In an upcoming CXL related changes to the aarch64 target QEMU, the legacy -drive

option only does not work to set rootfs image; see below Jonathan's suggestions:

This is a challenge to fix at qemu side because it is relying
on a bunch of old behavior.  For a while now legacy -drive parameters have been
split into parts that go in -drive and a separate -device entry
that covers the hardware - even with that though we'd need
to specify a bus as on arm64 the default for -drive is virtio-blk
which ends up I connected on the pcie bus.

Note this is just as broken if you use any pxb-pcie instances as
those have similar fixed assumption that you can only hang root ports
off them.

I think best solution is probably to stop use the old style

-drive file=root.img,format=raw,media=disk

and switch to fully expanded virtio solution along the lines of

-drive if=none,file=root.img,format=raw,media=disk,id=hd \
-device virtio-blk,bus=pcie.0,drive=hd

which should be fine on x86 and arm64 + any other architectures we
support in the future and will always bring the disk up as an RCiEP
on the main pcie root complex.

Jonathan

Author: Itaru Kitayama

run_qemu.sh

@@ -1858,7 +1858,9 @@ prepare_qcmd()
 		;;
 	esac
 
-	qcmd+=("-drive" "file=$_arg_rootfs,format=raw,media=disk")
+	qcmd+=("-drive" "file=$_arg_rootfs,format=raw,if=none,id=rootdisk,media=disk")
+	qcmd+=("-device" "virtio-blk,bus=pcie.0,drive=rootdisk")
+
 	if [ $_arg_direct_kernel = "on" ] && [ -n "$vmlinuz" ] && [ -n "$initrd" ]; then
 		qcmd+=("-kernel" "$vmlinuz" "-initrd" "$initrd")
 		qcmd+=("-append" "${kcmd[*]}")