Re: [XEN PATCH v3 3/3] xen/mm: add declaration for first_valid_mfn

[Nicola Vetrini <nicola.vetrini@xxxxxxxxxxx>]

Hi Jan, Julien

> > > +extern mfn_t first_valid_mfn;
> > > +
> > >    /*
> > >     * Create only non-leaf page table entries for the
> > >     * page range in Xen virtual address space.
> > ... I still disagree with the placement here (should be xen/numa.h 
> > imo),
> I don't care too much about which header is used. So I am ok with 
> numa.h if this is what you really want. However...
> > and I still don't see why we can't carry out the TODO right away, if 
> > we
> > have to touch all of this anyway. If it's really too much to ask from
> > the original contributor, I can certainly see about making a patch 
> > myself
> There are a few reasons I didn't update with that approach or want to 
> ask Nicola for this:
>   1. I assume this will be a macro and it is not clear to me whether 
> Eclair would be able to detect the visibility change based on the 
> config
>   2. IMHO, this is obfuscating a bit more the code
>   3. I don't see why we want to special case first_valid_mfn. I am sure 
> we have other external variables in the same situation.
> So if any solution needs to came up, then it needs to be generic, and I 
> fear this is going to be yet another lengthy work which is not worth it 
> for this case.
> > (and I've now added this to my short-term TODO list).
> Thanks. But as I wrote above, I am not sure I agree such proposal. Let 
> see what the code looks like.
Given the controversy that arose on this patch, maybe it's best to drop 
it now from this series. If then it's agreed that as a temporary 
workaround you want to leave it as is and deviate, as I proposed 
elsewhere in the thread, feel free to reach out. Meanwhile, if patch 1 
looks ok I can mark this series as done and focus on the v2 for R2.1, 
which is almost ready.
--
Nicola Vetrini, BSc
Software Engineer, BUGSENG srl (https://bugseng.com)