* alpha-osf1-tdep.c (alpha_osf1_init_abi): Unfortunately,

        procfs appears to be broken when debugging on multi-processor
        machines. So enable software single stepping in order to avoid
        using the procfs interface to do next/step operations, using
        internal breakpoints instead.

        * infrun.c (handle_inferior_event): Readjust the stop_pc by
        DECR_PC_AFTER_BREAK when hitting a single step breakpoint, to
        make this pc address equal to the value it would have if the
        system stepping capability was used. Also set a new flag used
        to ensure that we don't readjust the PC one more time later.

        * breakpoint.c (bpstat_stop_status): Do not adjust the PC
        address by DECR_PC_AFTER_BREAK when software single step is
        in use for this architecture, as this has already been taken
        care of in handle_inferior_event().

1 files changed, 4 insertions, 0 deletions

diff --git a/gdb/alpha-osf1-tdep.c b/gdb/alpha-osf1-tdep.c
index 12320519ae8..ece5e2694f2 100644
--- a/gdb/alpha-osf1-tdep.c
+++ b/gdb/alpha-osf1-tdep.c
@@ -58,6 +58,10 @@ alpha_osf1_init_abi (struct gdbarch_info info,
   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 
   set_gdbarch_pc_in_sigtramp (gdbarch, alpha_osf1_pc_in_sigtramp);
+  /* The next/step support via procfs on OSF1 is broken when running
+     on multi-processor machines. We need to use software single stepping
+     instead.  */
+  set_gdbarch_software_single_step (gdbarch, alpha_software_single_step);
 
   tdep->skip_sigtramp_frame = alpha_osf1_skip_sigtramp_frame;
   tdep->sigcontext_addr = alpha_osf1_sigcontext_addr;