Re: [kvm-unit-tests PATCH v2 4/7] lib/alloc_page: complete rewrite of the page allocator

[Claudio Imbrenda <imbrenda@linux.ibm.com>]

On Tue, 8 Dec 2020 15:26:10 +0100
Andrew Jones <drjones@redhat.com> wrote:

[...]
 
> > > are not apparent when the memory is zeroed. I do not think anyone
> > > wants to waste time on resolving these bugs.  
> > 
> > I disagree. if a unit test has a bug, it should be fixed.
> > 
> > some tests apparently need the allocator to clear the memory, while
> > other tests depend on the memory being untouched. this is clearly
> > impossible to solve without some kind of switch
> > 
> > 
> > I would like to know what the others think about this issue too
> >  
> 
> If the allocator supports memory being returned and then reallocated,
> then the generic allocation API cannot guarantee that the memory is
> untouched anyway. So, if a test requires untouched memory, it should
> use a specific API. I think setup() should probably just set some
> physical memory regions aside for that purpose, exposing them somehow
> to unit tests. The unit tests can then do anything they want with
> them. The generic API might as well continue zeroing memory by
> default.

I think I have an idea for a solution that will allow for untouched
pages and zeroed pages, on request, without any additional changes.

Give me a few days ;)

> I never got around to finishing my review of the memory areas. Maybe
> that can be modified to support this "untouched" area simply by
> labeling an area as such and by not accepting returned pages to that
> area.
> 
> Thanks,
> drew
>