i've been meaning to test how much it costs to run GENERIC.MP on eg, an older UP system (sun4/sun4c). if it's a lot, maybe figure out a boot time patch to help. when i tested on sparc64, i couldn't observe any speed diff betweeen GENERIC and GENERIC.MP, so i just enabled MP in the base kernel, which also solved a problem on usIIIi systems - dual socket usIIIi are effectively NUMA, where some memory is attached it this CPU, and some the other. we hang on UP kernels in this setup, i'm not sure why or how exactly to interrogate the setup to determine ram to ignore. .mrg.