Re: About support for rtVAX300

[Johnny Billquist <bqt%update.uu.se@localhost>]

On 2013-01-11 22:50, Michael L. Hitch wrote:
> On Fri, 11 Jan 2013, Holm Tiffe wrote:
>
> > On the rtvax is a register for the TIL311 Display, I can write an
> > ~0xa to 0x201ffffe and see an 'A', with that I've tried to trace
> > the startup code a little, but I get lost in pmap_bootstrap() called from
> > locore.c.
> > On the very last instruction in pmap_bootstrap()
> >
> >            VM_FREELIST_DEFAULT);
> >        mtpr(sysptsize, PR_SLR);
> >        rpb.sbr = mfpr(PR_SBR);
> >        rpb.slr = mfpr(PR_SLR);
> >        rpb.wait = 0;   /* DDB signal */
> >
> >      *(int *)(0x201ffffe)=0xf-3; /* Holm */
> >
> >        mtpr(1, PR_MAPEN);
> >
> >         *(int *)vax_map_physmem(0x201ffffe,1)=0xf-4; /* Holm */
> > }
> >
> > Nothing happens anymore and I get a trap or something like this..
> > I never see that '4', regardless if I try vax_map_physmem or not.
> > Is vax_map_physmem() the right thing to this time?
>
>    vax_map_physmem() maps the whole page, so will return the virtual
> address of the page that contains 0x201ffffe, so you will be writing to
> 0x201ffe00 (if I've calculated the bits right).

I actually checked the code, since I was thinking the same thing, but I 
think not. The code at the end of vax_map_physmem looks like this:

        return addr | (phys & VAX_PGOFSET);

Where addr is the base for the page you got. phys is the requested 
address, which is masked down to just an offset within a page, and then 
merged with the base address. But I might be wrong...

        Johnny

--
Johnny Billquist                  || "I'm on a bus
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