use TARGET=ARMV8 when building OpenBLAS for aarch64/generic

easystacks/software.eessi.io/2023.06/rebuilds/20241017-eb-4.9.4-OpenBLAS-aarch64-generic.yml

@@ -0,0 +1,18 @@
+# 2024.10.17
+# TARGET=ARMV8 must be used when building OpenBLAS for aarch64/generic,
+# since otherwise "Illegal instruction" errors may happen in the driver part of OpenBLAS
+# on systems that only support a minimal instruction set like Arm v8 (like Raspberry Pi SBCs);
+# see also https://github.com/OpenMathLib/OpenBLAS/issues/4945
+easyconfigs:
+  - OpenBLAS-0.3.21-GCC-12.2.0.eb:
+      options:
+        # see https://github.com/easybuilders/easybuild-easyblocks/pull/3492
+        include-easyblocks-from-commit: d06d9617d9bfb63d338b6879eab9da81c8a312d8
+  - OpenBLAS-0.3.23-GCC-12.3.0.eb:
+      options:
+        # see https://github.com/easybuilders/easybuild-easyblocks/pull/3492
+        include-easyblocks-from-commit: d06d9617d9bfb63d338b6879eab9da81c8a312d8
+  - OpenBLAS-0.3.24-GCC-13.2.0.eb:
+      options:
+        # see https://github.com/easybuilders/easybuild-easyblocks/pull/3492
+        include-easyblocks-from-commit: d06d9617d9bfb63d338b6879eab9da81c8a312d8

eb_hooks.py

@@ -486,17 +486,33 @@ def pre_configure_hook_openblas_optarch_generic(self, *args, **kwargs):
     """
     Pre-configure hook for OpenBLAS: add DYNAMIC_ARCH=1 to build/test/install options when using --optarch=GENERIC
     """
+    # note: OpenBLAS easyblock was updated in https://github.com/easybuilders/easybuild-easyblocks/pull/3492
+    # to take care of this already, so at some point this hook can be removed...
     if self.name == 'OpenBLAS':
         if build_option('optarch') == OPTARCH_GENERIC:
+            dynamic_arch = 'DYNAMIC_ARCH=1'
             for step in ('build', 'test', 'install'):
-                self.cfg.update(f'{step}opts', "DYNAMIC_ARCH=1")
+                if dynamic_arch not in self.cfg[f'{step}opts']:
+                    self.cfg.update(f'{step}opts', dynamic_arch)
 
-            # use -mtune=generic rather than -mcpu=generic in $CFLAGS on aarch64,
-            # because -mcpu=generic implies a particular -march=armv* which clashes with those used by OpenBLAS
-            # when building with DYNAMIC_ARCH=1
             if get_cpu_architecture() == AARCH64:
-                cflags = os.getenv('CFLAGS').replace('-mcpu=generic', '-mtune=generic')
-                env.setvar('CFLAGS', cflags)
+                # when building for aarch64/generic, we also need to set TARGET=ARMV8 to make sure
+                # that the driver parts of OpenBLAS are compiled generically;
+                # see also https://github.com/OpenMathLib/OpenBLAS/issues/4945
+                target_armv8 = 'TARGET=ARMV8'
+                for step in ('build', 'test', 'install'):
+                    if target_armv8 not in self.cfg[f'{step}opts']:
+                        self.cfg.update(f'{step}opts', target_armv8)
+
+                # use -mtune=generic rather than -mcpu=generic in $CFLAGS for aarch64/generic,
+                # because -mcpu=generic implies a particular -march=armv* which clashes with those used by OpenBLAS
+                # when building with DYNAMIC_ARCH=1
+                mcpu_generic = '-mcpu=generic'
+                cflags = os.getenv('CFLAGS')
+                if mcpu_generic in cflags:
+                    cflags = cflags.replace(mcpu_generic, '-mtune=generic')
+                    self.log.info("Replaced -mcpu=generic with -mtune=generic in $CFLAGS")
+                    env.setvar('CFLAGS', cflags)
     else:
         raise EasyBuildError("OpenBLAS-specific hook triggered for non-OpenBLAS easyconfig?!")