Re: [Xen-devel] [PATCH v4 08/16] xen/mm: Drop the parameter mfn from populate_pt_range

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Wed, Feb 21, 2018 at 02:02:51PM +0000, Julien Grall wrote:
> The function populate_pt_range is used to populate in advance the
> page-table but it will not do the actual mapping. So passing the MFN in
> parameter is pointless. Note that the only caller pass 0...
> 
> At the same time replace 0 by INVALID_MFN to make clear the MFN is
> invalid.
> 

The mfn parameter is the first mfn of a consecutive nr MFNs passed to
map_pages_to_xen. Putting INVALID_MFN isn't helping -- the value written
to page table(s) will wrap around to 0.

And I think starting from 0 to avoid overflow is probably a better
behaviour. If you really want to make sure all entries are filled with
INVALID_MFN you should call map_pages_to_xen for nr times with each
page.

Wei.

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxxx
https://lists.xenproject.org/mailman/listinfo/xen-devel