[PATCH] Page scrubbing

[PATCH] Page scrubbing

[Christoph Egger]

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Hi!

Make scrub_heap_pages() print from where to where
it scrubs pages.

Signed-off-by: Christoph Egger <Christoph.Egger@amd.com>


This patch uncovers a strange behaviour on 32bit.
On 64bit I get this:

(XEN) Scrubbing Free RAM 0xffff830000100000 -> 0xffff83003fff0000: ....done.

On 32bit I get this:

(XEN) Scrubbing Free RAM 0xffc00000 -> 
0xdefb0000: .............................done.

On 64bit the scrubber goes up, but on 32bit it goes down.
Is this behaviour expected?


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Operating System Research Center

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diff -r 9071521d4864 xen/common/page_alloc.c
--- a/xen/common/page_alloc.c	Fri Sep 07 11:39:10 2007 +0100
+++ b/xen/common/page_alloc.c	Thu Aug 16 17:00:26 2007 +0200
@@ -596,7 +596,9 @@ void __init scrub_heap_pages(void)
     if ( !opt_bootscrub )
         return;
 
-    printk("Scrubbing Free RAM: ");
+    printk("Scrubbing Free RAM 0x%p -> 0x%p: ",
+        page_to_virt(mfn_to_page(first_valid_mfn)),
+        page_to_virt(mfn_to_page(max_page)));
 
     for ( mfn = first_valid_mfn; mfn < max_page; mfn++ )
     {

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Re: [PATCH] Page scrubbing

[Keir Fraser]

The printk() is printing nonsense for x86/32, as most pages do not have a
permanent mapping in Xen, and hence no valid virtual address. Page_to_virt()
on such pages is not allowed.

 -- Keir

On 11/9/07 16:07, "Christoph Egger" <Christoph.Egger@amd.com> wrote:

> 
> Hi!
> 
> Make scrub_heap_pages() print from where to where
> it scrubs pages.
> 
> Signed-off-by: Christoph Egger <Christoph.Egger@amd.com>
> 
> 
> This patch uncovers a strange behaviour on 32bit.
> On 64bit I get this:
> 
> (XEN) Scrubbing Free RAM 0xffff830000100000 -> 0xffff83003fff0000: ....done.
> 
> On 32bit I get this:
> 
> (XEN) Scrubbing Free RAM 0xffc00000 ->
> 0xdefb0000: .............................done.
> 
> On 64bit the scrubber goes up, but on 32bit it goes down.
> Is this behaviour expected?
>