Hi there,
i think that the packages for arm_cortex-a9_vfpv3 are a bit outdated (e.g. wireguard_0.0.20190702-1_arm_cortex-a9_vfpv3.ipk build on Apr 19th).
For the R7800 (arm_cortex-a15_neon-vfpv4) you can find an actual package (wireguard_1.0.20200506-1_arm_cortex-a15_neon-vfpv4.ipk) - it was build on May 15th.
The older SoCs such as Armada XP and 370 only supports vfpv3-d16 while 385 and newer does complete vfpv3 and neon. This hampers performance of newer SoCs quite a bit and makes little sense not to split these since we already build vfpv3+neon binaries. While neon-vfpv4 exists, neon-vfpv3 doesn’t and for some reason it’s just called neon in GCC (which translates to arm_cortex-a9_neon in LEDE for this SoC family).
to keep my WRT1900ACS (Marvell Armada 385 88F6820) up to date, i have to change the arch from arm_cortex-a9_vfpv3 to arm_cortex-a9_neon, right?
Yes you can run NEON on that device, but, there are no bot generated NEON images. You could try changing to those bot NEON packages to see if it works, may have to force as a package / image mismatch is to be expected. I think as things stand right now, if you want the full meal deal, you need a build image with GCC options to your own specification. There are SIMD images off my avatar, but may not be what you are looking for in terms of baked in packages, also only 5.4 master images.
Ok, installed 19.07.3 and now the distfeeds.conf points to arm_cortex-a9_vfpv3-d16.
IMHO, it would have been good to build arm_cortex-a9_vfpv3 also for the guys who want to stick to 19.07.2 and earlier ... so that they have actual packages ...