Re: [PATCH] fix ppc ioremap prototype

[ebiederm@xmission.com (Eric W. Biederman)]

Linus Torvalds <torvalds@osdl.org> writes:

> So clearly ioremap() has to work for other buses too.
> 
> I think that in the 2.7.x timeframe, the right thing to do is definitely:
>  - move towards using "struct resource" and "ioremap_resource()"
>  - make resource sizes potentially be larger (ie use "u64" instead of 
>    "unsigned long")
> 
> This is actually a potential issue already, with 64-bit PCI on regular 
> PC's. We don't handle it at all right now (the PCI probing will just not 
> create the resources), and nobody has complained, but clearly the 
> RightThing(tm) to do eventually is to make sure this all works cleanly.
> 
> I just don't think it's worth worrying about in 2.6.x right now, since it 
> doesn't matter for anybody. 

But it does.  There are at least some embedded ppc people who are actually
using 64bit physical addresses with a 32bit virtual address space.    

And this has come up in a few other times, as well.

A big question is how much of a problem this will be for later revs of
2.6.x.  I would even enable 64bit resources on an Opteron box and not
loose memory if I could be certain a 32bit kernel that people are
using temporarily would work.

So is there any reason to delay making resources a 64bit quantity?

Eric