question on symbol exports

Chris Friesen cfriesen at
Sat Feb 5 07:14:11 EST 2005

I've added the ppc64 list to the addressees, in case they are interested.

Marcelo Tosatti wrote:
> On Tue, Feb 01, 2005 at 04:50:16PM +0100, Arjan van de Ven wrote:

>>afaik one doesn't need to do a tlb flush in code that clears the dirty
>>bit, as long as you use the proper vm functions to do so. 
>>(if those need a tlb flush, those are supposed to do that for you

> Yep, and "proper VM function" is include/asm-generic/pgtable.h::ptep_clear_flush_dirty(),
> which on PPC flushes the TLB.

It turns out that to call ptep_clear_flush_dirty() on ppc64 from a 
module I needed to export the following symbols:


>>Also note that your code isn't dealing with 4 level pagetables.... And
>>pagetable walking in drivers is basically almost always a mistake and a
>>sign that something is wrong.

> Or a sign that the core kernel lacks helper functions :) 

Absolutely.  It'd be so nice if there was a simple va_to_ptep() helper 
function available.


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