Messages in this thread | | | From | Juergen Gross <> | Subject | [PATCH V3] xen: remove some memory limits from pv-domains | Date | Wed, 17 Sep 2014 16:59:40 +0200 |
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When a Xen pv-domain is booted the initial memory map contains multiple objects in the top 2 GB including the initrd and the p2m list. This limits the supported maximum size of the initrd and the maximum memory size the p2m list can span is limited to about 500 GB.
Xen however supports loading the initrd without mapping it and the initial p2m list can be mapped by Xen to an arbitrary selected virtual address. The following patches activate those options and thus remove the limitations.
It should be noted that the p2m list limitation isn't only affecting the amount of memory a pv domain can use, but it also hinders Dom0 to be started on physical systems with larger memory without reducing it's memory via a Xen boot parameter. By mapping the initial p2m list to an area not in the top 2 GB it is now possible to boot Dom0 on such systems.
It would be desirable to be able to use more than 512 GB in a pv domain, but this would require a reorganization of the p2m tree built by the kernel at boot time. As this reorganization would affect the Xen tools and kexec, too, it is not included in this patch set. This topic can be addressed later.
Changes since V2: - 2 patches dropped, as they are already applied - added helper function and updated comment and patch description as requested by David Vrabel
Juergen Gross (1): xen: eliminate scalability issues from initial mapping setup
arch/x86/xen/mmu.c | 119 +++++++++++++++++++++++++++++++++++++++++++++--- arch/x86/xen/setup.c | 65 ++++++++++++++------------ arch/x86/xen/xen-head.S | 2 + 3 files changed, 151 insertions(+), 35 deletions(-)
-- 1.8.4.5
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