CMSIS-Core (M) component is maintained with its own versioning that gets offically updated upon releases of the CMSIS Software Pack.

The table below provides information about the changes delivered with specific versions of CMSIS-Core (M).

Version	Description
V6.0.0	Core(M) and Core(A) joined into single Core component Core header files reworked, aligned with Cortex-M Technical Reference Manuals (TRMs). See Breaking changes in CMSIS-Core v6 header files for details, and GitHub issue #122. Previously deprecated features removed Dropped support for Arm Compiler 5
V5.6.0	Added: Arm Cortex-M85 cpu support Added: Arm China Star-MC1 cpu support Updated: system_ARMCM55.c
V5.5.0	Updated GCC LinkerDescription, GCC Assembler startup Added ARMv8-M Stack Sealing (to linker, startup) for toolchain ARM, GCC Changed C-Startup to default Startup. Updated Armv8-M Assembler startup to use GAS syntax Note: Updating existing projects may need manual user interaction!
V5.4.0	Added: Cortex-M55 cpu support Enhanced: MVE support for Armv8.1-MML Fixed: Device config define checks Added: Cache Functions (Level-1) for Armv7-M and later
V5.3.0	Added: Provisions for compiler-independent C startup code.
V5.2.1	Fixed: Compilation issue in cmsis_armclang_ltm.h introduced in 5.2.0
V5.2.0	Added: Cortex-M35P support. Added: Cortex-M1 support. Added: Armv8.1 architecture support. Added: __RESTRICT and __STATIC_FORCEINLINE compiler control macros.
V5.1.2	Removed using get/set built-ins FPSCR in GCC >= 7.2 due to shortcomings. Added __NO_RETURN to __NVIC_SystemReset() to silence compiler warnings. Added support for Cortex-M1 (beta). Removed usage of register keyword. Added defines for EXC_RETURN, FNC_RETURN and integrity signature values. Enhanced MPUv7 API with defines for memory access attributes.
V5.1.1	Aligned MSPLIM and PSPLIM access functions along supported compilers.
V5.1.0	Added MPU Functions for ARMv8-M for Cortex-M23/M33. Moved __SSAT and __USAT intrinsics to CMSIS-Core. Aligned __REV, __REV16 and __REVSH intrinsics along supported compilers.
V5.0.2	Added macros __UNALIGNED_UINT16_READ, __UNALIGNED_UINT16_WRITE. Added macros __UNALIGNED_UINT32_READ, __UNALIGNED_UINT32_WRITE. Deprecated macro __UNALIGNED_UINT32. Changed Version Control macros to be core agnostic. Added MPU Functions for Armv6-M/v7-M for Cortex-M0+/M3/M4/M7.
V5.0.1	Added: macro __PACKED_STRUCT. Added: uVisor support.
V5.00	Added: Cortex-M23, Cortex-M33 support. Added: macro __SAU_PRESENT with __SAU_REGION_PRESENT. Replaced: macro __SAU_PRESENT with __SAU_REGION_PRESENT. Reworked: SAU register and functions. Added: macro __ALIGNED. Updated: function SCB_EnableICache. Added: cmsis_compiler.h with compiler specific CMSIS macros, functions, instructions. Added: macro __PACKED. Updated: compiler specific include files. Updated: core dependant include files. Removed: deprecated files core_cmfunc.h, core_cminstr.h, core_cmsimd.h.
V5.00 Beta 6	Added: SCB_CFSR register bit definitions. Added: function NVIC_GetEnableIRQ. Updated: core instruction macros __NOP, __WFI, __WFE, __SEV for toolchain GCC.
V5.00 Beta 5	Moved: DSP libraries from CMSIS/DSP/Lib to CMSIS/Lib. Added: DSP libraries build projects to CMSIS pack.
V5.00 Beta 4	Updated: ARMv8M device files. Corrected: ARMv8MBL interrupts. Reworked: NVIC functions.
V5.00 Beta 2	Changed: ARMv8M SAU regions to 8. Changed: moved function TZ_SAU_Setup to file partition_<device>.h. Changed: license under Apache-2.0. Added: check if macro is defined before use. Corrected: function SCB_DisableDCache. Corrected: macros _VAL2FLD, _FLD2VAL. Added: NVIC function virtualization with macros CMSIS_NVIC_VIRTUAL and CMSIS_VECTAB_VIRTUAL.
V5.00 Beta 1	Renamed: cmsis_armcc_V6.h to cmsis_armclang.h. Renamed: core_*.h to lower case. Added: function SCB_GetFPUType to all CMSIS cores. Added: ARMv8-M support.
V4.30	Corrected: DoxyGen function parameter comments. Corrected: IAR toolchain: removed for NVIC_SystemReset the attribute(noreturn). Corrected: GCC toolchain: suppressed irrelevant compiler warnings. Added: Support files for Arm Compiler v6 (cmsis_armcc_v6.h).
V4.20	Corrected: MISRA-C:2004 violations. Corrected: predefined macro for TI CCS Compiler. Corrected: function __SHADD16 in arm_math.h. Updated: cache functions for Cortex-M7. Added: macros _VAL2FLD, _FLD2VAL to core_*.h. Updated: functions __QASX, __QSAX, __SHASX, __SHSAX. Corrected: potential bug in function __SHADD16.
V4.10	Corrected: MISRA-C:2004 violations. Corrected: intrinsic functions __DSB, __DMB, __ISB. Corrected: register definitions for ITCMCR register. Corrected: register definitions for CONTROL_Type register. Added: functions SCB_GetFPUType, SCB_InvalidateDCache_by_Addr to core_cm7.h. Added: register definitions for APSR_Type, IPSR_Type, xPSR_Type register. Added: __set_BASEPRI_MAX function to core_cmFunc.h. Added: intrinsic functions __RBIT, __CLZ for Cortex-M0/CortexM0+.
V4.00	Added: Cortex-M7 support. Added: intrinsic functions for __RRX, __LDRBT, __LDRHT, __LDRT, __STRBT, __STRHT, and __STRT
V3.40	Corrected: C++ include guard settings.
V3.30	Added: COSMIC tool chain support. Corrected: GCC __SMLALDX instruction intrinsic for Cortex-M4. Corrected: GCC __SMLALD instruction intrinsic for Cortex-M4. Corrected: GCC/CLang warnings.
V3.20	Added: __BKPT instruction intrinsic. Added: __SMMLA instruction intrinsic for Cortex-M4. Corrected: ITM_SendChar. Corrected: __enable_irq, __disable_irq and inline assembly for GCC Compiler. Corrected: NVIC_GetPriority and VTOR_TBLOFF for Cortex-M0/M0+, SC000. Corrected: rework of in-line assembly functions to remove potential compiler warnings.
V3.01	Added support for Cortex-M0+ processor.
V3.00	Added support for GNU GCC ARM Embedded Compiler. Added function __ROR. Added Register Mapping for TPIU, DWT. Added support for SC000 and SC300 processors. Corrected ITM_SendChar function. Corrected the functions __STREXB, __STREXH, __STREXW for the GNU GCC compiler section. Documentation restructured.
V2.10	Updated documentation. Updated CMSIS core include files. Changed CMSIS/Device folder structure. Added support for Cortex-M0, Cortex-M4 w/o FPU to CMSIS DSP library. Reworked CMSIS DSP library examples.
V2.00	Added support for Cortex-M4 processor.
V1.30	Reworked Startup Concept. Added additional Debug Functionality. Changed folder structure. Added doxygen comments. Added definitions for bit.
V1.01	Added support for Cortex-M0 processor.
V1.01	Added intrinsic functions for __LDREXB, __LDREXH, __LDREXW, __STREXB, __STREXH, __STREXW, and __CLREX
V1.00	Initial Release for Cortex-M3 processor.

Breaking changes in CMSIS-Core v6 header files

CMSIS-Core Standard Files in CMSIS-Core v6.0.0 have received a number of changes that are incompatible with CMSIS-Core v5.6.0.

In summary, following types of incompatible changes are present:

struct member is renamed in an existing structure (e.g. NVIC->PR -> NVIC->IPR)
struct name is changed (e.g. CoreDebug_Type -> DCB_Type)
define name is changed (e.g. CoreDebug_DEMCR_TRCENA_Msk -> DCB_DEMCR_TRCENA_Msk)

GitHub issue #122 discusses how to resolve such incompatibilities.

Below is detailed information about the changes relevant for each Cortex-M core.

Cortex-M0, Cortex-M0+, Cortex-M1:

struct NVIC_Type
- member IP renamed to IPR
struct SCB_Type
- member SHP renamed to SHPR

Cortex-M3, Cortex-M4:

struct NVIC_Type
- member IP renamed to IPR
struct SCB_Type
- member SHP renamed to SHPR
- member PFR renamed to ID_PFR
- member PFR renamed to ID_PFR
- member DFR renamed to ID_PFR
- member ADR renamed to ID_AFR
- member MMFR renamed to ID_MMFR
- member ISAR renamed to ID_ISAR
- member STIR added
struct ITM_Type:
- members PIDx and CIDx removed
define names for ITM_TCR_* changed
define names for ITM_LSR_* changed
struct TPI_Type renamed to TPIU_Type
define names for TPI_* renamed to TPIU_*
define names for FPU_MVFR0/1_* changed (Cortex-M4)
struct CoreDebug_Type renamed to DCB_Type
defines for CoreDebug_* renamed to DCB_*

Cortex-M7:

struct NVIC_Type
- member IP renamed to IPR
struct SCB_Type
- member ID_MFR renamed to ID_MMFR
struct ITM_Type:
- members PIDx and CIDx removed
define names for ITM_TCR_* changed
define names for ITM_LSR_* changed
struct TPI_Type renamed to TPIU_Type
define names for TPI_* renamed to TPIU_*
define names for FPU_MVFR0/1_* changed
struct CoreDebug_Type renamed to DCB_Type
defines for CoreDebug_* renamed to DCB_*

Cortex-M23:

struct DWT_Type
- member RESERVED0[6] replaced by CYCCNT, CPICNT, EXCCNT, SLEEPCNT, LSUCNT, FOLDCNT
- other RESERVED members mainly removed
struct TPI_Type renamed to TPIU_Type
define names for TPI_* renamed to TPIU_*
struct CoreDebug_Type removed (struct DCB_Type already existed)
defines CoreDebug_ removed (defines DCB_ already existed)

Cortex-M33:

struct ITM_Type:
- members LAR, LSR removed
- members PIDx and CIDx removed
struct TPI_Type renamed to TPIU_Type
define names for TPI_* renamed to TPIU_*
define names for FPU_MVFR0/1_* changed
struct CoreDebug_Type removed (struct DCB_Type already existed)
defines CoreDebug_ removed (defines DCB_ already existed)

Cortex-M55, Cortex-M85:

struct ITM_Type:
- members LAR, LSR removed
- members PIDx and CIDx removed
struct DWT_Type:
- members PIDx and CIDx removed
struct EWIC_Type
- all members renamed
define names EWIC_* changed
struct TPI_Type renamed to TPIU_Type
- members LAR, LSR replaced
define names for TPI_* renamed to TPIU_*
struct PMU_Type
- members PIDx and CIDx removed
struct CoreDebug_Type removed (struct DCB_Type already existed)
defines CoreDebug_ removed (defines DCB_ already existed)
struct DIB_Type
- members DLAR, DLSR removed (replaced by RESERVED0[2])
defines for DIB_DLAR_* and DIB_DLSR_* removed