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Re: [PAE support] Types + cosmetic fixes

On 02/23/10 20:15, Manuel Bouyer wrote:
> On Tue, Feb 23, 2010 at 04:57:55PM +0100, Jean-Yves Migeon wrote:
>> Yep, i386-pae. IMHO, modules cannot be "safely" shared between PAE and
>> non-PAE.
> Yes. And I don't think making paddr_t 64bits unconditionally would
> make them magically compatible for modules. There would be other issues.

Should there be a "machine" (uname -m) defined with the following strings?


>> 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.
> Sure, you can't change the hardware to make the formats the same :)
> I don't know if anything outside kernel tries to read the PTE though.

I am more worried about parts of code which happily use paddr_t as pd_entry_t (they should be limited to pmap though).

But this doesn't tell me: should I go the "typdef uint64_t paddr_t" route? This may have unexpected overhead (which I cannot assess), and might consume extra stack/register just to store bytes which will never be used in non-PAE situation.

Jean-Yves Migeon

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