I just started to use OpenWRT as quest system using Qemu and I noticed that for the "malta" platform there is no way to separate "rootfs" for mips processor as there is for ARM virtualization. Do you have any indication/suggestion on how I could create a permanent storage for software I 'd like to install to customize the image? In particular, I would like to verify a service I wrote can run on it.
well malta-be has downloadable rootfs options. otherwise the simplest thing would be to use a buildroot... and populate ./files... ( place within the existing initramfs image )
if all your doing is testing software... then having a real rootfs is not so important... there are many options available to mount / access additional filesystems either locally or over a network then do your thing.
the non-be options do seem "stuck in legacy" from a cursory glance... so I dunno what the buildroot will let you do with those... gcc5 might even have some fancy quirks.