[Xen-devel] Re: [patch 05/21] Xen-paravirt: paravirt_ops: allocate a fixmap slot

[Gerd Hoffmann <kraxel@xxxxxxx>]

Dan Hecht wrote:
> Right.  But that is only because Xen decides to allocate the page from 
> the (machine) physical space, rather than from the pseudo-physical 
> space.  My question is: why doesn't Xen allocate shared_info from the 
> pseudo-physical space?

Historical reasons ...

> If it had, then this page wouldn't need to be 
> treated specially.  I'm not sure, but I seem to remember on 64-bit 
> Xen/XenLinux allocated shared_info from pseudo-physical space already...

Yep, the ia64 port which came later handles some things differently,
specifically some "magic" pages are allocated more clever ;)

Changing that for x86 would break existing guests though.

cheers,
  Gerd

-- 
Gerd Hoffmann <kraxel@xxxxxxx>

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