Re: [dpdk-dev] [PATCH] config: disable iova phys for dpaa and 1588 for dpaa2

[David Marchand <david.marchand@redhat.com>]

On Wed, Oct 30, 2019 at 10:37 AM Nipun Gupta <nipun.gupta@nxp.com> wrote:
>
> Hi David,
>
> > -----Original Message-----
> > From: David Marchand <david.marchand@redhat.com>
> > Sent: Sunday, October 27, 2019 4:33 PM
> > To: Nipun Gupta <nipun.gupta@nxp.com>
> > Cc: dev <dev@dpdk.org>; Yigit, Ferruh <ferruh.yigit@intel.com>; Hemant
> > Agrawal <hemant.agrawal@nxp.com>; Sachin Saxena
> > <sachin.saxena@nxp.com>; Thomas Monjalon <thomas@monjalon.net>
> > Subject: Re: [dpdk-dev] [PATCH] config: disable iova phys for dpaa and 1588
> > for dpaa2
> >
> > On Fri, Oct 4, 2019 at 1:26 PM Nipun Gupta <nipun.gupta@nxp.com> wrote:
> > >
> > > IOVA_PHYS flag is not required in the DPAA config, thus disable it.
> > > Also, disable the 1588 timer support by default on DPAA2 platform
> > > due to the performance impact
> >
> > With this patch, we don't have a single target using the 1588 timer support.
> > This means that it will get broken in the future.
> >
> > Is this used?
>
> Yes, this is enabled when PTP client application is used. We have by default disabled it
> because it has performance implications. We enable it in our system testing from time to
> time basis.

Ok, but beware that, starting from now, we (maintainers) won't see
that the compilation gets broken with this feature enabled.
Hope you can catch issues quickly.


> > With this patch, the meson configuration is unaligned with the make
> > configuration.
>
> I am not sure if I get this. In meson build as you mentioned:
> - config/meson.build:dpdk_conf.set('RTE_LIBRTE_DPAA2_USE_PHYS_IOVA', true)
> - config/arm/meson.build: ['RTE_LIBRTE_DPAA2_USE_PHYS_IOVA', false]]
>
> And in Makefile:
> config/common_base: CONFIG_RTE_LIBRTE_DPAA2_USE_PHYS_IOVA=y
> config/defconfig_arm64-dpaa2-linuxapp-gcc:CONFIG_RTE_LIBRTE_DPAA2_USE_PHYS_IOVA=n
>
> And now we have:
> config/defconfig_arm64-dpaa-linuxapp-gcc:CONFIG_RTE_LIBRTE_DPAA2_USE_PHYS_IOVA=n
>
> Can you please let me know if I need to make any change for meson build.

You updated the configuration for the dpaa machine in make.
config/arm/meson.build: ['RTE_LIBRTE_DPAA2_USE_PHYS_IOVA', false]]
only applies to dpaa2.
So in meson, the dpaa machine still has RTE_LIBRTE_DPAA2_USE_PHYS_IOVA=y

>
> >
> > If I look before the patch:
> >
> > origin/master:config/meson.build:dpdk_conf.set('RTE_LIBRTE_DPAA2_USE_
> > PHYS_IOVA',
> > true)
> > origin/master:config/arm/meson.build:
> > ['RTE_LIBRTE_DPAA2_USE_PHYS_IOVA', false]]
> >
> > origin/master:config/common_base:CONFIG_RTE_LIBRTE_DPAA2_USE_PHY
> > S_IOVA=y
> > origin/master:config/defconfig_arm64-dpaa2-linuxapp-
> > gcc:CONFIG_RTE_LIBRTE_DPAA2_USE_PHYS_IOVA=n
> >
> > And in the history, I understand:
> > - option (with dpaa2 in the name) introduced and enabled for all
> > - later, disabled for dpaa2
> >
> > Does it mean the option can be removed?
>
> Here again, we use this option when running DPDK in Virtual Machine (Direct Assignment).
> By default this option is disabled, but for VM scenarios we use this option extensively.

I don't understand when or on which platform you want this enabled/disabled.


If this option is supposed to be disabled by default, then the value
in those files (below) should be changed to n/false.
config/common_base:CONFIG_RTE_LIBRTE_DPAA2_USE_PHYS_IOVA=y
config/meson.build:dpdk_conf.set('RTE_LIBRTE_DPAA2_USE_PHYS_IOVA', true)
doc/guides/nics/dpaa2.rst:- ``CONFIG_RTE_LIBRTE_DPAA2_USE_PHYS_IOVA``
(default ``y``)

And then, we end up in the same situation than described above with no
configuration referencing this option enabled.

Please clarify.


--
David Marchand