ed5a661da8
At system startup, the NVIC was configured for proper default priority only for the first three IPR registers, even though the loop was executed 13 times - due to a gotcha on what the `NVIC_IRQ_PRIORITY(i)` macro returns. IRQs 12-51 stayed at the reset priority of 0 - highest in the system; so any peripherals issuing those interrupts will shoot through critical sections that rely on BASEPRI = NVIC_SYSH_PRIORITY_DEFAULT (0x80). This can corrupt the TCB ready-to-run list and semaphore wait queues; this is hard to reproduce (e.g. in ostest) because it requires a peripheral ISR to land inside a critical section, but the failure modes range from hangs to wild pointer crashes once it does. In my case I had SPI and I2C peripherals that were issuing IRQs and were preempting scheduler and semaphore list operations, causing corruption. Step the loop by four and bound it with RP23XX_IRQ_NEXTINT so every IPR covering IRQs 0..51 is written once with DEFPRIORITY32. Signed-off-by: Daniel Fanache <dan@rts.ro> |
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| dummy | ||
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| pass1 | ||
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| CONTRIBUTING.md | ||
| INVIOLABLES.md | ||
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| 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.