MMap function

Aaron J. Grier aaron at frye.com
Thu Mar 21 18:18:24 UTC 2002


On Thu, Mar 21, 2002 at 09:20:57AM +0100, VALETTE Eric wrote:

> Aaron J. Grier wrote:
> > RTEMS has no virtual memory subsystem, and the filesystems are usually
> > in-memory.  so no mmap() in RTEMS.
> 
> This is not totally accurate. pc386 BSP has virtual memory turned on
> (with of course a 1-1)  mapping. The reason is that there is no way
> non-using the mmu to mark *only* portion of physical address space non
> cacheable (think about PCI configuration space registers access).

<slaps head> of course...  do other processors (thinking of powerPC and
MIPS) do similar things with their MMUs when running RTEMS?

-- 
  Aaron J. Grier  |   Frye Electronics, Tigard, OR   |  aaron at frye.com
     "In a few thousand years people will be scratching their heads
       wondering how on earth the first computer was invented and
          bootstrapped without a prior computer to do it with."
                    --  Chris Malcolm, on comp.arch



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