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
> 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