All the code in OpenBIOS runs in 32 bits, which is fine. Now, when an interrupt arrives, the 970 CPU automatically sets the MSR_SF bit, making us run in 64 bit mode.
That breaks address calculation, because 'lis' and 'ba' get sign extended.
In order to circumvent that mess, let's just go back to 32 bit mode whenever we get an interrupt.
Signed-off-by: Alexander Graf alex@csgraf.de --- arch/ppc/qemu/start.S | 3 +++ 1 files changed, 3 insertions(+), 0 deletions(-)
diff --git a/arch/ppc/qemu/start.S b/arch/ppc/qemu/start.S index 857885a..66df9a2 100644 --- a/arch/ppc/qemu/start.S +++ b/arch/ppc/qemu/start.S @@ -34,6 +34,9 @@
#define EXCEPTION_PREAMBLE_TEMPLATE \ mtsprg1 r1 ; /* scratch */ \ + mfmsr r1 ; /* unset MSR_SF */ \ + clrlwi r1,r1,0 ; \ + mtmsr r1 ; \ mfsprg0 r1 ; /* exception stack in sprg0 */ \ .ifc ULONG_SIZE, 8 ; \ addi r1,r1,-(40 * ULONG_SIZE) ; /* push exception frame */ \