Upon the boot of l4linux iso image using QEMU, I got the following:
vmlinuz | RAMDISK: ext2 filesystem found at block 0
vmlinuz | RAMDISK: Loading 3072KiB [1 disk] into ram disk... done.
vmlinuz | EXT4-fs (ram0): couldn't mount as ext3 due to feature
incompatibilities
vmlinuz | EXT4-fs (ram0): mounting ext2 file system using the ext4
subsystem
vmlinuz | EXT4-fs (ram0): mounted filesystem without journal. Opts:
(null)
vmlinuz | VFS: Mounted root (ext2 filesystem) on device 1:0.
vmlinuz | Freeing unused kernel memory: 144K (00709000 - 0072d000)
vmlinuz | Clocksource tsc unstable (delta = 3346692958 ns)
vmlinuz | /bin/sh: can't access tty; job control turned off 

I disabled ACPI and power management options also.
I have included init=/bin/sh in l4linux.cfg script. Still the linux command prompt doesn't appear via l4linux launch.

The script is below:
//l4linux.cfg:

L4.default_loader:start({}, "rom/vmlinuz mem=64M console=ttyLv0 l4x_rd=rom/ramdisk-x86.rd root=1:0 ramdisk_size=4000 init=/bin/sh");