Trying to build Zero on linux-sparc initially fails with:

=== Output from failing command(s) repeated here ===
/usr/bin/printf "* For target hotspot_variant-zero_libjvm_objs_oopMap.o:\n"
* For target hotspot_variant-zero_libjvm_objs_oopMap.o:
(/bin/grep -v -e "^Note: including file:" < /home/glaubitz/openjdk/hs/build/linux-sparcv9-normal-zero-release/make-support/failure-logs/hotspot_variant-zero_libjvm_objs_oopMap.o.log || true) | /usr/bin/head -n 12
/home/glaubitz/openjdk/hs/hotspot/src/share/vm/compiler/oopMap.cpp:44:10: fatal error: vmreg_sparc.inline.hpp: No such file or directory
 #include "vmreg_sparc.inline.hpp"
          ^~~~~~~~~~~~~~~~~~~~~~~~
compilation terminated.
if test `/usr/bin/wc -l < /home/glaubitz/openjdk/hs/build/linux-sparcv9-normal-zero-release/make-support/failure-logs/hotspot_variant-zero_libjvm_objs_oopMap.o.log` -gt 12; then /bin/echo " ... (rest of output omitted)" ; fi
/usr/bin/printf "\n* All command lines available in /home/glaubitz/openjdk/hs/build/linux-sparcv9-normal-zero-release/make-support/failure-logs.\n"

* All command lines available in /home/glaubitz/openjdk/hs/build/linux-sparcv9-normal-zero-release/make-support/failure-logs.
/usr/bin/printf "=== End of repeated output ===\n"
=== End of repeated output ===

This can be alleviated with the following change:

diff -r eed8aa5e12df src/share/vm/compiler/oopMap.cpp
--- a/src/share/vm/compiler/oopMap.cpp Tue Aug 22 08:37:17 2017 -0400
+++ b/src/share/vm/compiler/oopMap.cpp Tue Aug 22 17:41:51 2017 +0300
@@ -40,7 +40,7 @@
 #ifdef COMPILER2
 #include "opto/optoreg.hpp"
 #endif
-#ifdef SPARC
+#if defined (SPARC) && !defined(ZERO)
 #include "vmreg_sparc.inline.hpp"
 #endif

After that, it will still fail with:

=== Output from failing command(s) repeated here ===
/usr/bin/printf "* For target hotspot_variant-zero_libjvm_gtest_objs_BUILD_GTEST_LIBJVM_link:\n"
* For target hotspot_variant-zero_libjvm_gtest_objs_BUILD_GTEST_LIBJVM_link:
(/bin/grep -v -e "^Note: including file:" < /home/glaubitz/openjdk/hs/build/linux-sparcv9-normal-zero-release/make-support/failure-logs/hotspot_variant-zero_libjvm_gtest_objs_BUILD_GTEST_LIBJVM_link.log || true) | /usr/bin/head -n 12
/home/glaubitz/openjdk/hs/build/linux-sparcv9-normal-zero-release/hotspot/variant-zero/libjvm/gtest/objs/test_memset_with_concurrent_readers.o: In function `gc_memset_with_concurrent_readers_test_Test::TestBody()':
/home/glaubitz/openjdk/hs/hotspot/test/native/gc/shared/test_memset_with_concurrent_readers.cpp:66: undefined reference to `memset_with_concurrent_readers(void*, int, unsigned long)'
/home/glaubitz/openjdk/hs/build/linux-sparcv9-normal-zero-release/hotspot/variant-zero/libjvm/objs/blockOffsetTable.o: In function `BlockOffsetSharedArray::fill_range(unsigned long, unsigned long, unsigned char)':
/home/glaubitz/openjdk/hs/hotspot/src/share/vm/gc/shared/blockOffsetTable.hpp:159: undefined reference to `memset_with_concurrent_readers(void*, int, unsigned long)'
/home/glaubitz/openjdk/hs/hotspot/src/share/vm/gc/shared/blockOffsetTable.hpp:159: undefined reference to `memset_with_concurrent_readers(void*, int, unsigned long)'
/home/glaubitz/openjdk/hs/hotspot/src/share/vm/gc/shared/blockOffsetTable.hpp:159: undefined reference to `memset_with_concurrent_readers(void*, int, unsigned long)'
/home/glaubitz/openjdk/hs/hotspot/src/share/vm/gc/shared/blockOffsetTable.hpp:159: undefined reference to `memset_with_concurrent_readers(void*, int, unsigned long)'
/home/glaubitz/openjdk/hs/build/linux-sparcv9-normal-zero-release/hotspot/variant-zero/libjvm/objs/blockOffsetTable.o:/home/glaubitz/openjdk/hs/hotspot/src/share/vm/gc/shared/blockOffsetTable.hpp:159: more undefined references to `memset_with_concurrent_readers(void*, int, unsigned long)' follow
collect2: error: ld returned 1 exit status
if test `/usr/bin/wc -l < /home/glaubitz/openjdk/hs/build/linux-sparcv9-normal-zero-release/make-support/failure-logs/hotspot_variant-zero_libjvm_gtest_objs_BUILD_GTEST_LIBJVM_link.log` -gt 12; then /bin/echo " ... (rest of output omitted)" ; fi
/usr/bin/printf "* For target hotspot_variant-zero_libjvm_objs_BUILD_LIBJVM_link:\n"
* For target hotspot_variant-zero_libjvm_objs_BUILD_LIBJVM_link:
(/bin/grep -v -e "^Note: including file:" < /home/glaubitz/openjdk/hs/build/linux-sparcv9-normal-zero-release/make-support/failure-logs/hotspot_variant-zero_libjvm_objs_BUILD_LIBJVM_link.log || true) | /usr/bin/head -n 12
/home/glaubitz/openjdk/hs/build/linux-sparcv9-normal-zero-release/hotspot/variant-zero/libjvm/objs/blockOffsetTable.o: In function `BlockOffsetSharedArray::fill_range(unsigned long, unsigned long, unsigned char)':
/home/glaubitz/openjdk/hs/hotspot/src/share/vm/gc/shared/blockOffsetTable.hpp:159: undefined reference to `memset_with_concurrent_readers(void*, int, unsigned long)'
/home/glaubitz/openjdk/hs/hotspot/src/share/vm/gc/shared/blockOffsetTable.hpp:159: undefined reference to `memset_with_concurrent_readers(void*, int, unsigned long)'
/home/glaubitz/openjdk/hs/hotspot/src/share/vm/gc/shared/blockOffsetTable.hpp:159: undefined reference to `memset_with_concurrent_readers(void*, int, unsigned long)'
/home/glaubitz/openjdk/hs/hotspot/src/share/vm/gc/shared/blockOffsetTable.hpp:159: undefined reference to `memset_with_concurrent_readers(void*, int, unsigned long)'
/home/glaubitz/openjdk/hs/hotspot/src/share/vm/gc/shared/blockOffsetTable.hpp:159: undefined reference to `memset_with_concurrent_readers(void*, int, unsigned long)'
/home/glaubitz/openjdk/hs/build/linux-sparcv9-normal-zero-release/hotspot/variant-zero/libjvm/objs/blockOffsetTable.o:/home/glaubitz/openjdk/hs/hotspot/src/share/vm/gc/shared/blockOffsetTable.hpp:159: more undefined references to `memset_with_concurrent_readers(void*, int, unsigned long)' follow
collect2: error: ld returned 1 exit status
if test `/usr/bin/wc -l < /home/glaubitz/openjdk/hs/build/linux-sparcv9-normal-zero-release/make-support/failure-logs/hotspot_variant-zero_libjvm_objs_BUILD_LIBJVM_link.log` -gt 12; then /bin/echo " ... (rest of output omitted)" ; fi
/usr/bin/printf "\n* All command lines available in /home/glaubitz/openjdk/hs/build/linux-sparcv9-normal-zero-release/make-support/failure-logs.\n"

* All command lines available in /home/glaubitz/openjdk/hs/build/linux-sparcv9-normal-zero-release/make-support/failure-logs.
/usr/bin/printf "=== End of repeated output ===\n"
=== End of repeated output ===

which again can be fixed with:

diff -r eed8aa5e12df src/share/vm/gc/shared/memset_with_concurrent_readers.hpp
--- a/src/share/vm/gc/shared/memset_with_concurrent_readers.hpp Tue Aug 22 08:37:17 2017 -0400
+++ b/src/share/vm/gc/shared/memset_with_concurrent_readers.hpp Tue Aug 22 17:41:51 2017 +0300
@@ -37,7 +37,7 @@
 // understanding that there may be concurrent readers of that memory.
 void memset_with_concurrent_readers(void* to, int value, size_t size);
 
-#ifdef SPARC
+#if defined(SPARC) && !defined(ZERO)
 
 // SPARC requires special handling. See SPARC-specific definition.

With both changes, the Zero build succeeds without any problems. I am not sure yet, however, whether the above changes are rather a bad workaround or the acceptable fix.

Build with:

sh ./configure && make clean CONF=linux-sparcv9-normal-zero-release && MAKE_VERBOSE=y QUIETLY= LOG=debug sh ./configure --with-jvm-variants=zero --with-boot-jdk=/usr/lib/jvm/java-9-openjdk-sparc64 --disable-precompiled-headers --with-debug-level=release --disable-warnings-as-errors --disable-javac-server --with-num-cores=16 && make JOBS=16 MAKE_VERBOSE=y QUIETLY= LOG=debug CONF=linux-sparcv9-normal-zero-release