Re: [Qemu-devel] [PATCH] qemu will core dump with "-smp 254, , sockets=2, cores=3, threads=2"

[lijun <junmuzi@gmail.com>]

As Eric and Eduardo's suggestions, use is_power_of_2 to check whether 
nr_cores
and nr_threads is the power of 2 in function x86_apicid_from_cpu_idx in file
target-i386/topology.h. This check is very simple, I prefer add it in a
function to write a new function. Thanks for Eric and Eduardo.

Best Regards,
Jun Li

Signed-off-by: Jun Li <junmuzi@gmail.com>
---
  target-i386/topology.h | 8 ++++++++
  1 file changed, 8 insertions(+)

diff --git a/target-i386/topology.h b/target-i386/topology.h
index 07a6c5f..ff21a98 100644
--- a/target-i386/topology.h
+++ b/target-i386/topology.h
@@ -126,6 +126,14 @@ static inline apic_id_t 
x86_apicid_from_cpu_idx(unsigned nr_cores,
                                                  unsigned cpu_index)
  {
      unsigned pkg_id, core_id, smt_id;
+
+    /* Check whether nr_cores and nr_threads is a power of 2.
+     * If not, 1 is assigned to them.
+     */
+    nr_cores = is_power_of_2(nr_cores) > 0 ? nr_cores : 1;
+    nr_threads = is_power_of_2(nr_threads) > 0 ? nr_threads : 1;
+
+
      x86_topo_ids_from_idx(nr_cores, nr_threads, cpu_index,
                            &pkg_id, &core_id, &smt_id);
      return apicid_from_topo_ids(nr_cores, nr_threads, pkg_id, core_id, 
smt_id);
-- 
1.8.3.1