On Wed, Feb 14, 2007 at 08:37:26AM +0000, Jan Beulich wrote:

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Jeremy Fitzhardinge [off-list ref] 14.02.07 02:36 >>>

Dan Hecht wrote:

quoted

Why doesn't Xen allocate the shared_info page from the pseudo-physical
space?  Doesn't it already have to steal pages from the
pseudo-physical space for e.g. initial page tables, console, etc?  Why
not do the same for shared_info, and then you don't need a reserve the
fixmap slot.

Unlike the pagetable pages or the console page, the shared info page
doesn't have a pseudo-physical address, so in order to map it we need to
directly construct a pte containing the mfn for that page.  Inserting
this mapping into the fixmap space seems like the easiest way to do
this.  It's not like a fixmap slot costs anything.

Otoh there are many fixmap slots not used under Xen, perhaps it would
be possible to use one of those... One slot certainly doesn't cost a lot,

I don't have a problem with reserving one page for this.

-Andi