So you are using FreeRTOS and Cortex-M3 ? I'm 99% sure your interrupt
routine causes problems and I can help you. (I recently faced with very
similar issue).
1. define LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT to 1 (see description
in src/include/lwip/opt.h). This will let you call safely
mem_malloc()/mem_free() functions or other lwip functions which imply
calls to them (such as pbuf_alloc()) from interrupt context.
2. Make sure your sys arch protection implementation does
taskDISABLE_INTERRUPTS/taskENABLE_INTERRUPTS (or portXXX equivalents).
3. Make sure that numerical(!) value of interrupt priority is equal to
or greater than the configMAX_SYSCALL_INTERRUPT_PRIORITY setting in your
FreeRTOSConfig.h. Also be warned that
configMAX_SYSCALL_INTERRUPT_PRIORITY must not be set to 0. Use only
priorities 1 and above.
4. Make sure you defined priorities values correctly. It's easy to
confuse with them in cortex-m3 because there are no standartized way
across different tools/libraries to treat them in one manner.
FreeRTOSConfig.h macro values must be defined as ready shifted: (prio <<
(8 - __NVIC_PRIO_BITS)), where prio is number from 1 to <max priority
level>. But the way you initialize your interrupts may vary. For
example, if you use STM32 CMSIS library, then you must call
NVIC_PriorityGroupConfig(NVIC_PriorityGroup_4) before
vTaskStartScheduler() and in NVIC_Init() structures you must assign
priority as preemtion priority and set subpriority to 0.
5. Make sure you defined configKERNEL_INTERRUPT_PRIORITY to 255 or (255
<< (8 - __NVIC_PRIO_BITS))
If all above requirements are fulfilled then everything must work
correctly. I'm not sure is #1 essential or not. :)
See http://www.freertos.org/RTOS-Cortex-M3-M4.html for details.
Thanks for the answer.
Should have said LWIP 1.4.0
I understand is most likely a memory corruption.
I have checked the sys_arch code against every other example that I
have been able to find and this matches the cortex M3 implementation
in them all, I have found this at least to be very consistent.
The interrupt routine does call the memp to store the received
packets, transmit uses its own circular buffer so doesn't call any of
lwip memory functions.
// We allocate a _pbuf_ chain of _pbufs_ from the pool.
p = pbuf_alloc(/PBUF_RAW/, len, /PBUF_POOL/);
What do you mean by must be configured correctly?
This is the hardest bit to determine as it is not really clearly
defined anywhere.
I have looked at the examples with FreeRTOS and they vary slightly in
the way they do things (Without a comment as to why) so this makes it
hard to determine what is the correct way.
If you have any advice on the correct way to implement I am happy to hear.
As far as I can tell the memory routines are all wrapped in critical
sections and these match the other examples.
PendSV and Systick for freeRTOS are both being set lowest priority,
TCPIP task is being set mid range priority.
Any additional advice appreciated.
Regards
Barry Andrews
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