external toolchain: add arbitrary arguments to sysroot discovery and toolchain wrapper

CodeSourcery uses non-standard arguments to determine which sysroot to use and to set other optimizations (e.g. which floating point ABI to use). This patch allows one to pass an arbitrary argument to the sysroot discovery in ext-tool.mk and adds the same option to the argument list in ext-toolchain-wrapper.c. I have not tested it with an empty option. Use at your own risk as this is my first open-source patch ever... (Am I supposed to write 'signed-off by...'?)

Cheers,
Matias

b/toolchain/toolchain-external/Config.in
index ca9892b..3b8ed2c 100644

@@ -125,6 +125,14 @@ config BR2_TOOLCHAIN_EXTERNAL_PATH
      help
        Path to where the external toolchain is installed.
 
+config BR2_TOOLCHAIN_EXTERNAL_CUSTOM_ARGS
+    string "Custom toolchain arguments (e.g. for selecting 

sysroot/optimizations)"
+ default ""
+ help

+      These arguments will be passed to the external toolchain
+      to determine its sysroot, and also passed to the toolchain
+      when calling the wrapper generated in $(HOST_DIR)/usr/bin.

+
config BR2_TOOLCHAIN_EXTERNAL_CUSTOM_PREFIX
string "Toolchain prefix"
depends on BR2_TOOLCHAIN_EXTERNAL_CUSTOM

b/toolchain/toolchain-external/ext-tool.mk
index 328f908..019bf30 100644

@@ -132,6 +132,10 @@ CC_TARGET_ABI_:=$(call qstrip,$(BR2_GCC_TARGET_ABI))
 
  # march/mtune/floating point mode needs to be passed to the external 

toolchain

  # to select the right multilib variant
+ifneq ($(BR2_TOOLCHAIN_EXTERNAL_CUSTOM_ARGS),)
+TOOLCHAIN_EXTERNAL_CFLAGS += $(BR2_TOOLCHAIN_EXTERNAL_CUSTOM_ARGS)
+TOOLCHAIN_EXTERNAL_WRAPPER_ARGS += 
-DBR_OPT='$(BR2_TOOLCHAIN_EXTERNAL_CUSTOM_ARGS)'
+endif
  ifneq ($(CC_TARGET_TUNE_),)
  TOOLCHAIN_EXTERNAL_CFLAGS += -mtune=$(CC_TARGET_TUNE_)
  TOOLCHAIN_EXTERNAL_WRAPPER_ARGS += -DBR_TUNE='"$(CC_TARGET_TUNE_)"'

b/toolchain/toolchain-external/ext-toolchain-wrapper.c index a485e74..2fc22c4 100644

@@ -22,6 +22,9 @@ static char path[PATH_MAX] = BR_CROSS_PATH;
  static char *args[MAXARGS] = {
      path,
      "--sysroot", BR_SYSROOT,
+#ifdef BR_OPT
+    BR_OPT,
+#endif /* BR_OPT */
  #ifdef BR_ARCH
      "-march=" BR_ARCH,
  #endif /* BR_ARCH */

	*Matias Garcia*
/Embedded Software Developer/
Ross Video | Live Production Technology
www.rossvideo.com <http://www.rossvideo.com>

Hello Mathias,

While the goal is correct, I don't like this implementation. The toolchain wrapper should just make use of the flags in BR2_TARGET_OPTIMIZATION configuration option, and not only -march, -mtune, -mabi, etc. options which are currently being used.

Regards,

Thomas

Thomas Petazzoni, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com

Hi Thomas,

I thought of that first, but I figured BR2_TARGET_OPTIMIZATION may be used for flags you wouldn't want sent to the linker (for example) in EVERY circumstance. In other words, I thought the wrapper ought to be for sysroot selection primarily. If you disagree, I'd be glad to change it.

Any other comments?

What's the usual procedure for submitting patches? I didn't find one on the website. I also see most people have a file summary at the top.

Cheers,
Matias

Hello Matias,

Please keep the Buildroot list in the loop for Buildroot-related discussions.

I'm still not a big fan of adding a different config option than BR2_TARGET_OPTIMIZATION that would be specific to the external toolchain case. But I haven't dug into the issue enough to propose a solution.

Thomas

Thomas Petazzoni, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com

Will do. I sent a reply to the list last time and no-one replied...

Here's the patch simplified to use only BR2_TARGET_OPTIMIZATION. Again, I don't know any fancy ways to post patches, so it's just the git diff. I moved the optimizations to the end of the wrapper so that you can supersede any of the build-in stuff if you want, at your peril.

Matias
--
Patch to add BR2_TARGET_OPTIMIZATION to the external toolchain wrapper.

b/toolchain/toolchain-external/ext-tool.mk
index 328f908..ad95d21 100644

@@ -132,6 +132,10 @@ CC_TARGET_ABI_:=$(call qstrip,

$(BR2_GCC_TARGET_ABI))

 # march/mtune/floating point mode needs to be passed to the external
toolchain
 # to select the right multilib variant
+ifneq ($(BR2_TARGET_OPTIMIZATION),)
+TOOLCHAIN_EXTERNAL_CFLAGS += $(BR2_TARGET_OPTIMIZATION)
+TOOLCHAIN_EXTERNAL_WRAPPER_ARGS +=
-DBR_OPT='$(BR2_TARGET_OPTIMIZATION)'
+endif
 ifneq ($(CC_TARGET_TUNE_),)
 TOOLCHAIN_EXTERNAL_CFLAGS += -mtune=$(CC_TARGET_TUNE_)
 TOOLCHAIN_EXTERNAL_WRAPPER_ARGS += -DBR_TUNE='"$(CC_TARGET_TUNE_)"'

b/toolchain/toolchain-external/ext-toolchain-wrapper.c index a485e74..dfa4fba 100644

@@ -37,6 +37,9 @@ static char *args[MAXARGS] = {
 #ifdef BR_VFPFLOAT
 	"-mfpu=vfp",
 #endif /* BR_VFPFLOAT */
+#ifdef BR_OPT
+	BR_OPT,
+#endif /* BR_OPT */
 };
 
 static const char *get_basename(const char *name)b

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