s6-ftrigrd: fatal: unable to flush asyncout: Broken pipe
I do my cross-compilation tests using QEMU and I remember having this
kind of issue sometimes. I always blamed it on a race condition and a
slow QEMU emulation, without looking any futher.
s6-ftrigrd uses out-of-band message passing, which is badly specified,
leaves a lot of leeway for implementations to get it wrong, and will
only work when doing the exact right workarounds for the system you're
using. So, getting the sysdeps right is especially important here.
I know Buildroot cannot - for now, and I still hope this changes at
some point - use predefined sysdeps, or run qemu'd autodetection tests,
for cross-compilation. But you really do need to make sure that all your
sysdeps are right.
I don't have access to a MIPS system, so I can't be sure, but normally
Linux, the relevant sysdeps are:
no matter the arch. Please make sure those are the correct values you're
using when building skalibs.