We're testing a rewrite of the x86 VM system and invlpg is much less expensive than the alternative of flushing the entire TLB for temporary mappings. I've been using invlpg in the old VM system for a while but the code has to have tests for processor type.
I'd actually like to go further and only support processors that have the CPUID instruction (that includes the plain Pentium otherwise my home machine would need to be replaced). We could provide instructions for what to do if someone desperately wanted to run the system on deprecated hardware, it's not hard but I feel it's not worth keeping the support in the main tree. Also, I can't find the old AT&T Safari and Gateway Nomad laptops I kept around for testing 386 and 486 compatibility so we've no way to test on those any more. --jim On Sat Oct 29 15:08:57 EDT 2005, [EMAIL PROTECTED] wrote: > On Sat, Oct 29, 2005 at 11:08:18AM -0400, Russ Cox wrote: > > Is anyone out there using Plan 9 on 386 machines? > > I'm just wondering whether it's going to affect anyone > > if the default kernels assume they can use some of > > the 486 instructions (specifically INVLPG). > > I am not and for some things I'm working on, I've given > up and assumed a PentiumPro. That said, it would be > nice to retain support for older machines. > > It has been a while since I've looked at Plan 9's VM > system. How hard would it be to select an implementation > at run time? It isn't too hard to probe for these sorts > of things at boot. I suppose one could also make it a > compile-time option, but I'd be inclined to avoid that > since it could lead to a real mess if people decided that > they wanted to use other features down the road. > > Why the sudden interest in invlpg?
