RE: [RFC/PATCH] pfn_valid() more generic : intro[0/2]

From: Luck, Tony <tony.luck_at_intel.com>
Date: 2004-10-06 16:33:28
>ia64's ia64_pfn_valid() uses get_user() for checking whether a 
>page struct is available or not. I think this is an irregular 
>implementation and following patches
>are a more generic replacement, careful_pfn_valid(). It uses 2 
>level table.

It is odd ... but a somewhat convenient way to make check whether
the page struct exists, while handling the fault if it is in an
area of virtual mem_map that doesn't exist.  I think that in practice
we rarely call it with a pfn that generates a fault (except in error
paths).

How big will the pfn_validmap[] be for a very sparse physical space
like SGI Altix?  I'm not sure I see how PFN_VALID_MAPSHIFT is 
generated for each system.

Why do we need a loop when looking in the 2nd level?  Can't the
entry from the 1st level point us to the right place?

-Tony
-
To unsubscribe from this list: send the line "unsubscribe linux-ia64" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Received on Wed Oct 6 02:33:55 2004

This archive was generated by hypermail 2.1.8 : 2005-08-02 09:20:31 EST