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

[jun muzi <junmuzi@gmail.com>]

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As Peter's suggestion, mv this patch to file target-i386/topology.h. If
someone has any good idea, please give me a commit in the followings.
Thanks.
---
 target-i386/topology.h | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/target-i386/topology.h b/target-i386/topology.h
index 07a6c5f..cda6bf5 100644
--- a/target-i386/topology.h
+++ b/target-i386/topology.h
@@ -117,6 +117,19 @@ static inline void x86_topo_ids_from_idx(unsigned
nr_cores,
     *pkg_id = core_index / nr_cores;
 }

+/* This function will return whether @num is power of 2.
+ *
+ * Returns: 1 indicate @num is power of 2, 0 indicate @num is not.
+ */
+static int is_2_power(int num)
+{
+    if (num < 0 || num > 256) {
+        return 1;
+    }
+
+    return !(num & (num - 1));
+}
+
 /* Make APIC ID for the CPU 'cpu_index'
  *
  * 'cpu_index' is a sequential, contiguous ID for the CPU.
@@ -126,6 +139,13 @@ 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 (!is_2_power(smp_cores) || !is_2_power(smp_threads)) {
+        nr_cores = 1;
+        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);
-- 
1.8.1.4
-- 
Jun Li <junmuzi@gmail.com>

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