New Features
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* Re-tied the MALLOC_LOCK and MALLOC_UNLOCK to newlib's multithread configuration for newlib-nano.
Important bugs fixed in 5 update 2 release
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* Fixed code-size regression for Cortex-M0 compared to 4.9 when compiling with -Os
* Fix multilib used for armv8-m.main+dsp
* Fix use of --gc-sections when building for ARMv8-M with Security Extensions
* Fix memcpy used for newlib-nano for pre ARMv6T2 devices
* Fix alignment of .data in ldscripts in samples
* Fix semihosting for ARMv7-A and ARMv7-R
Known Changes and Issues
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* Thumb1 code size regression due to new register allocation:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61578
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59535
*A workaround is to disable it by option -mno-lra*.
* The use of 64-bit atomic operations for ARMv8-M Mainline is not supported.