsc=no -> using unreliable clock cycles !
EAL: PCI device 0000:00:03.0 on NUMA socket -1
EAL:   probe driver: 1af4:1000 rte_virtio_pmd
EAL: PCI device 0000:00:04.0 on NUMA socket -1
EAL:   probe driver: 1af4:1000 rte_virtio_pmd
USER1: create a new mbuf pool <mbuf_pool_socket_0>: n=, size=, socket=
RING: Cannot reserve memory
EAL: Error - exiting with code:
  Cause: Creation of mbuf pool for socket  failed: Cannot allocate memory
[root@D129 app]# 

　　在使用shared so库的时候, 会发现,dpdk app扫描不到任何 PCI 设备了. 如下:

[root@D129 app]# ./testpmd
EAL: Detected  lcore(s)
EAL: Probing VFIO support...
EAL: WARNING: cpu flags constant_tsc=yes nonstop_tsc=no -> using unreliable clock cycles !
EAL: No probed ethernet devices
USER1: create a new mbuf pool <mbuf_pool_socket_0>: n=, size=, socket=
RING: Cannot reserve memory
EAL: Error - exiting with code:
  Cause: Creation of mbuf pool for socket  failed: Cannot allocate memory

　　这个时候,我们ldd app,会发现, 它并没有ld到pmd的so,

[root@D129 app]# ldd testpmd |grep pmd
        librte_pmd_bond.so. => /root/Src/copyright/j/dpdk/x86_64-native-linuxapp-gcc/lib/librte_pmd_bond.so. (0x00007fa25689a000)
[root@D129 app]# 

　　猜测, dpdk在shared的情况下, pmd的库,是需要动态加载的. 并找到如下参数:

[root@D129 app]# ./testpmd -h |grep -A1 LIB.so
  -d LIB.so|DIR       Add a driver or driver directory
                      (can be used multiple times)

　　使用 -d 参数制定 virtio的so, (我的虚拟机是virtio的网络设备), 果然生效了

[root@D129 app]# ./testpmd  -d ../lib/librte_pmd_virtio.so
EAL: Detected  lcore(s)
EAL: Probing VFIO support...
EAL: WARNING: cpu flags constant_tsc=yes nonstop_tsc=no -> using unreliable clock cycles !
EAL: PCI device ::03.0 on NUMA socket -
EAL:   probe driver: 1af4: rte_virtio_pmd
EAL: PCI device ::04.0 on NUMA socket -
EAL:   probe driver: 1af4: rte_virtio_pmd
USER1: create a new mbuf pool <mbuf_pool_socket_0>: n=, size=, socket=
RING: Cannot reserve memory
EAL: Error - exiting with code:
  Cause: Creation of mbuf pool for socket  failed: Cannot allocate memory
[root@D129 app]# 

4.  问题分析

　　参考 dpdk 的源码 ../dpdk/lib/librte_eal/common/eal_common_options.c::eal_plugins_init()

　　在读取 -d 参数的同时, dpdk在 rte_init函数中还会读取 RTE_EAL_PMD_PATH 目录下的文件,  所有读到的文件会使用 dlopen() 打开. 详细逻辑参见代码.

　　变量RTE_EAL_PMD_PATH的值由CONFIG_RTE_EAL_PMD_PATH在编译的时候决定.

5.  参考redhat的rpm spec, 最终的解决方案是这样的.

5.1  生成一个编译与运行时都存在的目录: /lib64/tong-dpdk-pmds/,

5.2  将所以pmd软链接到这个目录下

[root@D129 app]# ll /lib64/tong-dpdk-pmds/
total
lrwxrwxrwx  root root  Jul  : librte_pmd_af_packet.so. -> ../librte_pmd_af_packet.so.
lrwxrwxrwx  root root  Jul  : librte_pmd_bnxt.so. -> ../librte_pmd_bnxt.so.
lrwxrwxrwx  root root  Jul  : librte_pmd_bond.so. -> ../librte_pmd_bond.so.
lrwxrwxrwx  root root  Jul  : librte_pmd_cxgbe.so. -> ../librte_pmd_cxgbe.so.
lrwxrwxrwx  root root  Jul  : librte_pmd_e1000.so. -> ../librte_pmd_e1000.so.
lrwxrwxrwx  root root  Jul  : librte_pmd_ena.so. -> ../librte_pmd_ena.so.
lrwxrwxrwx  root root  Jul  : librte_pmd_enic.so. -> ../librte_pmd_enic.so.
lrwxrwxrwx  root root  Jul  : librte_pmd_fm10k.so. -> ../librte_pmd_fm10k.so.
lrwxrwxrwx  root root  Jul  : librte_pmd_i40e.so. -> ../librte_pmd_i40e.so.
lrwxrwxrwx  root root  Jul  : librte_pmd_ixgbe.so. -> ../librte_pmd_ixgbe.so.
lrwxrwxrwx  root root  Jul  : librte_pmd_null_crypto.so. -> ../librte_pmd_null_crypto.so.
lrwxrwxrwx  root root  Jul  : librte_pmd_null.so. -> ../librte_pmd_null.so.
lrwxrwxrwx  root root  Jul  : librte_pmd_ring.so. -> ../librte_pmd_ring.so.
lrwxrwxrwx  root root  Jul  : librte_pmd_vhost.so. -> ../librte_pmd_vhost.so.
lrwxrwxrwx  root root  Jul  : librte_pmd_virtio.so. -> ../librte_pmd_virtio.so.
lrwxrwxrwx  root root  Jul  : librte_pmd_vmxnet3_uio.so. -> ../librte_pmd_vmxnet3_uio.so.

5.2 在编译前, 设置变量CONFIG_RTE_EAL_PMD_PATH

[root@D129 app]# cat ../.config |grep PATH
CONFIG_RTE_EAL_PMD_PATH="/lib64/tong-dpdk-pmds/"

以上, dpdk app便可以使用 shared lib 正常运行了.

6. 另一个方案:  使用 -d, 需要神马加神马, 比如:

[root@D129 app]# ./testpmd  -d ../lib/librte_pmd_virtio.so  -d ../lib/librte_pmd_ixgbe.so

完.