RE: [PATCH v4 05/10] xen/domain: Add DOMCTL handler for claiming memory with NUMA awareness

[Bernhard Kaindl <bernhard.kaindl@xxxxxxxxxx>]

Hello Jan,

I only reply here to acknowledge your comment. This code is obsolete now:

It is historical with v6 now, where we have new code and different 
considerations
that would be off topic for this discussion on the obsolete v4 series (the 
single-
node interface doesn't exist in v6, the new implementation is multi-node)

> >> +    if ( claim.node == XEN_DOMCTL_CLAIM_MEMORY_NO_NODE )
> >>> +        claim.node = NUMA_NO_NODE;
> >>
> >> What about the incoming claim.node being NUMA_NO_NODE? Imo the range 
> >> checking
> >> the previous patch adds to domain_set_outstanding_pages() wants to move 
> >> here,
> >> at which point the function's new parameter could be properly nodeid_t.
> >
> > nodeid_t and NUMA_NO_NODE have (judging by the existing implementation) are 
> > not
> > exposed in the public API to the control domain.
> >
> > This separation is probably a good thing because it allows to change Xen 
> > internals
> > like nodeit_t and NUMA_NO_NODE if so desired without changing the public 
> > API.
> >
> > NUMA_NO_NODE is defined as 0xFF and nodeid_t is u8. But that is just an
> > implementation detail of the Hypervisor itself. If needed, we could change
> > the implementation like this series could do, if wanted.
> 
> You spell it all out here, but then you don't draw the conclusion that I was 
> aiming
> at: If someone passes in 0xff, that _should not_ be mistaken for 
> NUMA_NO_NODE. Hence
> for the time being you simply need to reject 0xff if you don't want to expose 
> "no
> specific node" exactly that way in the ABI. And indeed ...

Ah, I misunderstood your comment, acknowledged.

Earlier reviews asked for node checking in domain_set_outstanding_pages(), which
should, as you suggested have been moved there. But that's historical with v6 
now,
where we have new code and different considerations.

    cu, Bernhard

PS: I submitted the current design document to reason the design, and v6 itself:
https://bernhard-xen.readthedocs.io/en/claim-sets-v2-design/designs/claims
https://lists.xenproject.org/archives/html/xen-devel/2026-04/msg00587.html