From 86062515858aefe5f1f66b2a315aafa458999ede Mon Sep 17 00:00:00 2001
From: Alexey Neyman <stilor@att.net>
Date: Tue, 3 Mar 2020 16:37:31 -0800
Subject: Add --with-cpu= on 32-bit SPARC

... if building for GLIBC 2.31+.

Signed-off-by: Alexey Neyman <stilor@att.net>

diff --git a/config/libc/glibc.in b/config/libc/glibc.in
index c753359..f891392 100644
--- a/config/libc/glibc.in
+++ b/config/libc/glibc.in
@@ -35,11 +35,13 @@ config GLIBC_DEP_BINUTILS
     select BINUTILS_REQUIRE_2_25_or_later if GLIBC_2_26_or_later
     select BINUTILS_REQUIRE_older_than_2_30 if GLIBC_older_than_2_26 && ARCH_ARM && ARCH_64
 
+# Glibc 2.26 requires GCC4.9 or newer
 # Glibc 2.29 requires GCC5+ or, for ppc64le, GCC6.2+. We only support the latest
 # release on GCC6 branch, so just assume it is newer than 6.2
 # Glibc 2.30 uncondtionally requires GCC 6.2+
 config GLIBC_DEP_GCC
     def_bool y
+    select GCC_REQUIRE_4_9_or_later if GLIBC_2_26_or_later
     select GCC_REQUIRE_5_or_later if GLIBC_2_29_or_later
     select GCC_REQUIRE_6_or_later if GLIBC_2_29_or_later && ARCH_POWERPC && ARCH_64 && ARCH_LE
     select GCC_REQUIRE_6_or_later if GLIBC_2_30_or_later
@@ -64,9 +66,11 @@ config GLIBC_DEP_MAKE_4_0
     select MAKE_REQUIRE_4_0_or_later
     select MAKE_GNUMAKE_SYMLINK # Override old host make in .build/tools/bin
 
-config GLIBC_DEP_GCC
+# Glibc 2.31 removed support for pre-v8 SPARC in 32-bit mode (64-bit mode always
+# required UltraSPARC)
+config GLIBC_SPARC_ALLOW_V7
     def_bool y
-    select GCC_REQUIRE_4_9_or_later if GLIBC_2_26_or_later
+    depends on GLIBC_2_30_or_older
 
 config THREADS
     default "nptl"
diff --git a/scripts/build/arch/sparc.sh b/scripts/build/arch/sparc.sh
index 484687d..97c9b9d 100644
--- a/scripts/build/arch/sparc.sh
+++ b/scripts/build/arch/sparc.sh
@@ -3,21 +3,32 @@ CT_DoArchTupleValues() {
     # That's the only thing to override
     CT_TARGET_ARCH="sparc${target_bits_64}${CT_ARCH_SUFFIX}"
 
-    # By default, sparc64-*-linux is configured with -mcpu=v9. However,
-    # according to https://sourceware.org/ml/libc-alpha/2005-12/msg00027.html,
-    # "There is no Linux sparc64 port that runs on non-UltraSPARC-I+ ISA CPUs."
-    # There is a patch that would change the default to -mcpu=ultrasparc for
-    # sparc64-*-linux configuration: https://patchwork.ozlabs.org/patch/409424/
-    # but that patch has not been integrated (yet). One concern raised about
-    # this patch was that -mcpu=ultrasparc can suboptimally schedule instructions
-    # for newer SPARC CPUs. So, override to -mcpu=ultrasparc and warn the user.
-    if [ "${CT_KERNEL}" = "linux" -a "${CT_ARCH_64}" = "y" -a -z "${CT_ARCH_CPU}" ]; then
-        CT_DoLog WARN "Setting CPU to UltraSPARC-I for sparc64-linux. Set CT_ARCH_CPU if a different CPU is desired."
-        CT_ARCH_WITH_CPU="--with-cpu=ultrasparc"
-        if [ -n "${CT_ARCH_SUPPORTS_WITH_32_64}" -a -n "${CT_MULTILIB}" ]; then
-            CT_ARCH_WITH_CPU_32="--with-cpu-32=ultrasparc"
-            CT_ARCH_WITH_CPU_64="--with-cpu-64=ultrasparc"
-        fi
+    if [ "${CT_KERNEL}" = "linux" -a -z "${CT_ARCH_CPU}" ]; then
+	if [ "${CT_ARCH_64}" = "y" ]; then
+	    # By default, sparc64-*-linux is configured with -mcpu=v9. However,
+	    # according to https://sourceware.org/ml/libc-alpha/2005-12/msg00027.html,
+	    # "There is no Linux sparc64 port that runs on non-UltraSPARC-I+ ISA CPUs."
+	    # There is a patch that would change the default to -mcpu=ultrasparc for
+	    # sparc64-*-linux configuration: https://patchwork.ozlabs.org/patch/409424/
+	    # but that patch has not been integrated (yet). One concern raised about
+	    # this patch was that -mcpu=ultrasparc can suboptimally schedule instructions
+	    # for newer SPARC CPUs. So, override to -mcpu=ultrasparc and warn the user.
+	    CT_DoLog WARN "Setting CPU to UltraSPARC-I for sparc64-linux. Set CT_ARCH_CPU if a different CPU is desired."
+	    CT_ARCH_WITH_CPU="--with-cpu=ultrasparc"
+	    if [ -n "${CT_ARCH_SUPPORTS_WITH_32_64}" -a -n "${CT_MULTILIB}" ]; then
+		CT_ARCH_WITH_CPU_32="--with-cpu-32=ultrasparc"
+		CT_ARCH_WITH_CPU_64="--with-cpu-64=ultrasparc"
+	    fi
+	else
+	    # Similarly, sparc-*-linux defaults to v7. GLIBC 2.31 started to reject
+	    # pre-v8 configurations with 2.31, and default v8 fails a subsequent test for
+	    # using atomics (which are presumably, only available on some v8 CPUs).
+	    # Therefore, default to v9.
+	    if [ -z "${CT_GLIBC_SPARC_ALLOW_V7}" ]; then
+		CT_DoLog WARN "Setting CPU to V9 for sparc-linux. Set CT_ARCH_CPU if a different CPU is desired."
+		CT_ARCH_WITH_CPU="--with-cpu=v9"
+	    fi
+	fi
     fi
 }
 
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