[Xen-devel] Re: Will map_domain_page return NULL when fails on x86_32?

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>]

On 27 Feb 2006, at 13:34, Li, Xin B wrote:

> > > Hi Keir, just a curious question, will map_domain_page
> > return NULL when
> > > fails on x86_32? If not, why?
> > > thanks
> > I don't expect that it should ever fail. It's used for temporary
> > mappings (e.g., scope of a function) and so even though the mapping
> > space is finite, we shouldn't ever exhaust it.
> So the unmap is not a must?
> Can you explain the mechanism of garbage collection here?
> Thanks
The unmap is a must. After unmap the mapping is put in a per-vcpu 
lookup table to allow fast reuse. When it is evicted from that table 
then it is freed.
 -- Keir


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