RE: Probing the expected state/support of DPDK@armhf

["Juraj Linkeš" <juraj.linkes@pantheon.tech>]

> -----Original Message-----
> From: Christian Ehrhardt <christian.ehrhardt@canonical.com>
> Sent: Wednesday, November 10, 2021 8:48 AM
> To: Ruifeng Wang <ruifeng.wang@arm.com>
> Cc: Jan Viktorin <viktorin@rehivetech.com>; dev <dev@dpdk.org>; Luca
> Boccassi <bluca@debian.org>; Juraj Linkeš <juraj.linkes@pantheon.tech>;
> Honnappa Nagarahalli <Honnappa.Nagarahalli@arm.com>; nd <nd@arm.com>
> Subject: Re: Probing the expected state/support of DPDK@armhf
> 
> On Tue, Nov 9, 2021 at 8:17 AM Ruifeng Wang <Ruifeng.Wang@arm.com>
> wrote:
> >
> > > -----Original Message-----
> > > From: Christian Ehrhardt <christian.ehrhardt@canonical.com>
> > > Sent: Monday, November 8, 2021 8:32 PM
> > > To: Jan Viktorin <viktorin@rehivetech.com>; Ruifeng Wang
> > > <Ruifeng.Wang@arm.com>; dev <dev@dpdk.org>
> > > Cc: Luca Boccassi <bluca@debian.org>
> > > Subject: Probing the expected state/support of DPDK@armhf
> > >
> > > Hi,
> > > I wanted to ask about the current state of DPDK@armhf (not arm64,
> > > that seems fine AFAICS).
> > > Since there are too many arms today, I mean armhf as in [0].
> > I think armhf in question refers to armv7.
> >
> > >
> > > What I see when building DPDK 21.11 is
> > > 2973 ../config/meson.build:364:1: ERROR: Problem encountered: Number
> > > of CPU cores not specified.
> > >
> > > Right now this seems to be broken the same everywhere - Suse [1],
> > > fedora [2], Debian/Ubuntu [3]
> > Looks like this happens with native build on armv7 machine. RTE_MAX_LCORE
> is not set for the build.
> 

What do we want to do with armv7 native build, Ruifeng? For aarch64, we detect which machine we're building on and we set everything accordingly, unless the generic build is enabled. Do we want to add support for just the generic build for armv7 (i.e. regardless of what's set in -Dplatform)? What values of RTE_MAX_LCORE and RTE_MAX_NUMA_NODES make sense for an armv7 generic build?

> Thanks for the hint,
> just FYI using the newer -Dplatform=generic without specifying the machine as
> we did in the past yields the same issue.
> I understand that every custom built project needs it's little special twist, but
> that (ask for the lowest common denominator) is exactly what generic builds in
> Distributions will need.
> 
> 
> > > I'm not asking for a fix for this particular issue (although I guess
> > > people would be happy), but more about the general state of DPDK@armhf.
> > >
> > > Debian and Ubuntu used to build it on armhf as well, but over the
> > > recent years I feel (no hard data) that usage there was next to none.
> > >
> > > OTOH Thomas said that recently people cared about armv7 [4]
> > >
> > > My suggestion would be to disable the build on armhf in
> > > Debian/Ubuntu
> > > (+elsewhere?) until it reaches a more stable phase and real use-cases.
> > > But maybe I missed some use-cases, therefore I wanted to reach out
> > > to the mailing list to probe for more opinions on this.
> > I'm not aware of amount of users that using DPDK on armv7. But [4] suggests
> that there is real use case.
> > I think the build on armhf does have value. It helps to maintain
> > general status on armv7. That is one of the reason why user [4] can enable
> armv7 cross compile smoothly.
> > I suggest to keep the build and fix the failure.
> >

That patch actually uses the aarch64 generic config with armhf compiler, so it's not really an armv7 build. I'll need to weigh in on that one.

> > >
> > > Thanks for your thoughts on this in advance!
> > >
> > > P.S. If it is meant to work and be supported, then we will need a
> > > fix for that
> > Hi Juraj,
> > Can you have a look at the issue?
> >
> > >
> > > [0]: https://wiki.debian.org/ArmHardFloatPort
> > > [1]:
> > > https://build.opensuse.org/public/build/home:bluca:dpdk/openSUSE_Fac
> > > to
> > > ry_ARM/armv7l/dpdk/_log
> > > [2]:
> > > https://build.opensuse.org/public/build/home:bluca:dpdk/Fedora_35/ar
> > > mv
> > > 7l/dpdk/_log
> > > [3]: https://launchpadlibrarian.net/567810935/buildlog_ubuntu-jammy-
> > > armhf.dpdk_21.11~rc1-1u~ppa1_BUILDING.txt.gz
> > > [4]:
> > > https://patches.dpdk.org/project/dpdk/patch/20210610111839.7481-1-
> > > s.chandrakant@globaledgesoft.com/
> > >
> > > --
> > > Christian Ehrhardt
> > > Staff Engineer, Ubuntu Server
> > > Canonical Ltd
> 
> 
> 
> --
> Christian Ehrhardt
> Staff Engineer, Ubuntu Server
> Canonical Ltd