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H A D | configure | e9a3591fa09f273592451f8b9f83692bcbedb60c Wed Aug 23 05:16:23 CDT 2017 Christian Borntraeger <borntraeger@de.ibm.com> configure: enable --s390-pgste linker option
KVM guests on s390 need a different page table layout than normal processes (2kb page table + 2kb page status extensions vs 2kb page table only). As of today this has to be enabled via the vm.allocate_pgste sysctl.
Newer kernels (>= 4.12) on s390 check for an S390_PGSTE program header and enable the pgste page table extensions in that case. This makes the vm.allocate_pgste sysctl unnecessary. We enable this program header for the s390 system emulation (qemu-system-s390x) if we build on s390 - for s390 system emulation - the linker supports --s390-pgste (binutils >= 2.29) - KVM is enabled
This will allow distributions to disable the global vm.allocate_pgste sysctl, which will improve the page table allocation for non KVM processes as only 2kb chunks are necessary.
Cc: Christian Ehrhardt <christian.ehrhardt@canonical.com> Cc: Alexander Graf <agraf@suse.de> Cc: Dan Horak <dhorak@redhat.com> Cc: David Hildenbrand <david@redhat.com> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com> Acked-by: Janosch Frank <frankja@linux.vnet.ibm.com> Reviewed-by: Thomas Huth <thuth@redhat.com> Message-Id: <1503483383-199649-1-git-send-email-borntraeger@de.ibm.com> Reviewed-by: David Hildenbrand <david@redhat.com> Signed-off-by: Cornelia Huck <cohuck@redhat.com>
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