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[Xen-devel] Re: xen: memory initialization/balloon fixes (#3)

On Thu, Sep 15, 2011 at 01:29:21PM +0100, David Vrabel wrote:
> This set of patches fixes some bugs in the memory initialization under
> Xen and in Xen's memory balloon driver.  They can make 100s of MB of
> additional RAM available (depending on the system/configuration).
> Patch 1 is already applied.
> Patch 2 fixes a bug in patch 1 and should be queued for 3.1 (and along
> with patch 1 considered for 3.0 stable).
> Patch 3 is a bug fix and should be queued for 3.1 and possibly
> queued for the 3.0 stable tree.
> Patches 5 & 6 increase the amount of low memory in 32 bit domains
> started with < 1 GiB of RAM.  Please queue for 3.2

I've queued them up and going to test them this week to make sure
there are no regressions.

> Patch 7 releases all pages in the initial allocation with PFNs that
> lie within a 1-1 mapping.  This seems correct to me as I think that

The only thing I remember about this was with dmidecode doing something
fishy.. (As in, it wouldn't work when the pages under 1MB were released)
(But I can't remember the details about it, so I might be completly

Could you please test that as well?

> once the 1-1 mapping is set the MFN of the original page is lost so
> it's no longer accessible by the kernel (and it cannot be used by
> another domain
> Changes since #2:
> - New patch: xen: avoid adding non-existant memory if the reservation
>   is unlimited
> - Avoid using a hypercall to get the current number of pages in the
>   ballon driver.  Apparently the hypercall won't return the right
>   value if paging is used.
> - Addresses Konrad's review comments.
> David

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