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PendSV is the deferred half of the Cortex-M context-switch path: a higher-priority ISR that wakes a task sets PendSV pending and returns, and PendSV then performs the register save/restore. This pattern is only safe when PendSV runs at the lowest priority - otherwise a peripheral ISR can preempt the context switch mid-update and corrupt thread state. The previous write of DEFPRIORITY32 to NVIC_SYSH12_15_PRIORITY in up_irqinitialize() leaves PendSV at NVIC_SYSH_PRIORITY_DEFAULT (0x80), the same priority as peripheral IRQs. Read-modify-write the SHPR3 to lower only the PendSV byte to NVIC_SYSH_PRIORITY_MIN. This is the canonical ARM Cortex-M priority arrangement and it matches e.g. this reference: https://nuttx.apache.org/docs/latest/guides/zerolatencyinterrupts.html (although worked with a three-bit priority system) This patch hardens up_irqinitialize against future peripheral-IRQ prioritisation. Signed-off-by: Daniel Fanache <dan@rts.ro> |
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| dummy | ||
| fs | ||
| graphics | ||
| include | ||
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| mm | ||
| net | ||
| openamp | ||
| pass1 | ||
| sched | ||
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| tools | ||
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| AUTHORS | ||
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| CONTRIBUTING.md | ||
| INVIOLABLES.md | ||
| Kconfig | ||
| LICENSE | ||
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| README.md | ||
| ReleaseNotes | ||
Apache NuttX is a real-time operating system (RTOS) with an emphasis on standards compliance and small footprint. Scalable from 8-bit to 64-bit microcontroller environments, the primary governing standards in NuttX are POSIX and ANSI standards. Additional standard APIs from Unix and other common RTOSs (such as VxWorks) are adopted for functionality not available under these standards, or for functionality that is not appropriate for deeply-embedded environments (such as fork()).
For brevity, many parts of the documentation will refer to Apache NuttX as simply NuttX.
Getting Started
First time on NuttX? Read the Getting Started guide! If you don't have a board available, NuttX has its own simulator that you can run on terminal.
Documentation
You can find the current NuttX documentation on the Documentation Page.
Alternatively, you can build the documentation yourself by following the Documentation Build Instructions.
The old NuttX documentation is still available in the Apache wiki.
Supported Boards
NuttX supports a wide variety of platforms. See the full list on the Supported Platforms page.
Contributing
If you wish to contribute to the NuttX project, read the Contributing guidelines for information on Git usage, coding standard, workflow and the NuttX principles.
License
The code in this repository is under either the Apache 2 license, or a license compatible with the Apache 2 license. See the License Page for more information.