lkml.org 
[lkml]   [2007]   [Apr]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [patch 20/20] Add apply_to_page_range() which applies a function to a pte range.
On Wed, Apr 04, 2007 at 11:52:57PM -0700, Jeremy Fitzhardinge wrote:
> Matt Mackall wrote:
> >> +/*
> >> + * Scan a region of virtual memory, filling in page tables as necessary
> >> + * and calling a provided function on each leaf page table.
> >> + */
> >>
> >
> > But I'm not sure what the use case is that wants filling in the page
> > table..? If both modes really make sense, perhaps a flag could unify
> > these differences.
> >
>
> Well, two reasons:
>
> One is the general one that if you're traversing ptes then they need to
> exist to traverse them (for example, if you're creating new mappings).
> Obviously if you want to just visit existing mappings, then
> instantiating new pagetable is not the right thing to do (and I could
> make use of this too).
>
> The other is that there are various places in the Xen hypervisor API
> where you pass in a reference to pte entry for the hypervisor to put
> mappings into, and the rest of the pagetable needs to exist. The Xen
> code uses the side-effect of apply_to_page_range() to create pagetable
> for these calls.

I think adding a flags field and an allocate flag to my callback
struct would be sufficient here.

> > I'd gotten the impression that these sorts of typedefs were out of
> > fashion.
> >
>
> In general yes, but for function pointers the syntax is so clumsy that I
> think typedefs are OK.

The syntax is horrible, but I don't think we end up using the
resultant type enough to justify the namespace pollution.

--
Mathematics is the supreme nostalgia of our time.
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2007-04-17 23:13    [W:0.189 / U:0.192 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site