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.
