Making an x86-image that's able to mount partitions on non-AHCI drives

OK helpful LEDE people:

here's what I want to do:

  • Make LEDE boot from HP Smart Array RAID logical 'disk'.

What I've achieved so far:

  • Created a patch for buildroot to package the right drvier for this controller called hpsa.ko into kmod-hpsa.ipk
  • Select 'y' in menuconfig so above ipk lands in the rootfs
  • Kernel boots but does not find any disks because hpsa.ko is on the rootfs, not in the kernel nor in a initramfs.

Problem / Challenge:

  • I could compile the hpsa driver right into the kernel -> but how would I do that? Semantics with buildroot's menuconfig (m==module, y==lands as module in rootfs) do not match those known from kernel menuconfig (y==compiled into kernel)
  • I could employ an initramfs.
    ** I found the menuconfig option to build an initramfs, but that seems to be tailored to get booted via tftp, not from disk (well it probably doesn't contain a bootloader so this can be expected...)
    ** If initramfs is enabled in menuconfig, the resulting combined-* images still contain a grub config that says initrd=no

Any ideas on how to do either one of the above or maybe find a 3rd way? Thanks a lot in advance!