Use standard arm-none-eabi toolchain by default.

boards/arm/sam34/arduino-due/README.txt

@@ -391,6 +391,9 @@ Loading Code
 
     C:\Program Files (x86)\Arduino\arduino-1.5.2\hardware\tools\bossac.exe
 
+    On Debian like distribution, BOSSA can be install through repository:
+    sudo apt install bossa-cli
+
   General Procedure
 
     1) Erase the FLASH and put the Due in bootloader mode
@@ -480,6 +483,10 @@ Loading Code
       Set boot flash true
       CPU reset.
 
+    In Linux shell:
+
+      bossac -i --port=ttyACM0 -U false -e -w -v -b nuttx.bin -R
+
   Other useful bossac operations.
 
     a) Write code to FLASH don't change boot mode and don't reset.  This lets
@@ -865,5 +872,5 @@ Configuration sub-directories
   nsh-leds:
     This configuration directory will build the NuttX Shell and enable the user
     LEDS (/dev/userleds). It will also enable the LED example program (leds).
-    Running the leds command will start up an LED daemon which will light up the 
-    L (user), TX, and RX LEDs in a binary sequence. 
+    Running the leds command will start up an LED daemon which will light up the
+    L (user), TX, and RX LEDs in a binary sequence.

boards/arm/sam34/arduino-due/configs/nsh/defconfig

@@ -14,7 +14,6 @@ CONFIG_ARCH_CHIP_ATSAM3X8E=y
 CONFIG_ARCH_CHIP_SAM34=y
 CONFIG_ARCH_CHIP_SAM3X=y
 CONFIG_ARCH_STACKDUMP=y
-CONFIG_ARM_TOOLCHAIN_BUILDROOT_OABI=y
 CONFIG_BOARD_LOOPSPERMSEC=6965
 CONFIG_BUILTIN=y
 CONFIG_FS_PROCFS=y