Ouss4 opened a new pull request #1958:
URL: https://github.com/apache/incubator-nuttx/pull/1958
## Summary
When external RAM and external FLASH are used together we have to make sure
that:
- For drivers, in case of a DMA transfer, the buffer is DMA capable, i.e.
doesn't originate from external RAM. If it does allocate memory from an
internal heap then copy it back.
- When accessing flash, the cache needs to be disabled, as a consequence
any memory access or code execution need to be from internal memory. A
"special" critical section around flash operations is created to make sure that:
- Buffers don't originate from external RAM
- Tasks' stack aren't allocated from external RAM
- `const` variables aren't in .ro.data.
- Code during this sections is in IRAM.
## Impact
Impacts ESP32 when both PSRAM and SPIFLASH are enabled.
## Testing
esp32-core:spiflash with PSRAM enabled and disabled.
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