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 | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/s390x/cstart64.S b/s390x/cstart64.S index d382497..6622633 100644 --- a/s390x/cstart64.S +++ b/s390x/cstart64.S @@ -11,6 +11,7 @@ * under the terms of the GNU Library General Public License version 2. */ #include <asm/asm-offsets.h> +#include <asm/sigp.h> .section .init @@ -20,9 +21,18 @@ * * 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, SIGP_SET_ARCHITECTURE + /* XOR all registers with themselves to clear them fully. */ + .irp i, 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15 + xgr \i,\i + .endr sam64 # Set addressing mode to 64 bit /* setup stack */ larl %r15, stackptr -- 2.14.3
