--- SConstruct.orig	2022-05-17 13:56:34 UTC
+++ SConstruct
@@ -1301,9 +1301,9 @@ if has_option('variables-help'):
     print(env_vars.GenerateHelpText(env))
     Exit(0)
 
-unknown_vars = env_vars.UnknownVariables()
-if unknown_vars:
-    env.FatalError("Unknown variables specified: {0}", ", ".join(list(unknown_vars.keys())))
+#unknown_vars = env_vars.UnknownVariables()
+#if unknown_vars:
+#    env.FatalError("Unknown variables specified: {0}", ", ".join(list(unknown_vars.keys())))
 
 if get_option('install-action') != 'default' and get_option('ninja') != "disabled":
     env.FatalError("Cannot use non-default install actions when generating Ninja.")
@@ -2370,13 +2370,13 @@ if env.TargetOSIs('posix'):
             # If runtime hardening is requested, then build anything
             # destined for an executable with the necessary flags for PIE.
             env.AppendUnique(
-                PROGCCFLAGS=['-fPIE'],
+                PROGCCFLAGS=['-fpic'],
                 PROGLINKFLAGS=['-pie'],
             )
 
     # -Winvalid-pch Warn if a precompiled header (see Precompiled Headers) is found in the search path but can't be used.
     env.Append( CCFLAGS=["-fasynchronous-unwind-tables",
-                         "-ggdb" if not env.TargetOSIs('emscripten') else "-g",
+    #                    "-ggdb" if not env.TargetOSIs('emscripten') else "-g",
                          "-Wall",
                          "-Wsign-compare",
                          "-Wno-unknown-pragmas",
@@ -2541,8 +2541,12 @@ if not env.TargetOSIs('windows', 'macOS') and (env.Too
     # setting it for both C and C++ by setting both of CFLAGS and
     # CXXFLAGS.
 
+    arm_march_flag = "armv8-a"
+    if get_option('use-hardware-crc32') == "on":
+        arm_march_flag += "+crc"
+
     default_targeting_flags_for_architecture = {
-        "aarch64"    : { "-march=" : "armv8.2-a",    "-mtune=" : "generic"                        },
+        "aarch64"    : { "-march=" : arm_march_flag, "-mtune=" : "generic"                        },
         "i386"       : { "-march=" : "nocona",       "-mtune=" : "generic"                        },
         "ppc64le"    : { "-mcpu="  : "power8",       "-mtune=" : "power8", "-mcmodel=" : "medium" },
         "s390x"      : { "-march=" : "z196",         "-mtune=" : "zEC12"                          },
@@ -2554,7 +2558,7 @@ if not env.TargetOSIs('windows', 'macOS') and (env.Too
     if "sandybridge" in selected_experimental_optimizations:
         default_targeting_flags_for_architecture["x86_64"] = {
             "-march="                : "sandybridge",
-            "-mtune="                : "generic",
+    #       "-mtune="                : "generic",
             "-mprefer-vector-width=" : "128",
         }