On Fri, Apr 15, 2005 at 11:20:54AM +0200, Dominique Quatravaux wrote: > Just out of curiosity, is there any practical interest in going 64bit on > Cobalt besides the fun of it? Second hand Cobalt MIPS hardware is available fairly cheaply so it's being used by various Linux developers for doing development work, including 64-bit work. > One cannot possibly squeeze more than 4 Gb of RAM into a Cobalt box right? No, the limit is significantly less. 64-bit kernels are advantagous if - running N32 or N64 software is desired - anything that takes advantage of 64-bit registers or the 32/32 fpr model - software is using large amounts of virtual address space. Process size is limited to 2GB which is tight for some of todays codes which do their I/O by memory mapping files. - and of the course there is the "more inches" factor ;-) > And doesn't 64 bit mode have costs of its own (doubled i-fetch bandwidth > for starters)? Fortunately not double and caches will further blurr the picture - but on a system with a 32-bit processor and memory bus there will be very noticable impact. We're using a bunch of tricks to keep the overhead under control. Ralf
