diff --git a/UPDATING b/UPDATING
--- a/UPDATING
+++ b/UPDATING
@@ -27,6 +27,10 @@
 	world, or to merely disable the most expensive debugging functionality
 	at runtime, run "ln -s 'abort:false,junk:false' /etc/malloc.conf".)
 
+20230803:
+	MAXCPU has been increased to 1024 in the amd64 GENERIC kernel config.
+	Out-of-tree kernel modules will need to be rebuilt.
+
 20230724:
 	CAM has been mechanically updated s/u_int(64|32|16|8)_t/uint\1_t/g
 	to move to the standard uintXX_t types from the old, traditional
diff --git a/sys/amd64/include/param.h b/sys/amd64/include/param.h
--- a/sys/amd64/include/param.h
+++ b/sys/amd64/include/param.h
@@ -65,7 +65,7 @@
 
 #ifdef SMP
 #ifndef MAXCPU
-#define MAXCPU		256
+#define MAXCPU		1024
 #endif
 #else
 #define MAXCPU		1