RE: [Xen-devel] Review needed for "commonisation" ofcommon/grant_table.c

["Tian, Kevin" <kevin.tian@xxxxxxxxx>]

>-----Original Message-----
>From: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
>[mailto:xen-devel-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of
Magenheimer,
>Dan (HP Labs Fort Collins)
>Sent: Saturday, June 11, 2005 5:57 AM
>To: cwc22@xxxxxxxxx
>
>> What do these comments mean? -:
>> // FIXME-ia64: any error checking need to be done here?
>
>It means that on x86, there are a number of error conditions due
>to the way page tables are handled, but none (or perhaps different
>error conditions) apply on ia64.  The checks for the page table
>issues are x86 specific and would need to be macro-ized somehow
>for the code to be portable.

Yes. So can I suggest splitting grant table into common part and
arch-dep part? Though not looking into detail code of grant table yet,
there should be many places operating on page table which should be.
That would be better than adding arch definition in common part. :)
Other page table related stuff has already been pulled into
arch-dependent directories (majorly meaning mm.c).

>
>> Why doesn't ia64 use put_page and put_page_type? Isn't there a frame
>> table with reference counts on ia64?
>
>There's a frame table but no reference counts because there
>are no "special" (e.g. L1 page table) frames (at least not
>in the current implementation).  No get_page either (but that
>is only used in code which is commented out for other x86-specific
>reasons).
>

We need reference counts on ia64, not for special page, but page share.
Front end driver and VBD needs to share pages that domA owns to domB
where backend is running. Also shared info frame will be shared between
domain and xen, where reference count is also necessary. We'll send a
patch to you after grabbing it from our local tree cleanly. :)

Thanks,
Kevin

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