[tlbuild] PPC builds

[Mojca Miklavec]

On Sat, 15 Feb 2020 at 16:18, Johannes Hielscher wrote:
> Am Sat, 15 Feb 2020 08:27:39 +0100 schrieb Mojca Miklavec:
>
> > You mention issues with GD and libpng. I have issues building those
> > on a regular aarch64 platform (using armbian)
>
> You run ./Build --enable-arm-neon=check?

BINGO! (And I'm sorry for the slightly delayed response, initially I
was more busy and didn't get around to connecting the device, then
forgot abut this not-so-high-priority issue.)

Karl, this was the command-line option I was missing to get the TeX
Live build work on aarch64.
I initially thought I was missing some libpng development headers, but
apparently the reason was elsewhere.

Is there any chance to somehow make this work out of the box without
extra flags?
(Even if not, just knowing this piece of information is helpful.)

> Back then some 2⅓ years ago,
> pulling the update of libpng and propagating this through the configure
> command line options, was the way Karl and me got TLbuild work on
> aarch64-linux (Armbian as well), as native build without dependency on
> system-provided libs/headers.
>
> This was a bit tedious to figure out in the first place, but since
> then, the platform is very well-behaved. See Build/source/README and
> the 2017-12-02 entry in Build/source/libs/libpng/ChangeLog . Since
> then, I set up build environments on three new aarch64-linux boxes
> (based on various Debian flavours, and Archlinux ARM), and it worked
> each time.
>
> To our luck, upstream sources were in a aarch64-friendly state already,
> and just had to be configured properly to use NEON. Dunno if this is as
> easy on ppc64.
>
> Best,
> Johannes

Thank you,
    Mojca