Added "--with-sky130-variants=" to the configuration, so that the
compile and install can be restricted to only sky130A or sky130B.
The default is to compile and install both variants, equivalent to
"--with-sky130-variants=all".

scripts/configure

diff --git a/scripts/configure b/scripts/configure
index 5ccc6d5..29224d0 100755
--- a/scripts/configure
+++ b/scripts/configure
@@ -607,6 +607,7 @@
 KLAYOUT_DISABLED
 ALL_TECHS
 SKY130_SOURCE_PATH
+SKY130_ENABLED_VARIANTS
 SKY130_LINK_TARGETS
 SED
 pkgpyexecdir
@@ -661,6 +662,7 @@
 enable_option_checking
 enable_sky130_pdk
 with_sky130_link_targets
+with_sky130_variants
 enable_klayout
 enable_magic
 enable_netgen
@@ -1346,6 +1348,9 @@
   --with-sky130-link-targets=none|source
                           "make symbolic links to existing files
                           [default=none]"
+  --with-sky130-variants=all|A|B|...
+                          "compile/install specified PDK variants only
+                          [default=all]"
   --with-ef-style         Use efabless style file system structure
                           [default=no]
 
@@ -2186,6 +2191,7 @@
         echo "Checking technology sky130..."
 
 
+        SKY130_ENABLED_VARIANTS="all"
         SKY130_SOURCE_PATH=""
         SKY130_LINK_TARGETS="none"
         SKY130_AUTO="0"
@@ -2262,6 +2268,18 @@
 
             { $as_echo "$as_me:${as_lineno-$LINENO}: Link targets set to $SKY130_LINK_TARGETS" >&5
 $as_echo "$as_me: Link targets set to $SKY130_LINK_TARGETS" >&6;}
+
+            # --with-pdk-variants=PDK_ENABLED_VARIANTS
+
+# Check whether --with-sky130-variants was given.
+if test "${with_sky130_variants+set}" = set; then :
+  withval=$with_sky130_variants; SKY130_ENABLED_VARIANTS=$with_sky130_variants
+
+fi
+
+
+            { $as_echo "$as_me:${as_lineno-$LINENO}: Enabled variants set to $SKY130_ENABLED_VARIANTS" >&5
+$as_echo "$as_me: Enabled variants set to $SKY130_ENABLED_VARIANTS" >&6;}
         fi
 
 
@@ -2269,6 +2287,7 @@
 
 
 
+
 # Export the list of known technologies to the Makefile
 ALL_TECHS="sky130"
 

scripts/configure.ac

diff --git a/scripts/configure.ac b/scripts/configure.ac
index 7f1ba4b..940362d 100755
--- a/scripts/configure.ac
+++ b/scripts/configure.ac
@@ -41,6 +41,7 @@
         echo "Checking technology pdk..."
         m4_define([pdkvar], [m4_normalize(m4_esyscmd(echo pdk | tr "a-z-" "A-Z_"))])
 
+        pdkvar[]_ENABLED_VARIANTS="all"
         pdkvar[]_SOURCE_PATH=""
         pdkvar[]_LINK_TARGETS="none"
         pdkvar[]_AUTO="0"
@@ -88,10 +89,19 @@
             )
             AC_SUBST([]pdkvar[]_LINK_TARGETS)
             AC_MSG_NOTICE([Link targets set to $pdkvar[]_LINK_TARGETS])
+
+            # --with-pdk-variants=PDK_ENABLED_VARIANTS
+            AC_ARG_WITH(pdk-variants,
+                [AS_HELP_STRING([--with-pdk-variants=all|A|B|...], "compile/install specified PDK variants only @<:@default=all@:>@")],
+                [[]pdkvar[]_ENABLED_VARIANTS=$with_[]pdk[]_variants]
+            )
+            AC_SUBST([]pdkvar[]_ENABLED_VARIANTS)
+            AC_MSG_NOTICE([Enabled variants set to $pdkvar[]_ENABLED_VARIANTS])
         fi
 
         AC_SUBST(pdkvar[]_SOURCE_PATH)
         AC_SUBST(pdkvar[]_LINK_TARGETS)
+        AC_SUBST(pdkvar[]_ENABLED_VARIANTS)
     ])
 ])
 

sky130/Makefile.in

diff --git a/sky130/Makefile.in b/sky130/Makefile.in
index 7edf57f..92f9fd5 100644
--- a/sky130/Makefile.in
+++ b/sky130/Makefile.in
@@ -113,6 +113,7 @@
 #	SKYWATER_PATH: Points to vendor sources
 #	EF_STYLE: 1 for efabless style, 0 otherwise
 #	LINK_TARGETS_A: If "source", link back to source when possible
+#	ENABLED_VARIANTS: If not "all", then compile/install only the specified variants
 #
 # Run "make" to stage the PDK for tool setup and vendor libraries
 #
@@ -192,6 +193,18 @@
 LINK_TARGETS_A = @SKY130_LINK_TARGETS@
 LINK_TARGETS_B = sky130A
 
+# ENABLED_VARIANTS = all | A | B
+ENABLED_VARIANTS = @SKY130_ENABLED_VARIANTS@
+ifeq (${ENABLED_VARIANTS},)
+	VARIANTS += A B
+else
+    ifeq (${ENABLED_VARIANTS}, all)
+	VARIANTS += A B
+    else
+	VARIANTS += ${ENABLED_VARIANTS}
+    endif
+endif
+
 # Paths:
 
 # Path to skywater_pdk
@@ -538,7 +551,7 @@
 	SPIEXT = spice
 endif
 
-all: all-A all-B
+all: $(foreach var, ${VARIANTS}, all-$(var))
 
 # Handle prerequisites (fetch and install the PDK and requested libraries)
 prerequisites: pdk-repo alpha-repo xschem-repo sram-repo osu-t12-repo osu-t15-repo osu-t18-repo
@@ -1461,7 +1474,7 @@
 			options=custom/scripts/gds_import_setup.tcl \
 		-library digital sky130_osu_sc_18t_ls 2>&1 | tee -a ${SKY130$*}_make.log
 
-install: install-A install-B
+install: $(foreach var, ${VARIANTS}, install-$(var))
 
 install-A:
 	echo "Starting SKY130 PDK migration on "`date` > ${SKY130A}_install.log
@@ -1481,7 +1494,7 @@
 		-link_from ${DIST_LINK_TARGETS_B} 2>&1 | tee -a ${SKY130B}_install.log
 	echo "Ended SKY130 PDK migration on "`date` >> ${SKY130B}_install.log
 
-uninstall: uninstall-A uninstall-B
+uninstall: $(foreach var, ${VARIANTS}, uninstall-$(var))
 
 uninstall-A:
 	echo "Uninstalling SKY130 PDK from ${SHARED_PDKS_PATH}"
@@ -1497,7 +1510,7 @@
 	fi
 	echo "Finished SKY130 PDK uninstall"
 
-clean: clean-A clean-B
+clean: $(foreach var, ${VARIANTS}, clean-$(var))
 
 clean-A:
 	${STAGE} -target ${STAGING_PATH}/${SKY130A} -clean
@@ -1505,7 +1518,7 @@
 clean-B:
 	${STAGE} -target ${STAGING_PATH}/${SKY130B} -clean
 
-veryclean: veryclean-A veryclean-B
+veryclean: $(foreach var, ${VARIANTS}, veryclean-$(var))
 
 veryclean-A: clean-A
 	${RM} ${SKY130A}_make.log