[dpdk-dev] [PATCH v5 2/4] build: add arm32 meson build flags

[Jerin Jacob]

On Wed, Jul 8, 2020 at 2:14 AM Honnappa Nagarahalli
<Honnappa.Nagarahalli at arm.com> wrote:
>
> <snip>
>
> > Subject: Re: [dpdk-dev] [PATCH v5 2/4] build: add arm32 meson build flags
> >
> > On Mon, Jul 6, 2020 at 1:59 PM Juraj Linkeš <juraj.linkes at pantheon.tech>
> > wrote:
> > >
> > > Base the flags on config/defconfig_arm-armv7a-linuxapp-gcc.
> > > Omit driver flags which can be built on arm32.
> > >
> > > Signed-off-by: Juraj Linkeš <juraj.linkes at pantheon.tech>
> >
> > Hi Juraj,
> >
> > Not strictly specific to this patch. Just to understand, How armv7 support has
> > been used?
> I do not know how armv7 support is being used. I have not heard of anything so far.
>
> In this patch arm32 is actually referring to aarch32.
>
> > - Is it for Running arm32 program on arm64 machines?
> I am not sure if anyone would run armv7 binaries on arm64 machines. I would think they will at least go through a re-compilation (to aarch32) and test phase.
>
> > - Is it for Native DPDK support from arm32. If so, What kind of PMD supports
> > native arm32 DPDK?
> Yes, this is for DPDK on aarch32 support. We do not have any plans to enable any PMD for aarch32. The current goal is to make sure that the code compiles for aarch32. Internally, we have validated few test cases for the libraries.

One thing is lack of PMD support and other is lack  PCI HW support for
armv7 machines in general.


>
> >
> > Or some other use case?
> >
> > I would like to understand the arm32 use case, so we can review it at that
> > angle.
>
> I believe armv7a compilation is not supported in meson. Do you have any thoughts? Do you plan to maintain the support for armv7a?

Armv7 is maintained by:
ARM v7
M: Jan Viktorin <viktorin at rehivetech.com>
M: Ruifeng Wang <ruifeng.wang at arm.com>
F: lib/librte_eal/arm/

My only concern is if there is no REAL use case for armv7 in DPDK, May
it is not worth to add a lot of code and make it complicated for
arm64.
At a minimum, If we are planning to add armv7 support then please
split config/arm/meson.build file as two for arm64 and armv7.