Messages in this thread | | | Date | Wed, 02 Apr 2008 14:35:42 -0700 | From | Jeremy Fitzhardinge <> | Subject | Re: [PATCH RFC] hotplug-memory: refactor online_pages to separate zone growth from page onlining |
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Dave Hansen wrote: > Oh, once we've let Linux establish ptes to it, we've required that the > hypervisor have it around? How does that work with the balloon driver? > Do we destroy the ptes when giving balloon memory back to the > hypervisor? >
Yep. It removes any mapping before handing it back to the hypervisor.
> If we're talking about i386, then we're set. We don't map the hot-added > memory at all because we only add highmem on i386. The only time we map > these pages is *after* we actually allocate them when they get mapped > into userspace or used as vmalloc() or they're kmap()'d. >
Well, the balloon driver can balloon out lowmem pages, so we have to deal with mappings either way. But balloon+hotplug would work identically on x86-64, so all pages are mapped.
>> I think we're getting off track here; this is a lot of extra complexity >> to justify allowing usermode to use /sys to online a chunk of hotplugged >> memory. >> > > Either that, or we're going to develop the entire Xen/kvm memory hotplug > architecture around the soon-to-be-legacy i386 limitations. :)
Everything also applies to x86-64.
J
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