SBus UltraSparc units don't poweroff when linux kernel ends, and return to Prom prompt where you have to type "power-off" command. (PCI UltraSparc as U5, U10... handle correctly this function) The prom_halt() function sends an "exit" command to Prom. The new function prom_poweroff() sends "SUNW,power-off" This patch is for sparc linux 2.4 (2.4.17,2.4.19 are known to work) It has been included in 2.4.20.