How to boot OpenWRT FROM PXE?

I have downloaded OpenWRT files for PC from OpenWRT site . I have installed DHCP and TFTP (in my LAN) and can boot (other) kernels from them. Now I want to boot these OpenWRT files. I wrote in PXE config DEFAULT minimallinux SAY Now booting Minimal Linux... LABEL minimallinux MENU LABEL Minimal Linux KERNEL vmlinuz INITRD rootfs-squashfs.img.gz It boots, loads kernel, then loads image, then starts boot printouts and finaly crashes with kernel panic and reboots VFS:Cannot open root device "(null)" or unknown-block(0,0): error-6 Please append a correct "root=" boot option; here are the available partitions: Kernel panic - not syncing: VFS: Unable to mount root fs on unknown un-blokc(0,0) I also tried KERNEL vmlinuz APPEND initrd=rootfs-squashfs.img.gz boot=live toram=rootfs-squashfs.img.gz and some other combinations but failed. Any hints appreciated :)