[Buildroot] [PATCH 1/1] package/rpi-userland: add support for aarch64 build

[Yann E. MORIN <yann.morin.1998@free.fr>]

Christian, All,

On 2020-08-19 13:54 -0700, Christian Stewart spake thusly:
> On Tue, Aug 18, 2020 at 1:16 PM Yann E. MORIN <yann.morin.1998@free.fr> wrote:
> > > In the userland commit you link just above, they disable some things
> > > when targeting ARM64. We set ARM64 correctly in this patch with
> > > -DARM64=ON if BR2_aarch64, so this addresses everything correctly.
> >
> > So, this would, amongst others, not build:
> >
> >   - MMAL, so no low-level programming,
> >
> >   - interface/khronos, so no OpenGL EGL/GLES, no OpenVG,
> >
> >   - middleware/openmaxil, so no OpenMAX
> >
> > Unless I'm missing something non-obvious, I do not see how that can be
> > irrelevant...
> 
> Of course, not having everything is not irrelevant. However, this is
> something we expect the rpi-userland developers to address, not the
> Buildroot developers, correct?

Right, but the package in Buildroot still declares providing libegl,
libgels, vg, and max, which is clearly wrong in this case.

With just your patch, the package would still advertise providing those,
but they would not be built. Any pacjage that "just" needs a GL/GLES
provider (and has ptherwise no requirement on the arcitecture) would
fail to build.

That is what was pointed out in the first review (which I already
pointed to):

    http://lists.busybox.net/pipermail/buildroot/2020-January/271588.html

... which already had a proposal patch to fix the provider side of the
package, and also identifies all the delta between what is installed for
arm and for aarch64.

> As far as I can tell, adding this patch will install the tools that
> the rpi developers currently have deemed compatible with aarch64. This
> is vcgencmd and others. This basically would add early support for
> aarch64 to rpi-userland in Buildroot. Although not everything is
> there, installing the package with the parts that are compatible with
> that arch makes sense, right?

No, see above about the GL and stuff provider.

> As an example: I was writing a package which adds support for the
> argon one fan controller for pi 4. It added a dependency for
> rpi-userland for the vcgencmd command. I wrote this patch so that
> vcgencmd and the package will be installed correctly, and also so that
> my package which depends on RPI_USERLAND, could also build and be
> installed. Everything works as expected.
> 
> Other packages that depend on the arm-only binaries should already
> have BR2_arm dependency anyway, correct?

Not necessarily: packages that need a EGL/GLES provider could be
enabled, and they have no idea about arm or aarch64 (or even other
archs).

Regards,
Yann E. MORIN.

> Best regards,
> Christian Stewart

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