[parisc-linux] arch/parisc/kernel/realmode_setup.c Question
Tue, 16 Nov 1999 07:02:29 -0700
Frank Rowand wrote:
> Alex deVries wrote:
> > On Mon, 15 Nov 1999, Frank Rowand wrote:
> > > You don't get to choose. The PDC is either 32 bit or 64 bit. It's not
> > > a question of what mode the OS is running in, but what the PDC was
> > > compiled for.
> > Hm. I'm pretty sure that a 32 bit version of HPUX has run on that box as
> > well, so wouldn't that mean that it'd have to be a 32 bit PDC?
> > - Alex
> Nope. The OS has to figure out what type of PDC it is calling, and properly
> marshall the arguments for the call.
Time for me to show off my ignorance again. :) As I understand it, the PDC is
firmware, which all the CPU (in a multiple CPU box) share. I know that when
I installed 11.X on this C200 that I was given the choice to install it in 32
64 bit mode. Does this mean the install disk updates the PDC firmware to boot
into either 32-bit or 64-bit mode?
Also looking at the PSW definition for the W bit on page 2-7 and
page 2-8 of PA-RISC 2.0 Architecture by Gerry Kane:
W: Wide 64-bit address formation enabled. When 1, full 64-bit-offset
is enabled. When 0, addresses are truncated to 32-bit offsets, for
with existing PA-RISC 1.0 and 1.1 applications.
From PIM dumps, I know all the registers are 64 bit, and the PSW is also 64 bit
this C200.. So it looks like I should be able to switch between 32-bit and
changing the W bit in the PSW?
P.S. I will try to query the PDC_MODEL as you suggested as in a previous email
in this thread and post the result when I get home tonight.