From 9e29fe0abddd32da0f241bc11a2b007449ca8cfb Mon Sep 17 00:00:00 2001
From: Tido Klaassen <tido@4gh.eu>
Date: Wed, 14 Oct 2015 18:48:08 +0200
Subject: [PATCH] Debian newlib nano workaround - made use of newlib's nano
 version configurable by make variable USE_NANO - added paragraphs to
 README.md explaining how and when to use USE_NANO   and FIX_DEBIAN

---
 ports/cortex-m/Makefile  | 27 ++++++++++++++++++---------
 ports/cortex-m/README.md | 11 +++++++++++
 2 files changed, 29 insertions(+), 9 deletions(-)

diff --git a/ports/cortex-m/Makefile b/ports/cortex-m/Makefile
index 7b1824a..9cde99e 100644
--- a/ports/cortex-m/Makefile
+++ b/ports/cortex-m/Makefile
@@ -8,6 +8,21 @@ ifeq ($(V),)
     MAKEFLAGS += --no-print-directory
 endif
 
+# Use the size optimised nano version of newlib.
+# This usually is the version of newlib you want to use, although it has some
+# limitations, like printf not having support for floating point vars.
+# This relies on your newlib installation to provide a working nano.specs
+# file. On Debian you will need at least version 2.1.0+git20141201.db59ff3-2
+# of package libnewlib-arm-none-eabi
+USE_NANO    := true
+
+# Debian's libnewlib-arm-none-eabi package version 2.2.0+git20150830.5a3d536-1
+# ships with a buggy nano.specs file that does not set up a proper include
+# path for finding the nano version of newlib.h.
+# Also, the nano version has been built with the -fshort-wchar option, making
+# it incompatible with object files using the standard ABI.
+#FIX_DEBIAN  := true
+
 # Build directory
 ifdef O
     build_dir=$(shell readlink -f $(O))
@@ -136,21 +151,15 @@ LDLIBS		+= -l$(LIBNAME)
 NEWLIBS	    += -lc -lgcc
 
 ifneq ($(BOARD),qemu)
-# Use the size optimised nano version of newlib.
-# This usually is the version of newlib you want to use, although it has some
-# limitations, like printf not having support for floating point vars.
+ifeq ($(USE_NANO),true)
 SPECS       := -specs=nano.specs
 
-ifneq ($(FIX_DEBIAN),)
-# Debian's libnewlib-arm-none-eabi package version 2.2.0+git20150830.5a3d536-1
-# ships with a buggy nano.specs file that does not set up a proper include
-# path for finding the nano version of newlib.h.
-# Also, the nano version has been built with the -fshort-wchar option, making
-# it incompatible with object files using the standard ABI.
+ifeq ($(FIX_DEBIAN),true)
 SPECS       += -I/usr/include/newlib/nano
 LOCM3_FLAGS += -fshort-wchar
 CFLAGS      += -fshort-wchar
 endif
+endif
 
 # Uncomment to link against libnosys if you do not want to use the provided
 # stubs.
diff --git a/ports/cortex-m/README.md b/ports/cortex-m/README.md
index 7419e14..d02bb48 100644
--- a/ports/cortex-m/README.md
+++ b/ports/cortex-m/README.md
@@ -20,6 +20,17 @@ apt-get install gcc-arm-none-eabi binutils-arm-none-eabi
 apt-get install libnewlib-arm-none-eabi libnewlib-dev
 apt-get install openocd
 ```
+**N.B.** Usually you will want to compile and link against the size optimised
+"nano" version of newlib. This is done by default. If your version
+of newlib does not support this (Debian's libnewlib package version before
+2.1.0+git20141201.db59ff3-2) you will have to comment out the line
+`USE_NANO := true` in the Makefile or pass `USE_NANO=` as
+a command line option to make.
+
+**N.B.** Debian's libnewlib-arm-none-eabi version 2.2.0+git20150830.5a3d536-1
+ships with broken nano support. To enable necessary workarounds, uncomment
+the line `#FIX_DEBIAN := true` in the Makefile or pass `FIX_DEBIAN=true`
+as a command line option to make.
 
 ## Code Layout
 The "classic" port components (code needed for task set-up and context