jat@xavax.com (John Tamplin) (02/11/91)
I have just grabbed the newly-freed Mach 3.0 micro-kernel and I am interested in a MC88100/88200 port of the machine dependent portion. If anybody has already done this (and is willing to give it out), I would definitely be interested. I have the Usenix Winter 90 tutorials on Mach (including the 68030 pmap stuff), but I have some questions. 1) TLB invalidations: since any 88100 can access any 88200, is there any reason to postpone invalidates? It seems that once a processor decides to invalidate a range, that cpu could write invalidate commands to all 88200's which share that memory (after gaining a cmmu semaphore). 2) Kernel address space: as far as I can tell, there is not any need to access the kernel pmap from user mode. On the 88200, there are separate translation trees for supervisor and user modes. If kernel access from user mode is not required, this would save having to copy the kernel segment entries into every thread's pmap. 3) software vs hardware pmaps: I am a bit confused about what is needed in this area, as the sample pmap code (68030) returns PMAP_NULL for software pmaps (size!=0 to pmap_create). Can someone explain what is required of a software pmap, what it is for, etc? -- John Tamplin Xavax jat@xavax.COM 2104 West Ferry Way ...!uunet!xavax!jat Huntsville, AL 35801