The typical kernel + user space I boot on the prep machine no longer boots due to an issue accessing the PVR special purpose register. When the PVR is accessed from user space, it should generate an exception with the PC set to the instruction that it occurred at when it saves to the stack. In the latest CVS, it is off by 4 bytes. With out the fix /sbin/init gets killed because the kernel's trap handler which does the userspace emulation of the instruction does not clean up the trap.
I am using the attached patch to work around the problem, but I wonder if there is a more generic problem that was introduced as a regression with all ppc merges in the last month or so, given this used to work fine through the generic handler. Any insight into this would certainly be useful. Thanks, Jason.
Work around the problem that the PC register is not saved with the right address when taking a user space PVR access exception. Signed-off-by: Jason Wessel <[EMAIL PROTECTED]> --- target-ppc/translate_init.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) --- a/target-ppc/translate_init.c +++ b/target-ppc/translate_init.c @@ -92,6 +92,13 @@ static void spr_write_clear (void *opaqu } #endif +static void spr_read_generic_fault_user(void *opaque, int sprn) +{ + DisasContext *ctx = opaque; + ctx->nip -= 4; + GEN_EXCP_PRIVREG(ctx); +} + /* SPR common to all PowerPC */ /* XER */ static void spr_read_xer (void *opaque, int sprn) @@ -5942,7 +5949,7 @@ static void init_ppc_proc (CPUPPCState * /* Register SPR common to all PowerPC implementations */ gen_spr_generic(env); spr_register(env, SPR_PVR, "PVR", - SPR_NOACCESS, SPR_NOACCESS, + &spr_read_generic_fault_user, SPR_NOACCESS, &spr_read_generic, SPR_NOACCESS, def->pvr); /* PowerPC implementation specific initialisations (SPRs, timers, ...) */