Messages in this thread | | | Date | Tue, 27 Feb 2007 16:49:53 -0800 | From | Jeremy Fitzhardinge <> | Subject | Re: [patch 06/26] Xen-paravirt_ops: paravirt_ops: allocate a fixmap slot |
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Jeremy Fitzhardinge wrote: > Ingo Molnar wrote: > >> why not vmalloc it on the guest side? fixmaps are bad for this purpose >> for a general paravirt implementation, it limits the size of the shared >> info page, etc. >> > > Yes. vmalloc would have the annoying side-effect of actually allocating > some pages which would be shadowed by the remapping, but I guess > get_vm_area would do the job. I'll give it a go.
Hm, this is a bit awkward. We need to map the shared info page fairly early - say, around paging_init - but we're still on the bootmem allocator at that point, so get_vm_area isn't usable yet. Using a fixmap keeps things simple. It seems to me that having a single fixmap available is useful for this kind of simple/early mapping, and if someone needs to map something larger, then they can put it off until get_vm_area() is available...
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