I've tried building it inside an i686 chroot with:

<pre>$ sudo libremakepkg -n parabola-i686</pre>
and this gives:
<pre>
INSTALL sound/usb/snd-usb-audio.ko
INSTALL sound/usb/snd-usbmidi-lib.ko
INSTALL sound/usb/usx2y/snd-usb-us122l.ko
INSTALL sound/usb/usx2y/snd-usb-usx2y.ko
INSTALL sound/x86/snd-hdmi-lpe-audio.ko
INSTALL virt/lib/irqbypass.ko
DEPMOD 4.19.8-gnu-1
-> Installing hooks...
/startdir/PKGBUILD: line 466: /startdir/linux.install.pkg: Read-only file system
==> ERROR: A failure occurred in package_linux-libre().
Aborting...
</pre>

related: https://lists.parabola.nu/pipermail/dev/2019-May/007207.html