Re: [Xen-devel] Re: [patch 12/21] Xen-paravirt: Allocate and freevmalloc areas

From: Keir Fraser
Date: Fri Feb 16 2007 - 18:31:27 EST

On 16/2/07 19:26, "Jeremy Fitzhardinge" <jeremy@xxxxxxxx> wrote:

> Keir Fraser wrote:
>> Hmmm... Actually looks like a bunch of architectures do lazy sync of the
>> vmalloc area, although neither ia64 nor powerpc does so. However, all
>> current users of the alloc_vm_area() function would be okay since none of
>> the other lazy-syncing architectures are supported by Xen.
> Well, assuming that alloc_vm_area() has some non-Xen use, the right
> thing is for archs to export vmalloc_sync_all(), and just use that from
> common code.

It has no other users right now and get_vm_area_sync() would be a
better-named and more generically useful function than alloc_vm_area(). But
yes, to be done properly it does require vmalloc_sync_all() to be defined by
all architectures (even if that's BUG() and implement-properly-on-demand).

get_vm_area_sync(), partnered with existing remove_vm_area(), just seems
much smaller and neater than adding four new functions with a more complex
usage: alloc_vm_area, {lock,unlock}_vm_area, and free_vm_area. Maybe keeping
free_vm_area() too makes sense as its interface is more neatly symmetrical
to that of get_vm_area().

-- Keir

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