Re: *Potential Spam* Re: Current kernel with http://gnats.netbsd.org/39965 and pmap patches

["Michael L. Hitch" <mhitch%lightning.msu.montana.edu@localhost>]

On Thu, 18 Dec 2008, Izumi Tsutsui wrote:

> I wrote:
>
> > I don't understand what XXX calculations in amiga_init.c do and
> > how they map PA of Sysmap (Sysptmap_pa) into VM_MAX_KERNEL_ADDRESS
> > in mmu040_setup() case... (it's a bit different from other m68k ports)
>
> Is this what those calculations intend?
> (though I'm still being confused a bit)

  I've been working with the amiga pmap for 14 years, and still get 
confused.  [It doesn't help that I only get into it every few years.]

  One thing that greatly confused me when I was doing these changes for 
the amiga was that some of the macros used in the calculations for the 
other m68k ports are 'incorrect'.  By that I mean that the values defined 
for the macros are correct and they result in the proper computed values, 
but the macros are only valid if the pagesize is 4K, and result in way 
wrong values for pagesize of 8K.  So the amiga computes things in a 
different manner, trying to be correct for either pagesize.

  On another note, I can't remember if I verified that the current amiga 
pmap worked on 68030 systems or not.  I think I had someone verify that, 
but my memory isn't that clear.

  I'll try to look over these changes, but I'm a bit busy at the moment 
and it'll take me a little while to remember how all this stuff works.

--
Michael L. Hitch                        mhitch%montana.edu@localhost
Computer Consultant
Information Technology Center
Montana State University        Bozeman, MT     USA