Re: error in testpmd when CONFIG_RTE_BUILD_SHARED_LIB=y

From: Thomas Monjalon <thomas.monjalon@6wind.com>
To: Bruce Richardson <bruce.richardson@intel.com>
Cc: Shreyansh Jain <shreyansh.jain@nxp.com>,
	john miller <john.miller@atomicrules.com>,
	dev@dpdk.org, "olivier.matz@6wind.com" <olivier.matz@6wind.com>
Subject: Re: error in testpmd when CONFIG_RTE_BUILD_SHARED_LIB=y
Date: Wed, 12 Apr 2017 12:25:34 +0200	[thread overview]
Message-ID: <1852173.LYJU7u7p34@xps13> (raw)
In-Reply-To: <20170412100521.GB20092@bricha3-MOBL3.ger.corp.intel.com>

2017-04-12 11:05, Bruce Richardson:
> On Wed, Apr 12, 2017 at 04:52:47AM +0000, Shreyansh Jain wrote:
> > From: Thomas Monjalon [mailto:thomas.monjalon@6wind.com]
> > > 2017-04-11 14:02, john miller:
> > > >
> > > > We are seeing an issue when running from the head of the master branch in
> > > dpdk-next-net and building with CONFIG_RTE_BUILD_SHARED_LIB=y.   When we run
> > > testpmd using  -d to point to our PMD we get this error
> > > >
> > > > EAL: Error - exiting with code: 1
> > > >   Cause: Creation of mbuf pool for socket 0 failed: Invalid argument
> > > >
> > > > This error occurs as a result of the rte mempool ops table having 0
> > > entries.  This table is populated from a call to rte_mempool_register_ops().
> > > This function gets called in rte_mempool_ring.c via the static initialization
> > > MACRO MEMPOOL_REGISTER_OPS and exists in librte_mempool_ring.so.  However
> > > this library is not loaded when the rte_eal_init() gets called so the static
> > > initializers are not yet loaded.
> > > >
> > > > I am requesting advice on the proper way to repair this.
> >  
> > "-d" the ring library (rte_mempool_ring) - just like any other shared lib.
> > 
> 
> I think this is a bug that should be fixed. The user should not need to
> have to specify a mempool driver just to get testpmd working, so I think
> the ring handler as default should be compiled in automatically so as to
> allow regular mempools to just work as before.

We thought about it when moving the mempool handler as a driver.
The common case when using shared libs, is to specify the lib directory
with -d or with CONFIG_RTE_EAL_PMD_PATH.

I am not sure we should make an exception for the mempool driver.
If it is built as a shared library, the only one able to link it is
the user (who knows where the file is).

> > This change was done recently to move ring handler into its separate drivers/mempool/ring directory. That also means it no longer is compiled into the librte_mempool.
> > 
> > > 
> > > We should just add a better error message if no mempool driver is available.
> > 
> > Yes, that is something to be improved.
> 
> This should be fixed by always having a mempool driver installed.

It is not a matter of having it installed but finding it in the right path.
A good error message suggesting -d would be OK I think.