In LRP, the root volume is normally specified by the ROOT parameter in syslinux.cfg. However, this is not necessary as the rdev utility can be used on the newly created kernel to set an appropriate default inside the kernel itself. The kernel parameter ROOT overrides this value.

Likewise, the /linuxrc script could write to the file /proc/sys/kernel/real-root-dev the value of the real root device. For /dev/ram1, this would be 0x0101. The major and minor values can be gotten from a ls done on the file in /dev or by reading linux/Documentation/devices.txt in the Linux source code tree.