On 08/23/2017 02:31 PM, Cornelia Huck wrote: > On Wed, 23 Aug 2017 12:16:23 +0200 > Christian Borntraeger <borntrae...@de.ibm.com> wrote: > >> 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.ehrha...@canonical.com> >> Cc: Alexander Graf <ag...@suse.de> >> Cc: Dan Horak <dho...@redhat.com> >> Cc: David Hildenbrand <da...@redhat.com> >> Signed-off-by: Christian Borntraeger <borntrae...@de.ibm.com> >> Acked-by: Janosch Frank <fran...@linux.vnet.ibm.com> >> --- >> V1->V2: >> - provide ld_has function >> - use ld_has to replace some open coded variants >> - check target arch and arch for s390 >> - check for s390x before calling the linker >> V2->V3: >> - fix typos >> configure | 21 ++++++++++++++++++++- >> 1 file changed, 20 insertions(+), 1 deletion(-) > > Looks sane. > > I guess I'll wait for some more Acks or R-bs and then queue it to > s390-next.
Sure. Looks like I forgot to add Thomas/Davids R-bs, so please add those.
