Fix a signal trampoline bug

git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@3053 42af7a65-404d-4744-a932-0658087f49c3

ReleaseNotes

@@ -1431,3 +1431,26 @@ include:
   * A new configuration to support the mbed.org LPC1768 board (Contributed
     by Dave Marples), and
   * A driver for the Atmel AT45DB161D 4Mbit SPI FLASH part,
+
+nuttx-5.12
+^^^^^^^^^^
+
+This is the 59th release of NuttX.  This is a critical bugfix release.
+
+	* Fixed an important error in the signal trampoline logic.  Essentially,
+	  interrupts are re-enabled while the signal handler executes, but the
+	  logic to re-disable the interrupts before returning from the signal
+	  handler trampoline was missing.  Under certain circumstances, this
+	  can cause stack corruption.  This was discovered by David Hewson on
+	  an ARM9 platform, but since the code has been leveraged, the bug has
+	  been propogated from ARM to Cortex-M3, AVR32, M16C, SH1, ZNEO, eZ80,
+	  Z8, and Z80 -- almost every architecture. The correction has been
+	  incorporated for all architectures but only verified on a few.
+
+Other notable changes in NuttX-5.12:
+
+	* A complete port for the AVR32 (AT91UC3B0256) is incorporated in the
+	  source tree.  Testing of this port is underway now.  This release
+	  was made before verifying this port in order to get the important
+	  bugfix in place.
+	* Other miscellaneous bugfix and enhancements as noted in the ChangeLog.