I’m investigating whether ARM Errata ID 838869 (“Store immediate overlapping exception return operation might vector to incorrect interrupt”) affects Cortex-M7 silicon, in addition to the documented Cortex-M4/M4F cores. Here’s what I’ve found so far:
ARM SDEN-1068427 (Cortex-M7 Errata Notice v11.0, May 28 2024) The official ARM Software Developer’s Errata Notice for Cortex-M7 does not list ID 838869 in its summary table. PDF: https://documentation-service.arm.com/static/665dff778ad83c4754308908?token=
STMicroelectronics STM32H7 Errata (ES0445 Rev 5, September 2024) In ST’s device errata sheet, 838869 appears only under the “Arm 32-bit Cortex-M4 core” section, and is not listed under “Cortex-M7 core.” PDF: https://www.st.com/resource/en/errata_sheet/es0445-stm32h7x7errata.pdf
NXP MCUXpresso SDK (release 25.03.00) Despite the above, the MCUXpresso fsl_common_arm.h driver uses:/*! @name ISR exit barrier * @{ * * ARM errata 838869, affects Cortex-M4, Cortex-M4F Store immediate overlapping * exception return operation might vector to incorrect interrupt. * For Cortex-M7, if core speed much faster than peripheral register write speed, * the peripheral interrupt flags may be still set after exiting ISR, this results to * the same error similar with errata 83869. */#if (defined __CORTEX_M) && ((__CORTEX_M == 4U) || (__CORTEX_M == 7U))#define SDK_ISR_EXIT_BARRIER __DSB()#else#define SDK_ISR_EXIT_BARRIER#endifimplying NXP applies a DSB barrier at ISR exit on both M4 and M7 cores. Source: https://github.com/nxp-mcuxpresso/mcuxsdk-core/blob/release/25.03.00/drivers/common/fsl_common_arm.h#L369-L383
fsl_common_arm.h
My questions:
Has ARM observed or documented any Cortex-M7 devices actually affected by errata 838869?
If not, can you confirm that adding __DSB() on M7 is purely a precaution against slow peripheral‐write latency rather than compensating for a core bug?
__DSB()
Are there any unpublished or upcoming M7-specific errata we should be aware of?
Thanks in advance for any clarification or pointers!
No reply for 3 months? That's unusual for a well drafted question like this one.