From 2da84d90638723f673873f6e4b26ecf24186da60 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?King=20K=C3=A9vin?= <kingkevin@cuvoodoo.info>
Date: Fri, 8 Jun 2018 13:40:38 +0200
Subject: [PATCH] Rakefile: use gcc as linker instead of ld to profit from
 library finding

---
 Rakefile | 29 +++++++++++++----------------
 1 file changed, 13 insertions(+), 16 deletions(-)

diff --git a/Rakefile b/Rakefile
index 271eb17..4693088 100644
--- a/Rakefile
+++ b/Rakefile
@@ -30,8 +30,8 @@ SRC_DIRS = [".", "lib"]
 # cross-compiler environment
 PREFIX = ENV["PREFIX"] || "arm-none-eabi"
 CC = PREFIX+"-gcc"
-#CC = "clang -target #{PREFIX}" # to use clang instead of gcc
-LD = PREFIX+"-ld"
+# LD would be the proper linker, but gcc comes with essential library path finder
+LD = PREFIX+"-gcc"
 AR = PREFIX+"-ar"
 AS = PREFIX+"-as"
 OBJCOPY = PREFIX+"-objcopy"
@@ -64,24 +64,21 @@ cflags << "-DSTM32F1 -D#{BOARD}"
 cflags = cflags.compact*' '
 
 # linker flags
-ldflags = [ENV["LDFLAGS"]]
+ldflags = []
 # build static binary (no shared libraries on the micro-controller)
 ldflags << "-static"
 # don't include the system start files
 ldflags << "-nostartfiles"
+# linker specific flags
+ldflags_linker = [ENV["LDFLAGS"]]
 # only keep used sections
-ldflags << "--gc-sections"
-# add standard libraries (for libc, libm, libnosys, libgcc) because we don't use arm-none-eabi-gcc to locate them
-library_paths = ["/usr/arm-none-eabi/lib/armv7-m/", "/usr/lib/arm-none-eabi/lib/armv7-m/", "/usr/lib/gcc/arm-none-eabi/*/armv7-m/"]
-# add libopencm3
-library_paths += [LIBOPENCM3_LIB]
-# include libraries in flags
-ldflags += library_paths.collect {|library_path| "--library-path #{library_path}"}
-ldflags *= ' '
-# used libraries (gcc provides the ARM ABI)
-ldlibs = [STM32F1_LIB, "m", "c", "nosys", "gcc"]
-ldlibs = ldlibs.collect {|library| "--library #{library}"}
-ldlibs *= ' '
+ldflags_linker = ["--gc-sections"]
+# add libopencm3 libraries
+library_paths = [LIBOPENCM3_LIB]
+# project libraries
+ldlibs = [STM32F1_LIB]
+# general libraries (gcc provides the ARM ABI)
+ldlibs_linker = ["m", "c", "nosys", "gcc"]
 
 # target micro-controller information (ARM Cortex-M3 supports thumb and thumb2, but does not include a floating point unit)
 archflags = "-mthumb -mcpu=cortex-m3 -msoft-float"
@@ -155,7 +152,7 @@ end
 
 desc "link binary"
 rule '.elf' => ['.o', proc{|f| dependencies(f)}, '.ld', "#{LIBOPENCM3_LIB}/lib#{STM32F1_LIB}.a"] do |t|
-  sh "#{LD} #{ldflags} --script #{t.name.ext('ld')} #{t.prerequisites[0..-3].join(' ')} #{ldlibs} -o #{t.name}"
+  sh "#{LD} #{archflags} #{ldflags.join(' ')} #{t.prerequisites[0..-3].join(' ')} -T#{t.name.ext('ld')} #{ldflags_linker.collect{|flag| "-Wl,"+flag}.join(' ')} #{library_paths.collect{|path| "-L"+path}.join(' ')} #{ldlibs.collect{|lib| "-l"+lib}.join(' ')} -Wl,--start-group #{ldlibs_linker.collect{|lib| "-l"+lib}.join(' ')} -Wl,--end-group --output #{t.name}"
   sh "size #{t.name}"
 end