diff --git a/include/haproxy/cpu_topo-t.h b/include/haproxy/cpu_topo-t.h
new file mode 100644
index 000000000..b733d11d1
--- /dev/null
+++ b/include/haproxy/cpu_topo-t.h
@@ -0,0 +1,44 @@
+#ifndef _HAPROXY_CPU_TOPO_T_H
+#define _HAPROXY_CPU_TOPO_T_H
+
+#include <haproxy/api-t.h>
+#include <haproxy/cpuset-t.h>
+
+/* CPU state flags used with CPU topology detection (ha_cpu_topo.st). We try
+ * hard to rely on known info. For example we don't claim a CPU is bound or
+ * online if we don't know, reason why instead we store offline or excluded.
+ * Other flags like DONT_USE indicate a user's choice while IGNORED indicates
+ * the result of an automated selection. Two marks are available for allocation
+ * algorithms to temporarily compare/select/evict CPUs. These must be cleared
+ * after use.
+ */
+#define HA_CPU_F_EXCLUDED     0x0001  // this CPU was excluded at boot
+#define HA_CPU_F_OFFLINE      0x0002  // this CPU is known to be offline
+#define HA_CPU_F_DONT_USE     0x0004  // this CPU must not be used
+#define HA_CPU_F_IGNORED      0x0008  // this CPU will not be used
+#define HA_CPU_F_EXCL_MASK    0x000F  // mask of bits that exclude a CPU
+#define HA_CPU_F_MARK1        0x0010  // for temporary internal use only
+#define HA_CPU_F_MARK2        0x0020  // for temporary internal use only
+#define HA_CPU_F_MARK_MASK    0x0030  // mask to drop the two marks above
+
+/* CPU topology descriptor. All the ID and IDX fields are initialized to -1
+ * when not known. The identifiers there are mostly assigned on the fly using
+ * increments and have no particular representation except the fact that CPUs
+ * having the same ID there share the same designated resource. The flags are
+ * preset to zero.
+ */
+struct ha_cpu_topo {
+	ushort st;    // state flags (HA_CPU_F_*)
+	short idx;    // CPU index as passed to the OS. Initially the entry index.
+	short ca_id[5]; // cache ID for each level (L0 to L4)
+	short ts_id;  // thread-set identifier (generally core number)
+	short cl_gid; // cluster global identifier (group of more intimate cores)
+	short cl_lid; // cluster local identifier (per {pkg,node})
+	short no_id;  // NUMA node identifier
+	short pk_id;  // package identifier
+	short th_cnt; // number of siblings threads
+	short th_id;  // thread ID among siblings of the same core
+	short capa;   // estimated CPU relative capacity; more is better
+};
+
+#endif /* _HAPROXY_CPU_TOPO_T_H */