--- ./SConstruct.orig	2023-03-25 16:50:11.568918000 +0200
+++ ./SConstruct	2023-03-25 16:53:05.980989000 +0200
@@ -295,7 +295,7 @@
 )
 
 experimental_optimizations = [
-    'O3',
+    'O',
     'builtin-memcmp',
     'fnsi',
     'nofp',
@@ -313,7 +313,7 @@
     action="append",
     choices=experimental_optimization_choices,
     const=experimental_optimization_choices[0],
-    default=['+sandybridge'],
+    default=[''],
     help='Enable experimental optimizations',
     nargs='?',
     type='choice'
@@ -1343,9 +1343,9 @@
     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())))
 
 install_actions.setup(env, get_option('install-action'))
 
@@ -2435,13 +2435,12 @@
             # 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",
                          "-Wall",
                          "-Wsign-compare",
                          "-Wno-unknown-pragmas",
@@ -2566,7 +2565,7 @@
         )
 
     if optBuild and not optBuildForSize:
-        env.Append( CCFLAGS=["-O3" if "O3" in selected_experimental_optimizations else "-O2"] )
+        env.Append( CCFLAGS=["-O" if "O3" in selected_experimental_optimizations else "-O"] )
     elif optBuild and optBuildForSize:
         env.Append( CCFLAGS=["-Os"] )
     else:
@@ -2608,8 +2607,12 @@
     # 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"                          },