Make libcpuid dependency optional with --disable-cpuid

configure.ac

@@ -195,10 +195,17 @@ PKG_CHECK_MODULES([SODIUM], [libsodium], [CXXFLAGS="$SODIUM_CFLAGS $CXXFLAGS"])
 PKG_CHECK_MODULES([LIBBROTLI], [libbrotlienc libbrotlidec], [CXXFLAGS="$LIBBROTLI_CFLAGS $CXXFLAGS"])
 
 # Look for libcpuid.
+have_libcpuid=
 if test "$machine_name" = "x86_64"; then
-  PKG_CHECK_MODULES([LIBCPUID], [libcpuid], [CXXFLAGS="$LIBCPUID_CFLAGS $CXXFLAGS"])
-  have_libcpuid=1
-  AC_DEFINE([HAVE_LIBCPUID], [1], [Use libcpuid])
+    AC_ARG_ENABLE([cpuid],
+                  AS_HELP_STRING([--disable-cpuid], [Do not determine microarchitecture levels with libcpuid (relevant to x86_64 only)]))
+    if test "x$enable_cpuid" != "xno"; then
+      PKG_CHECK_MODULES([LIBCPUID], [libcpuid],
+        [CXXFLAGS="$LIBCPUID_CFLAGS $CXXFLAGS"
+         have_libcpuid=1
+         AC_DEFINE([HAVE_LIBCPUID], [1], [Use libcpuid])]
+      )
+    fi
 fi
 AC_SUBST(HAVE_LIBCPUID, [$have_libcpuid])
 

doc/manual/src/installation/prerequisites-source.md

@@ -64,3 +64,5 @@
     (e.g., as whether to have `x86_64-v2-linux` among additional system types).
     The library is available from its homepage
     <http://libcpuid.sourceforge.net>.
+    This is an optional dependency and can be disabled
+    by providing a `--disable-cpuid` to the `configure` script.

tests/local.mk

@@ -48,7 +48,6 @@ nix_tests = \
   flakes.sh \
   flake-local-settings.sh \
   build.sh \
-  compute-levels.sh \
   repl.sh ca/repl.sh \
   ca/build.sh \
   ca/build-with-garbage-path.sh \
@@ -63,6 +62,10 @@ nix_tests = \
   eval-store.sh
   # parallel.sh
 
+ifeq ($(HAVE_LIBCPUID), 1)
+	nix_tests += compute-levels.sh
+endif
+
 install-tests += $(foreach x, $(nix_tests), tests/$(x))
 
 tests-environment = NIX_REMOTE= $(bash) -e