On Wed, Jun 01, 2005 at 11:06:28AM +0200, Jochen Kunz wrote:
> On Tue, 31 May 2005 23:22:11 -0700
> Chuck Silvers <chuq@chuq.com> wrote:
> 
> [D390]
> > > Is this a big task to add that support? 
> > different TLB handling,
> Yes, obviously. As I understand it (my knowldege in the VM area is very
> limited) PA-2.0 TLBs / MMU are a "linear extension" from 32 bit to 64
> bit. It is possible to run code in a 32 bit space on a PA-2.0 CPU so
> that the code still sees a PA-1.1 environment.
> 
> > different busses.
> To simplify: There are two generations of PA-2.0 machines: The early
> machines with GSC bus (and optional PCI) and those with PCI only. The
> early machines are quite similar to already supported machines. I
> suspect that we can support things like the D390, C240, C360, ... very
> fast once the TLB / pmap(9) stuff is done. The newer PCI only machines
> will need support for the newer PCI host bridges. This shouldn't be
> hard. I already have a C240 (old with GSC) and a B2000 (new PCI only)
> PA-2.0 machines to work on. Unfortunately I am no VM guru, so I have to
> leave this exercise to someone else.
> 
> > that model at least has firmware that can run in 32-bit mode,
> > so we won't need a 64-bit kernel to make it go.  at least,
> > I remember running 32-bit hpux on one some years back.
> I talked to a HP-PA Linux developer last year at the LinuxTag. He toled
> me that most PA-2.0 machines support 32 firmware / kernel. Only a few
> "server machines" are 64 bit only.
> 
> > but it'll be a fair bit of work.
> OpenBSD (mickey@) has done it. Maybe we can get some code from there?

yes, all of this is true, but someone still has to do the work.
the worst problem will be that our hppa pmap is completely different from
openbsd's, so the openbsd code will be no help with getting that working.

-Chuck