Re: [dpdk-dev] [dpdk-users] DPDK 16.04 link changes cause PMD drivers to not be loaded

[Aurojit Panda <apanda@cs.berkeley.edu>]

[The original report is included below for your convenience]

Thomas Monjalon wrote:
> 2016-04-21 08:01, Aurojit Panda:
>> Panu Matilainen wrote:
> [...]
>>> Again, PMDs are *plugins* that are *meant* to be loaded at runtime.
>>> That allows for all sorts of flexibility especially
>>> for packaging and shipping, at some extra cost in setup complexity.
>> I am all for a plugin architecture, I was merely suggesting that you
>> embed some path infromation at the beginning. Also please note:
>> (a) This behavior changed recently.
>
> What changed recently?
>
>> (b) This change is entirely undocumented, which is why I was reporting
>> it in the first place.
>> (c) It is actually quite unintutive, because previously ensuring
>> LD_LIBRARY_PATH was correct was all that was required
>> to get any DPDK application to interact with ports.
>
> ?
> Are you talking about combined library?
>
>>> For your own purposes, you can of course tweak the linking settings
>>> as much as you like. Look for "plugins" in mk/rte.app.mk and change
>>> the shared lib condition on the line above to "y" and there you have it.
>>> But that's not the way plugins are meant to be used.
>> That is not a reasonable solution given that it makes it very hard to
>> track future changes to DPDK without merges.
>> My alternatives neither break people's abilities to use plugins,
>> nor do they impact behavior.
>
> Please do not hesitate to send some patch to show your solution.
> Thanks

I was trying to run testpmd from DPDK 16.04 on Linux with kernel version 4.4.0-1 (ld version 2.26). My machine has two
XL710QDA2 NICs, and I built DPDK as a shared, combined library (i.e., CONFIG_RTE_BUILD_SHARED_LIB=y and
CONFIG_RTE_BUILD_COMBINE_LIBS=y in config/common_linuxapp). I found that the issue is due to ld not linking against all
libraries with the new linker script (introduced in 948fd64befc3726) but am not sure how to fix this. As evidence for
this being caused by this change:

$ LD_TRACE_LOADED_OBJECTS=y ./testpmd -c 0x1c00 -n 4 -w 82:00.0 -w 82:00.1 --file-prefix "send" -- -i
           linux-vdso.so.1 (0x00007ffe11b3e000)
           librte_distributor.so.1.1 => /home/apanda/e2d2/3rdparty/dpdk/build/lib/librte_distributor.so.1.1
(0x00007fa55eb85000)
           librte_reorder.so.1.1 => /home/apanda/e2d2/3rdparty/dpdk/build/lib/librte_reorder.so.1.1 (0x00007fa55e982000)
           librte_pipeline.so.3.1 => /home/apanda/e2d2/3rdparty/dpdk/build/lib/librte_pipeline.so.3.1 (0x00007fa55e77d000)
           librte_table.so.2.1 => /home/apanda/e2d2/3rdparty/dpdk/build/lib/librte_table.so.2.1 (0x00007fa55e55e000)
           librte_port.so.2.1 => /home/apanda/e2d2/3rdparty/dpdk/build/lib/librte_port.so.2.1 (0x00007fa55e34e000)
           librte_timer.so.1.1 => /home/apanda/e2d2/3rdparty/dpdk/build/lib/librte_timer.so.1.1 (0x00007fa55e145000)
           librte_hash.so.2.1 => /home/apanda/e2d2/3rdparty/dpdk/build/lib/librte_hash.so.2.1 (0x00007fa55df37000)
           librte_jobstats.so.1.1 => /home/apanda/e2d2/3rdparty/dpdk/build/lib/librte_jobstats.so.1.1 (0x00007fa55dd35000)
           librte_lpm.so.2.1 => /home/apanda/e2d2/3rdparty/dpdk/build/lib/librte_lpm.so.2.1 (0x00007fa55db2e000)
           librte_power.so.1.1 => /home/apanda/e2d2/3rdparty/dpdk/build/lib/librte_power.so.1.1 (0x00007fa55d91f000)
           librte_acl.so.2.1 => /home/apanda/e2d2/3rdparty/dpdk/build/lib/librte_acl.so.2.1 (0x00007fa55d705000)
           librte_meter.so.1.1 => /home/apanda/e2d2/3rdparty/dpdk/build/lib/librte_meter.so.1.1 (0x00007fa55d504000)
           librte_sched.so.1.1 => /home/apanda/e2d2/3rdparty/dpdk/build/lib/librte_sched.so.1.1 (0x00007fa55d2fd000)
           librte_vhost.so.2.1 => /home/apanda/e2d2/3rdparty/dpdk/build/lib/librte_vhost.so.2.1 (0x00007fa55d0e6000)
           librte_kvargs.so.1.1 => /home/apanda/e2d2/3rdparty/dpdk/build/lib/librte_kvargs.so.1.1 (0x00007fa55cee4000)
           librte_mbuf.so.2.1 => /home/apanda/e2d2/3rdparty/dpdk/build/lib/librte_mbuf.so.2.1 (0x00007fa55cce2000)
           librte_ip_frag.so.1.1 => /home/apanda/e2d2/3rdparty/dpdk/build/lib/librte_ip_frag.so.1.1 (0x00007fa55cada000)
           libethdev.so.3.1 => /home/apanda/e2d2/3rdparty/dpdk/build/lib/libethdev.so.3.1 (0x00007fa55c84f000)
           librte_cryptodev.so.1.1 => /home/apanda/e2d2/3rdparty/dpdk/build/lib/librte_cryptodev.so.1.1 (0x00007fa55c647000)
           librte_mempool.so.1.1 => /home/apanda/e2d2/3rdparty/dpdk/build/lib/librte_mempool.so.1.1 (0x00007fa55c444000)
           librte_ring.so.1.1 => /home/apanda/e2d2/3rdparty/dpdk/build/lib/librte_ring.so.1.1 (0x00007fa55c242000)
           librte_eal.so.2.1 => /home/apanda/e2d2/3rdparty/dpdk/build/lib/librte_eal.so.2.1 (0x00007fa55bfe1000)
           librte_cmdline.so.2.1 => /home/apanda/e2d2/3rdparty/dpdk/build/lib/librte_cmdline.so.2.1 (0x00007fa55bdd8000)
           librte_cfgfile.so.2.1 => /home/apanda/e2d2/3rdparty/dpdk/build/lib/librte_cfgfile.so.2.1 (0x00007fa55bbd6000)
           librte_pmd_bond.so.1.1 => /home/apanda/e2d2/3rdparty/dpdk/build/lib/librte_pmd_bond.so.1.1 (0x00007fa55b9c4000)
           libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 (0x00007fa55b7ae000)
           libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007fa55b5aa000)
           libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007fa55b38d000)
           libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007fa55afe9000)
           /lib64/ld-linux-x86-64.so.2 (0x00007fa55ed87000)
           libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007fa55aceb000)
           librt.so.1 => /lib/x86_64-linux-gnu/librt.so.1 (0x00007fa55aae3000)


As you can see librte_pmd_i40e.so is missing from the list of files. Furthermore, using

$ LD_PRELOAD="../lib/librte_pmd_i40e.so" ./testpmd -c 0x1c00 -n 4 -w 82:00.0 -w 82:00.1 --file-prefix "send" -- -i
correctly enumerates the NICs.

I unfortunately do not how to fix the linker script as checked in, but wanted to report this bug in case someone has a fix.