On 2018-12-18 10:26, Janosch Frank wrote: > LPAR and z/VM start in esam mode depending on the hardware, so we need > to switch to z/Arch and set 64 bit addressing. > > Under Qemu/KVM we already start out with both when being run with the > Qemu --kernel argument or we lack 64 bit when booting from disk > because of the initial psw specifying 31 bit for z/VM and lpar > compatibility. > > Signed-off-by: Janosch Frank <frankja@xxxxxxxxxxxxx> > Reviewed-by: David Hildenbrand <david@xxxxxxxxxx> > --- > s390x/cstart64.S | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/s390x/cstart64.S b/s390x/cstart64.S > index d382497..7886f35 100644 > --- a/s390x/cstart64.S > +++ b/s390x/cstart64.S > @@ -20,9 +20,17 @@ > * > * For KVM and TCG kernel boot we are in 64 bit z/Arch mode. > * When booting from disk the initial short psw is in 31 bit mode. > + * When running under LPAR or z/VM, we might start in 31 bit and esam mode. > */ > .globl start > start: > + /* Switch to z/Architecture mode and 64-bit */ > + slr %r0, %r0 # Set cpuid to zero > + lhi %r1, 2 # mode 2 = esame > + sigp %r1, %r0, 0x12 # sigp set arch > + bras %r13,0f # Jump over zero area > + .fill 16,4,0x0 # Zero area for lmh > +0: lmh %r0,%r15,0(%r13) # Clear high-order half of gprs Do we really want to keep the lmh here? ... yes, I know the kernel is doing this, too, but I really fail to see why we would need it in the kvm-unit-tests, too... have you tried it also without this clearing? Thomas
