Re: Porting AGL to BBAI32.

["Scott Murray" <scott.murray@xxxxxxxxxxxx>]

On Sat, 29 Apr 2023, Ulises Vega wrote:

> Hello everyone,
>
> I hope you are having a wonderful weekend!!!
>
> I'm porting AGL to bbai 32bits
>
> I'm basing my porting in agl_bbe.inc, agl_beaglebone.inc and
> agl_j721e-evm.inc all of them are in meta-agl/meta-bsp/conf/include
> starting out previously from the templates at meta-agl/templates/machine/
> for bbe and j721e-evm as suggested by Scott Murray in previous post I sent.
>
> I have the following questions. If somebody can help, that would be much
> appreciated.
>
> Ulises Vega
>
> 1.-
> The following parameter appears in both agl_bbe.inc, and agl_beaglebone.inc
>
> DISTRO_FEATURES:append = " agl-medium-arm-compiler"
>
> Should I use it for my porting?

Ideally yes.  It overrides a machine's DEFAULTTUNE to give a consistent
tuning for 32-bit ARM targets so that the shared state in Yocto will be
more reusable across targets and simplify potentially doing a binary
package feed.  There is some potential to impact performance on the
newer ARM cores from doing so, though it's likely not large.

> 2.-
> j721e-evm has a:
>
> DEFAULTTUNE:k3r5 = "armv7athf"
>
> 1a) I want to find out the appropriate tuning for bbai32?
> 1b) should I use k3r5 or any other parameter? I know it has neon but I
> don't know which version?
>
> I looked at this page
> https://en.wikipedia.org/wiki/Comparison_of_ARM_processors#ARMv7-A
> and this one https://www.ti.com/lit/ds/symlink/am5729.pdf?ts=1682760256454
> and
> https://git.yoctoproject.org/poky/plain/meta/conf/machine/include/arm/arch-armv7a.inc
>
> but I don't know which tune to use.

Given there does not seem to be a Beaglebone AI machine .conf in meta-ti,
I imagine you're writing one from scratch.  I'd advise starting with an
existing conf that is clearly using Cortex-A15 cores.  I see that
there's a am57xx.inc file in meta-ti-bsp that e.g. am57xx-evm.conf uses,
that may be a reasonable starting point to copy from.  Denys may be able
to give some direction here, since he is one of the meta-ti maintainers.

> 3.-
> In order to port AGL to bbai32  i want to know if the following layers are
> needed:
>
>     ${METADIR}/bsp/meta-sancloud \
>     ${METADIR}/bsp/meta-rtlwifi \
>
> I got them from the template of
> meta-agl/templates/machine/bbe/50_bblayers.conf.inc

No, they will not be required.

> 4.-
> In order to port AGL to bbai32 I wan to enable graphics.
>
>
> I saw two different configs for bbe PREFERRED_PROVIDER_virtual* are enabled
> but for bbe but not for beaglebone they are not .So what should I use for
> bbai32:

You will want to pull Denys' set of changes to update meta-ti that are in
master branch as of yesterday.  Those completely redo how TI graphics
support configuration works, and I believe will simplify things for you.

Since you seem to be working up the BB AI configuration yourself, one
thing I'll note is that we so far have tried to avoid carrying our own
machine definitions in meta-agl-bsp, so if your intent is to upstream
something for the BB AI then there'll need to be a discussion about
committing to maintenance.  Ideally you would aim for getting it into
meta-ti, though I suspect that it's not there already is perhaps
intentional, since AFAICT the hardware seems to have already been
orphaned in favor of the BB AI 64.  Denys may be able to provide some
guidance around this as well.

Scott



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