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Re: [PAE support] Types + cosmetic fixes

On Tue, 23 Feb 2010 11:41:17 +0000, Andrew Doran <> 
> On Mon, Feb 22, 2010 at 10:25:35AM +0100, Jean-Yves Migeon wrote:
>> Opinions welcomed.
> I would like to see paddr_t and related types always be 64-bit,
> of whether the kernel is PAE enabled.  If not we effectively create a new
> platform.

Yep, i386-pae. IMHO, modules cannot be "safely" shared between PAE and

>  Do you envision any compatibility problems with userspace
> applications from this change?

Typical userspace applications, no. However, I suspect that programs like
crash(8) or libkvm would be affected by such a change. As well as those
reading stuff directly in kmem.

There is much more work for in-kernel code though; for example, iterating
through the PDs/PTs is not as easy as iterating in a paddr_t array
(consider a 64-bits paddr_t with a non-PAE kernel). We would have to split
pd_entry_t from paddr_t, which is currently not the case.

Maybe there will be overhead by using 64 bits variables for paddr_t too; I
don't know.

Why would you like to have paddr_t as always being 64 bits :) ?

Jean-Yves Migeon

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