[dpdk-dev] driver initialization in DPDK 2.0 built into a shared library.

[dpdk-dev] driver initialization in DPDK 2.0 built into a shared library.

[Polevoy, Igor]

Hi,
We are developing an application that uses DPDK PMD functionality .
We are using a linux shared library which contains the network packets processing code and it is statically linked with all the necessary DPDK libs.
The .so is loaded by the main program.
For the DPDK compilation we have added the -fPIC to the GCC options.

While it all worked fine with DPDK 1.6 where we had the rte_pmd_init_all method, in the 2.0 version the
drivers registration methods (PMD_REGISTER_DRIVER) are not called when the shared library is loaded.

Although, I can go along the lines of the rte_pmd_init all and manually call the driver registration, I'm concerned
that DPDK has other drivers initialization calls, and I don't actually know which are needed or could be needed and when.

Do you have any advice on that? What is the best way to resolve this issue?

Thank you
Igor.

Re: [dpdk-dev] driver initialization in DPDK 2.0 built into a shared library.

[Keunhong Lee]

Did you tried 'mk/rte_app.mk' to build you application?
Simply including -lrte_pmd_xxx may cause problem because
PMD_REGISTER_DRIVER uses 'init' attribute,
which is called before the 'main' function.
See the 'start-group' and 'whole-archive' linker options.

Keunhong.


2015-07-15 3:21 GMT+09:00 Polevoy, Igor <Igor_Polevoy@mcafee.com>:

> Hi,
> We are developing an application that uses DPDK PMD functionality .
> We are using a linux shared library which contains the network packets
> processing code and it is statically linked with all the necessary DPDK
> libs.
> The .so is loaded by the main program.
> For the DPDK compilation we have added the -fPIC to the GCC options.
>
> While it all worked fine with DPDK 1.6 where we had the rte_pmd_init_all
> method, in the 2.0 version the
> drivers registration methods (PMD_REGISTER_DRIVER) are not called when the
> shared library is loaded.
>
> Although, I can go along the lines of the rte_pmd_init all and manually
> call the driver registration, I'm concerned
> that DPDK has other drivers initialization calls, and I don't actually
> know which are needed or could be needed and when.
>
> Do you have any advice on that? What is the best way to resolve this issue?
>
> Thank you
> Igor.
>
>

Re: [dpdk-dev] driver initialization in DPDK 2.0 built into a shared library.

[Polevoy, Igor]

After linking the shared library using –whole-archive and –start-group and allowing for multiple definitions also with –z,muldefs I have the situation when init is called two times and I’m  getting the core created inside the tailqinitfn_rte_uio_tailq
(eal_common_tailqs.c:153).
Commenting out the log print does not help as the method still returns -1 and goes to the rte_panic.

Igor

From: Keunhong Lee [mailto:dlrmsghd@gmail.com]
Sent: Tuesday, July 14, 2015 11:42 AM
To: Polevoy, Igor
Cc: dev@dpdk.org
Subject: Re: [dpdk-dev] driver initialization in DPDK 2.0 built into a shared library.

Did you tried 'mk/rte_app.mk<http://rte_app.mk>' to build you application?
Simply including -lrte_pmd_xxx may cause problem because
PMD_REGISTER_DRIVER uses 'init' attribute,
which is called before the 'main' function.
See the 'start-group' and 'whole-archive' linker options.

Keunhong.


2015-07-15 3:21 GMT+09:00 Polevoy, Igor <Igor_Polevoy@mcafee.com<mailto:Igor_Polevoy@mcafee.com>>:
Hi,
We are developing an application that uses DPDK PMD functionality .
We are using a linux shared library which contains the network packets processing code and it is statically linked with all the necessary DPDK libs.
The .so is loaded by the main program.
For the DPDK compilation we have added the -fPIC to the GCC options.

While it all worked fine with DPDK 1.6 where we had the rte_pmd_init_all method, in the 2.0 version the
drivers registration methods (PMD_REGISTER_DRIVER) are not called when the shared library is loaded.

Although, I can go along the lines of the rte_pmd_init all and manually call the driver registration, I'm concerned
that DPDK has other drivers initialization calls, and I don't actually know which are needed or could be needed and when.

Do you have any advice on that? What is the best way to resolve this issue?

Thank you
Igor.

Re: [dpdk-dev] driver initialization in DPDK 2.0 built into a shared library.

[Bruce Richardson]

On Tue, Jul 14, 2015 at 06:21:33PM +0000, Polevoy, Igor wrote:
> Hi,
> We are developing an application that uses DPDK PMD functionality .
> We are using a linux shared library which contains the network packets processing code and it is statically linked with all the necessary DPDK libs.
> The .so is loaded by the main program.
> For the DPDK compilation we have added the -fPIC to the GCC options.
> 
> While it all worked fine with DPDK 1.6 where we had the rte_pmd_init_all method, in the 2.0 version the
> drivers registration methods (PMD_REGISTER_DRIVER) are not called when the shared library is loaded.
> 
> Although, I can go along the lines of the rte_pmd_init all and manually call the driver registration, I'm concerned
> that DPDK has other drivers initialization calls, and I don't actually know which are needed or could be needed and when.
> 
> Do you have any advice on that? What is the best way to resolve this issue?
> 
> Thank you
> Igor.
> 
You probably need to add the "no-as-needed" flag to your link command.

/Bruce

Re: [dpdk-dev] driver initialization in DPDK 2.0 built into a shared library.

[Zoltan Kiss]

On 14/07/15 19:21, Polevoy, Igor wrote:
> Hi,
> We are developing an application that uses DPDK PMD functionality .
> We are using a linux shared library which contains the network packets processing code and it is statically linked with all the necessary DPDK libs.
> The .so is loaded by the main program.
> For the DPDK compilation we have added the -fPIC to the GCC options.
>
> While it all worked fine with DPDK 1.6 where we had the rte_pmd_init_all method, in the 2.0 version the
> drivers registration methods (PMD_REGISTER_DRIVER) are not called when the shared library is loaded.
>
> Although, I can go along the lines of the rte_pmd_init all and manually call the driver registration, I'm concerned
> that DPDK has other drivers initialization calls, and I don't actually know which are needed or could be needed and when.
>
> Do you have any advice on that? What is the best way to resolve this issue?
>
> Thank you
> Igor.
>

I've seen a similar problem, but in a different setup. My app (OVS) 
links to ODP-DPDK statically, which then links to DPDK code statically. 
I found that the devinitfn_* functions are not called because OVS 
doesn't call directly into the DPDK library, only into ODP-DPDK. The 
workaround for me was to refer to those functions in the ODP-DPDK code:

#define PMD_EXT(drv)  extern void devinitfn_##drv(void);
PMD_EXT(bond_drv)
PMD_EXT(em_pmd_drv)
...

But there might be better solutions than that. This one is fragile, if 
you update DPDK you have to remember adding these references for new PMDs.

Zoli