Comment 0 for bug 1542941

Commit 633d6f17cd91ad5bf2370265946f716e42d388c6 (aka 38d30afb12140c0e3a446fe779dc9cd29548f313 in vivid) in Xen domU causes high resource requirements in the underlying target dom0 (migrating a 64-bit domU involves a 1GB malloc in dom0, as well as a lot of unnecessary work).

In my specific case, that 1GB malloc fails as my dom0s aren't big enough, causing all migrations to fail with the migrating VM suspended.

This is fixed in commit 98dd166ea3a3c3b57919e20d9b0d1237fcd0349d "x86/xen: prepare p2m list for memory hotplug":

"""
Commit 054954eb051f35e74b75a566a96fe756015352c8 ("xen: switch to linear
virtual mapped sparse p2m list") introduced a regression regarding to
memory hotplug for a pv-domain: as the virtual space for the p2m list
is allocated for the to be expected memory size of the domain only,
hotplugged memory above that size will not be usable by the domain.

Correct this by using a configurable size for the p2m list in case of
memory hotplug enabled (default supported memory size is 512 GB for
64 bit domains and 4 GB for 32 bit domains).

Signed-off-by: Juergen Gross <email address hidden>
Cc: <email address hidden> # 3.19+
Reviewed-by: Daniel Kiper <email address hidden>
Signed-off-by: David Vrabel <email address hidden>
"""

Please consider incorporating 98dd166ea3a3c3b57919e20d9b0d1237fcd0349d into the wily and vivid kernels. Thanks.