From 5e2be6ab3009688ccbe8fd4dac404ddfc38bcc08 Mon Sep 17 00:00:00 2001
From: Giovanni Di Sirio <gdisirio@gmail.com>
Date: Tue, 15 Nov 2016 10:18:14 +0000
Subject: [PATCH] Fixed bug #789.

git-svn-id: svn://svn.code.sf.net/p/chibios/svn/trunk@9907 35acf78f-673a-0410-8e92-d51de3d6d3f4
---
 os/various/syscalls.c | 7 +++++++
 readme.txt            | 2 ++
 2 files changed, 9 insertions(+)

diff --git a/os/various/syscalls.c b/os/various/syscalls.c
index d4be50019..d4f6429cc 100644
--- a/os/various/syscalls.c
+++ b/os/various/syscalls.c
@@ -67,6 +67,7 @@
 
 /***************************************************************************/
 
+__attribute__((used))
 int _read_r(struct _reent *r, int file, char * ptr, int len)
 {
   (void)r;
@@ -88,6 +89,7 @@ int _read_r(struct _reent *r, int file, char * ptr, int len)
 
 /***************************************************************************/
 
+__attribute__((used))
 int _lseek_r(struct _reent *r, int file, int ptr, int dir)
 {
   (void)r;
@@ -100,6 +102,7 @@ int _lseek_r(struct _reent *r, int file, int ptr, int dir)
 
 /***************************************************************************/
 
+__attribute__((used))
 int _write_r(struct _reent *r, int file, char * ptr, int len)
 {
   (void)r;
@@ -117,6 +120,7 @@ int _write_r(struct _reent *r, int file, char * ptr, int len)
 
 /***************************************************************************/
 
+__attribute__((used))
 int _close_r(struct _reent *r, int file)
 {
   (void)r;
@@ -127,6 +131,7 @@ int _close_r(struct _reent *r, int file)
 
 /***************************************************************************/
 
+__attribute__((used))
 caddr_t _sbrk_r(struct _reent *r, int incr)
 {
 #if CH_CFG_USE_MEMCORE
@@ -149,6 +154,7 @@ caddr_t _sbrk_r(struct _reent *r, int incr)
 
 /***************************************************************************/
 
+__attribute__((used))
 int _fstat_r(struct _reent *r, int file, struct stat * st)
 {
   (void)r;
@@ -161,6 +167,7 @@ int _fstat_r(struct _reent *r, int file, struct stat * st)
 
 /***************************************************************************/
 
+__attribute__((used))
 int _isatty_r(struct _reent *r, int fd)
 {
   (void)r;
diff --git a/readme.txt b/readme.txt
index ed2570413..7450fcc6e 100644
--- a/readme.txt
+++ b/readme.txt
@@ -147,6 +147,8 @@
 - RT:  Merged RT4.
 - NIL: Merged NIL2.
 - NIL: Added STM32F7 demo.
+- VAR: Fixed GCC garbage collector discards code in syscalls.c (bug #789)
+       (backported to 16.1.6, 3.0.6).
 - HAL: Fixed Makefile dependencies not generated for .S files (bug #787)
        (backported to 16.1.6, 3.0.6).
 - HAL: Fixed OTGv1 driver not functional on STM32L4 (bug #786)(backported