Re: [Qemu-devel] [RFC PATCH v5 6/6] spapr: Don't allow memory hotplug to memory less nodes

[David Gibson]

On Thu, Jun 25, 2015 at 11:44:15AM +0530, Bharata B Rao wrote:
> Currently PowerPC kernel doesn't allow hot-adding memory to memory-less
> node, but instead will silently add the memory to the first node that has
> some memory. This causes two unexpected behaviours for the user.
> 
> Memory gets hotplugged to a different node than what the user specified.
> Since pc-dimm subsystem in QEMU still thinks that memory belongs to
> memory-less node, a reboot will set things accordingly and the previously
> hotplugged memory now ends in the right node. This appears as if some
> memory moved from one node to another.
> 
> So until kernel starts supporting memory hotplug to memory-less
> nodes, just prevent such attempts upfront in QEMU.
> 
> Signed-off-by: Bharata B Rao <address@hidden>

I presume you're talking about host kernel limitations here?

If that does get changed in future we'll need some sort of ugly compat
test in qemu to see if the new kernel can handle it, but there's no
way to avoid that, so.

Reviewed-by: David Gibson <address@hidden>

-- 
David Gibson                    | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au  | minimalist, thank you.  NOT _the_ _other_
                                | _way_ _around_!
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