On Wed, Jan 09, 2002 at 12:08:47AM -0700, Jason Gunthorpe wrote: > I just noticed that in setup.c there is this little bit: > > s = read_32bit_cp0_register(CP0_STATUS); > s &= ~(ST0_CU1|ST0_CU2|ST0_CU3|ST0_KX|ST0_SX|ST0_FR); > s |= ST0_CU0; > write_32bit_cp0_register(CP0_STATUS, s); > > And it doesn't mask off ST0_UX - is this an oversight? With my RM7K the > kernel is called with ST0_UX set, and since it doesn't clear it the XTLB > handler is called - which faults things.. On all firmware I've made the 32-bit kernel run on it is invoked with UX cleared so I just didn't bother to clear it myself. > So, would this patch be appropriate in general: > > --- setup.c 2001/12/02 11:34:38 1.96 > +++ setup.c 2002/01/09 08:05:43 > @@ -558,7 +558,7 @@ > > /* Disable coprocessors and set FPU for 16 FPRs */ > s = read_32bit_cp0_register(CP0_STATUS); > - s &= ~(ST0_CU1|ST0_CU2|ST0_CU3|ST0_KX|ST0_SX|ST0_FR); > + s &= ~(ST0_CU1|ST0_CU2|ST0_CU3|ST0_UX|ST0_KX|ST0_SX|ST0_FR); > s |= ST0_CU0; > write_32bit_cp0_register(CP0_STATUS, s); > > or is it better to make the xtlb handler work in the 32 bit case? No, your patch is the right thing. Enabeling UX would also permit the use of 64-bit instructions and that wouldn't work on the 32-bit kernel. Ralf
