Sparc-based hardware is divided into a number of different subarchitectures, identified by one of the following names: sun4, sun4c, sun4d, sun4m, sun4u or sun4v. The following list describes what level of support may be expected for each of them and what machines they include. sun4, sun4c, sun4d These subarchitectures include some very old 32-bit machines, which are no longer supported. For a complete list please consult the wikipedia SPARCstation page at Wikipedia SPARCstation page. sun4m sun4m is the only supported 32-bit subarchitecture (sparc32). Most popular machines belonging to this class are Sparcstation 4, 5, 10 and 20. Note that symmetric multiprocessing (SMP), that is the ability to run processes on multiple processors, is not supported on this hardware, due to stability problems with such configurations. Available uniprocessor (UP) sparc32 kernel will boot fine on multi-processor machines, however it will not activate and use more than one CPU. sun4u This subarchitecture includes all 64-bit machines (sparc64) based on the UltraSparc processor and its clones. Most of the machines are well supported, even though some might experience problems with booting from CD due to firmware or bootloader bugs (this problem may be overcome by using netbooting). Use the sparc64 or sparc64-smp kernel in UP and SMP configurations respectively. sun4v This is the newest addition to the Sparc family, which includes the machines based on the Niagara multi-core CPUs. At the moment such CPUs are only available in T1000 and T2000 servers by Sun, and are well supported. Use sparc64-smp kernel. Note that Fujitsu's SPARC64 CPUs used in PRIMEPOWER family of servers are not supported, due to lack of support in the Linux kernel. Most graphics options, commonly found on Sparc-based machines, are supported. X.org graphics drivers are available for sunbw2, suncg14, suncg3, suncg6, sunleo and suntcx framebuffers, Creator3D and Elite3D cards (sunffb driver), PGX24/PGX64 ATI-based video cards (ati driver), and PermediaII-based cards (glint driver). To use an Elite3D card with X.org you additionally need to install the afbinit package, and read the documentation included with it on how to activate the card. It is not uncommon for a Sparc machine to have two graphics cards in a default configuration. In such a case there is a possibility that Linux kernel directs its output to the card, different from the one initially used by the firmware. The lack of output on the graphical console may then be mistaken for a hang (usually the last message seen on console is 'Booting Linux...'). One possible solution is to physically remove one of the video cards. Also, if graphical output is not required or desired, serial console may be used as an alternative.