[parisc-linux] PDC calls on the C3000

Matthew Wilcox willy@thepuffingroup.com
Mon, 17 Jan 2000 13:34:21 -0500

On Mon, Jan 17, 2000 at 10:02:59AM -0800, Grant Grundler wrote:
> I'm thinking the inconsistency is possibly a firmware "bug" where either
> the C360 or C3000 isn't behaving "right". Can anyone comment on what
> the expected behavior is?

I would class it as a bug, but I just needed a workaround for the
next month or two :-)  BTW, the same thing happens on mkp's J5000.

> > 	0xffff'ffff'c0xx'xxxx
> > becomes
> > 	0x0000'0000'00xx'xxxx
> > and now PDC is happy, and so am I.
> This is where the hair on the back of my neck went up.
> The problem is on L-class and N-class machine we have
> I/O and memory addresses which are > 4GB. And PDC will really
> be confused on those platforms.

That won't be a problem.  The tophys macro is used to convert kernel
virtual addresses into physical addresses.  The kernel isn't going to
take more than 1GB of ram for its data segment :-)

We're not applying this macro to any other data type, don't worry.