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Common pitfalls document: Add note that lwip writes to ethernet RX buffers (caching issue!)

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Dirk Ziegelmeier 2017-12-24 13:02:30 +01:00
parent 61e90d9fc0
commit 8f6b876ef9
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doc/doxygen/main_page.h
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@ -164,6 +164,19 @@
* @ref LOCK_TCPIP_CORE() and @ref UNLOCK_TCPIP_CORE().
* These macros cannot be used in an interrupt context!
* Note the OS must correctly handle priority inversion for this.
*
* Cache issues
* ========================================
*
* DMA-capable ethernet hardware and zero-copy RX
* ----------------------------------------------
*
* lwIP changes the content of RECEIVED pbufs in the TCP code path.
* This implies one or more cacheline(s) of the RX pbuf become dirty
* and need to be flushed before the memory is handed over to the
* DMA ethernet hardware for the next telegram to be received.
* See http://lwip.100.n7.nabble.com/in-place-overwriting-of-payload-via-static-quot-tcphdr-quot-pointer-td31434.html
* for a more detailed explanation.
*/
/**