Re: [Question/Issue] pkgconfig does not include dpdk/drivers libs

[Bruce Richardson <bruce.richardson@intel.com>]

On Thu, Aug 03, 2023 at 12:51:36PM +0000, Abhineet Pandey wrote:
>    Hi Bruce,
>    Thanks for taking a look at this.
>    Talking about the issues you pointed,
>    1. Absense of -lrte_bus_pci and similar flags
>    Even if I don’t give –static flag, I don’t see -lrte_bus_pci (and
>    -lrte_bus_vdev, -lrte_mempool_ring).
>    Attaching output,
>    PKG_CONFIG_PATH=dpdk/build/lib/pkgconfig pkg-config --libs libdpdk
> 
>    -Wl,--as-needed -L/home/nutanix/spdk/dpdk/build/lib -lrte_vhost
>    -lrte_security -lrte_reorder -lrte_dmadev -lrte_power -lrte_cryptodev
>    -lrte_compressdev -lrte_timer -lrte_hash -lrte_cmdline -lrte_pci
>    -lrte_ethdev -lrte_meter -lrte_net -lrte_mbuf -lrte_mempool -lrte_rcu
>    -lrte_ring -lrte_eal -lrte_telemetry -lrte_kvargs
>    Not sure if this is expected.

Yes, that is expected. For shared-library builds, the drivers are
dynamically loaded at runtime, rather than being linked directly to the
app. This allows drivers to be added/removed from an install without
breaking anything. To deploy DPDK to a platform, you only need copy over
the .so files you need for the hardware on that platform.

>    2. Missing constructor runs.
>    Got your point. I’m using pkg-config  0.27.1. Will check how to avoid
>    the automatic No Whole Archive thing. Still not sure about point 1
>    though.

I'd recommend installing pkgconf, or getting an updated pkg-config binary.

>    Regards,
>    Abhineet
> 
> 
>    From: Bruce Richardson <bruce.richardson@intel.com>
>    Date: Thursday, 3 August 2023 at 3:46 PM
>    To: Abhineet Pandey <abhineet.pandey@nutanix.com>
>    Cc: dev@dpdk.org <dev@dpdk.org>
>    Subject: Re: [Question/Issue] pkgconfig does not include dpdk/drivers
>    libs
> 
>    On Thu, Aug 03, 2023 at 09:15:11AM +0000, Abhineet Pandey wrote:
>    >    I’m consuming dpdk via spdk.
>    >    I was trying to use pkg-config for a Makefile that I’m writing,
>    >    Executing:
>    >
>    >    PKG_CONFIG_PATH=dpdk/build/lib/pkgconfig pkg-config --libs
>    --static
>    >    libdpdk
>    >    Output:
>    >    -Wl,--whole-archive -Wl,--no-whole-archive -Wl,--as-needed
>    -pthread
>    >    -L/home/nutanix/exact_spdk/spdk/dpdk/build/lib -l:librte_bus_pci.a
>    >    -l:librte_bus_vdev.a -l:librte_mempool_ring.a -l:librte_vhost.a
>    >    -l:librte_security.a -l:librte_reorder.a -l:librte_power.a
>    >    -l:librte_cryptodev.a -l:librte_compressdev.a -l:librte_timer.a
>    >    -l:librte_hash.a -l:librte_cmdline.a -l:librte_pci.a
>    -l:librte_ethdev.a
>    >    -l:librte_meter.a -l:librte_net.a -l:librte_mbuf.a
>    -l:librte_mempool.a
>    >    -l:librte_rcu.a -l:librte_ring.a -l:librte_eal.a
>    -l:librte_telemetry.a
>    >    -l:librte_kvargs.a -lrte_vhost -lrte_security -lrte_reorder
>    -lrte_power
>    >    -lrte_cryptodev -lrte_compressdev -lrte_timer -lrte_hash
>    -lrte_cmdline
>    >    -lrte_pci -lrte_ethdev -lrte_meter -lrte_net -lrte_mbuf
>    -lrte_mempool
>    >    -lrte_rcu -lrte_ring -lrte_eal -lrte_telemetry -lrte_kvargs -lm
>    -ldl
>    >    -lnuma
>    >    At a closer look, you’ll see -l:librte_bus_pci.a
>    -l:librte_bus_vdev.a
>    >    -l:librte_mempool_ring.a, but you won’t find corresponding
>    >    -lrte_bus_pci, -lrte_bus_vdev, -lrte_mempool_ring. This showed up
>    in my
>    >    use case as rte_mempool_ring has some functions which execute on
>    >    startup via __attribute__((constructor)), and they did not execute
>    thus
>    >    causing issues.
>    I think there are two separate issues you are flagging here.
>    1. Absense of -lrte_bus_pci and similar flags
>    2. Missing constructor runs.
>    For the former, the behaviour is exactly as expected. You have
>    specified
>    static linkage on the pkg-config commandline, so pkg-config is listing
>    out
>    the libraries to link against only in static form. With
>    -l:librte_bus_pci.a, where is no need for -lrte_bus_pci since the pci
>    bus
>    library is already linked in.
>    For the missing constructors, the issue is separate. That implies that
>    when
>    the static libs are linked, the constructors are not getting included.
>    Normally, this is done by specifying the --whole-archive flag to the
>    linker, but in your case above, that is immediately followed by
>    --no-whole-archive which counteracts it! I suspect you may have a bug
>    in
>    your pkg-config. By any chance are you using pkg-config 0.27? There is
>    known issue with it not linking static libs correctly, see note in [1]
>    /Bruce
>    [1]
>    [1]https://urldefense.proofpoint.com/v2/url?u=https-3A__doc.dpdk.org_gu
>    ides-2D23.07_linux-5Fgsg_sys-5Freqs.html-23compilation-2Dof-2Dthe-2Ddpd
>    k&d=DwIDaQ&c=s883GpUCOChKOHiocYtGcg&r=UaVZAw32qzYwqV0iyjkICkaNhB8peZhhE
>    JSs22LHVbI&m=NHXDGIxEa3NlLGmshhz7un6SMT4NlACKBYA39xVBj3VGki9GCytR-HAHnQ
>    i0cM4S&s=OSlZ0EizFQ8Xa1HkrPrAywHi_kuZHJHhTe48KKtL-AA&e=
> 
> References
> 
>    1. https://urldefense.proofpoint.com/v2/url?u=https-3A__doc.dpdk.org_guides-2D23.07_linux-5Fgsg_sys-5Freqs.html-23compilation-2Dof-2Dthe-2Ddpdk&d=DwIDaQ&c=s883GpUCOChKOHiocYtGcg&r=UaVZAw32qzYwqV0iyjkICkaNhB8peZhhEJSs22LHVbI&m=NHXDGIxEa3NlLGmshhz7un6SMT4NlACKBYA39xVBj3VGki9GCytR-HAHnQi0cM4S&s=OSlZ0EizFQ8Xa1HkrPrAywHi_kuZHJHhTe48KKtL-AA&e=