From cefbba59925a01248b63ed85e0d0f96bfd1fed13 Mon Sep 17 00:00:00 2001
From: Kito Cheng <kito.cheng@sifive.com>
Date: Wed, 10 Jul 2019 01:54:14 -0700
Subject: [PATCH] Build newlib with POSIX mode

 - newlib was default to XOPEN MODE before 2018/12/6[1], but newlib
   decide to remove XOPEN mode SVID3 mode, and change the default IEEE
   mode.

 - The problem is IEEE won't set errno on several math function, so
   build with POSIX mode would be better for newlib.

 - For newlib nano, we might able to build with _IEEE_LIBM in future
   to reduce code size, and improve performance.

[1] https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;a=commit;h=b14a879d85b171960df789ac8ba2332004f838e0
---
 Makefile.in | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/Makefile.in b/Makefile.in
index c7938b72..12e39343 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -477,8 +477,8 @@ stamps/build-newlib: $(srcdir)/riscv-newlib stamps/build-gcc-newlib-stage1
 		--enable-newlib-io-long-long \
 		--enable-newlib-io-c99-formats \
 		--enable-newlib-register-fini \
-		CFLAGS_FOR_TARGET="-O2 $(CFLAGS_FOR_TARGET)" \
-		CXXFLAGS_FOR_TARGET="-O2 $(CXXFLAGS_FOR_TARGET)"
+		CFLAGS_FOR_TARGET="-O2 -D_POSIX_MODE $(CFLAGS_FOR_TARGET)" \
+		CXXFLAGS_FOR_TARGET="-O2 -D_POSIX_MODE $(CXXFLAGS_FOR_TARGET)"
 	$(MAKE) -C $(notdir $@)
 	$(MAKE) -C $(notdir $@) install
 	mkdir -p $(dir $@) && touch $@