From b73a1c06386f43b0b0d7ce99448b8c55f4c5156c Mon Sep 17 00:00:00 2001
From: Alexander Sosedkin <monk@unboiled.info>
Date: Sun, 28 Nov 2021 00:47:25 +0100
Subject: [PATCH 1/2] Document libcpuid dependency

---
 doc/manual/src/installation/prerequisites-source.md | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/doc/manual/src/installation/prerequisites-source.md b/doc/manual/src/installation/prerequisites-source.md
index 0323a4f55..37e0b5a10 100644
--- a/doc/manual/src/installation/prerequisites-source.md
+++ b/doc/manual/src/installation/prerequisites-source.md
@@ -58,3 +58,9 @@
     `--disable-seccomp-sandboxing` option to the `configure` script (Not
     recommended unless your system doesn't support `libseccomp`). To get
     the library, visit <https://github.com/seccomp/libseccomp>.
+
+  - On 64-bit x86 machines only, `libcpuid` library
+    is used to determine which microarchitecture levels are supported
+    (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>.

From a9bd06d0ea2c7af9fa33763bdca174db76400ee0 Mon Sep 17 00:00:00 2001
From: Alexander Sosedkin <monk@unboiled.info>
Date: Sun, 28 Nov 2021 00:48:04 +0100
Subject: [PATCH 2/2] Make libcpuid dependency optional with --disable-cpuid

---
 configure.ac                                        | 13 ++++++++++---
 doc/manual/src/installation/prerequisites-source.md |  2 ++
 tests/local.mk                                      |  5 ++++-
 3 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/configure.ac b/configure.ac
index 65478ecc5..4108eb0a8 100644
--- a/configure.ac
+++ b/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])
 
diff --git a/doc/manual/src/installation/prerequisites-source.md b/doc/manual/src/installation/prerequisites-source.md
index 37e0b5a10..1b03bacd3 100644
--- a/doc/manual/src/installation/prerequisites-source.md
+++ b/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.
diff --git a/tests/local.mk b/tests/local.mk
index 6f38853bc..936b72c2a 100644
--- a/tests/local.mk
+++ b/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