All devices are based upon the same SoC, the Marvell 88F6281 "Kirkwood". Klick on the "kirkwood"-tag to see other devices based on this SoC.
After setting the basic system:
''echo 'CONFIG_TARGET_kirkwood=y' > .config"
you must configure the kernel with "make kernel_menuconfig"
From there, select the appropriate device from System Type → Marvell Kirkwood Implementations (Marvell GuruPlug Reference Board works for the GuruPlug Server Standard).