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| author | Juergen Gross <jgross@suse.com> | 2015-07-17 06:51:36 +0200 |
|---|---|---|
| committer | David Vrabel <david.vrabel@citrix.com> | 2015-08-20 12:24:24 +0100 |
| commit | c70727a5bc18a5a233fddc6056d1de9144d7a293 (patch) | |
| tree | 98c09e90e78f0d3bb79be2592e3bed5e5c847f83 /Documentation/kernel-parameters.txt | |
| parent | 70e61199559a09c62714694cd5ac3c3640c41552 (diff) | |
| download | lwn-c70727a5bc18a5a233fddc6056d1de9144d7a293.tar.gz lwn-c70727a5bc18a5a233fddc6056d1de9144d7a293.zip | |
xen: allow more than 512 GB of RAM for 64 bit pv-domains
64 bit pv-domains under Xen are limited to 512 GB of RAM today. The
main reason has been the 3 level p2m tree, which was replaced by the
virtual mapped linear p2m list. Parallel to the p2m list which is
being used by the kernel itself there is a 3 level mfn tree for usage
by the Xen tools and eventually for crash dump analysis. For this tree
the linear p2m list can serve as a replacement, too. As the kernel
can't know whether the tools are capable of dealing with the p2m list
instead of the mfn tree, the limit of 512 GB can't be dropped in all
cases.
This patch replaces the hard limit by a kernel parameter which tells
the kernel to obey the 512 GB limit or not. The default is selected by
a configuration parameter which specifies whether the 512 GB limit
should be active per default for domUs (domain save/restore/migration
and crash dump analysis are affected).
Memory above the domain limit is returned to the hypervisor instead of
being identity mapped, which was wrong anyway.
The kernel configuration parameter to specify the maximum size of a
domain can be deleted, as it is not relevant any more.
Signed-off-by: Juergen Gross <jgross@suse.com>
Acked-by: Konrad Rzeszutek Wilk <Konrad.wilk@oracle.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Diffstat (limited to 'Documentation/kernel-parameters.txt')
| -rw-r--r-- | Documentation/kernel-parameters.txt | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 1d6f0459cd7b..47f7b985f833 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -4078,6 +4078,13 @@ bytes respectively. Such letter suffixes can also be entirely omitted. plus one apbt timer for broadcast timer. x86_intel_mid_timer=apbt_only | lapic_and_apbt + xen_512gb_limit [KNL,X86-64,XEN] + Restricts the kernel running paravirtualized under Xen + to use only up to 512 GB of RAM. The reason to do so is + crash analysis tools and Xen tools for doing domain + save/restore/migration must be enabled to handle larger + domains. + xen_emul_unplug= [HW,X86,XEN] Unplug Xen emulated devices Format: [unplug0,][unplug1] |