dms@mit-hermes.arpa (David M. Siegel) (02/02/86)
I was wondering if physical memory is mapped into a portion of the system address space? In other words, is the VAX 750's CMI main memory bus mapped into some system address space so that physical memory locations can be conviently used by either the kernel or a user? I guess the answer to this question lies in how the Sysmap is setup? Thanks, -Dave
chris@umcp-cs.UUCP (Chris Torek) (02/02/86)
In article <2134@brl-tgr.ARPA> dms@mit-hermes.arpa writes: > I was wondering if physical memory is mapped into a portion of the > system address space? Physical memory has physical addresses, sure. But there is no really easy direct way to get at physical memory once you go into mapped mode. > I guess the answer to this question lies in how the Sysmap is setup? Yes, though now you are speaking of specific kernel code, not of the Vax architecture itself. There is no one place in Sysmap that maps all of physical memory, but you can get at it a little bit at a time by creating a map, dropping it into locore.s, and using *(int *)mymap = btop(physaddr) | PG_V | PG_KW; mtpr(TBIS, vmymap); `Just like vax/mem.c.' -- In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 1415) UUCP: seismo!umcp-cs!chris CSNet: chris@umcp-cs ARPA: chris@mimsy.umd.edu