Milton Miller wrote: > I wrote: > >> On Mon Jul 19 2010 at about 03:36:51 EST, Alexander Graf wrote: >> >>> On 19.07.2010, at 03:11, Benjamin Herrenschmidt wrote: >>> >>> >>>> On Thu, 2010-07-15 at 17:05 +0530, Subrata Modak wrote: >>>> >>>>> commit e62cee42e66dcca83aae02748535f62e0f564a0c solved the problem for >>>>> 2.6.34-rc6. However some other bad relocation warnings generated against >>>>> 2.6.35-rc5 on Power7/ppc64 below: >>>>> >>>>> MODPOST 2004 modules^M >>>>> WARNING: 2 bad relocations^M >>>>> c000000000008590 R_PPC64_ADDR32 .text+0x4000000000008460^M >>>>> c000000000008594 R_PPC64_ADDR32 .text+0x4000000000008598^M >>>>> >>>> I think this is KVM + CONFIG_RELOCATABLE. Caused by: >>>> >>>> .global kvmppc_trampoline_lowmem >>>> kvmppc_trampoline_lowmem: >>>> .long kvmppc_handler_lowmem_trampoline - CONFIG_KERNEL_START >>>> >>>> .global kvmppc_trampoline_enter >>>> kvmppc_trampoline_enter: >>>> .long kvmppc_handler_trampoline_enter - CONFIG_KERNEL_START >>>> >>>> Alex, can you turn these into 64-bit on ppc64 so the relocator >>>> can grok them ? >>>> >>> If I turn them into 64-bit, will the values be > RMA? In that case >>> things would break anyways. How does relocation work on PPC? Are the >>> first few megs copied over to low memory? Would I have to mask anything >>> in the above code to make sure I use the real values? >>> >>> Alex >>> >>> >> You can still do the subtraction, but you have to allocate 64 bits for >> storage. Relocatable ppc64 kernels work by adjusting PPC64_RELOC_RELATIVE >> entries during early boot (reloc in reloc_64.S called from head_64.S). >> >> The code purposely only supports 64 bit relative addressing. >> > > Oh yea, and for book-3s, the code copies from 0x100 to __end_interrupts > in arch/powerpc/kernel/exceptions-64s.h down to the real 0, but the rest > of the kernel is at some disjointed address. The interrupt will go to > the copy at the real zero. Any references to code outside that region > must be done via a full indrect branch (not a relative one), simiar to > the secondary startup (via following the function pointer in a descriptor > set in very low memory), or syscall entry and exception vectors via paca. >
That would still break on normal PPC boxes, as any address accessed in real mode has to be inside the RMA. And the #include for kvm/book3s_rmhandlers.S happens after __end_interrupts. So I'd end up with code that gets executed outside of the RMA after a relocation, right? Alex _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
