Thanks for the clarifications. Now I actually understand what the MPU_Config call from the STM32 example does. I was not sure what that was for. I reintroduced the lwip sections (from my first mail9 again with the values from the STM32 linker script and used the MPU_Config call from the STM32 example. It is now not crashing anymore. I still can't receive UDP packets, but at least I am now able to run my polling loop.
Kind Regards Robin Müller On Thu, 28 Jan 2021 at 18:33, Mr. Andrei Chichak <gro...@chichak.ca> wrote: > Good morning, > > I’ve been trying to get ethernet on STM32F7 going using the bsd networking > stack (not going that well, there is a LOT of undocumented knowledge to > straighten out). > > > The STM32x7 ethernet controllers need their descriptors and data areas to > be located on 32-byte boundaries with a combination of cache being turned > off and buffering being turned off. This is a side effect of the STM32x7 > DMA and data caching. > > The examples that ST have for LWiP under FreeRTOS have some issues with > the linker file having overlapping sections and the stack (above the ETH > data areas) being left with no cache and no buffering. The space above the > rx/tx buffers is also less than the stack space minimum specified in the > linker file as well. Some rearranging of the ETH descriptors and data > areas would be prudent. Like push them to the top of SRAM and locate the > stack below. > > To get this all going, they set up the MPU for two overlapping sections, > one being the top 16kB of SRAM and the other the 256B that contain the ETH > descriptors. I believe the MPU regions can be set in increments of 32Bytes, > so setting up the cache and buffering should be do-able without affecting > the stack. > > > > In RTEMS it appears that I have to pull the data and lengths out of some > mbufs (I had to look that up), and push it all into the data areas. Using > LWiP, I think you do similar things, just pulling the data out of the pbuf > chains. > > On the STM forums is an item about how to actually get a working ETH going > on ST processors. There’s all sorts of issues including Cube generating > code for ST’s dev boards that has the incorrect address for the PHY chip. > Take a look at: > https://community.st.com/s/question/0D50X0000BOtfhnSQB/how-to-make-ethernet-and-lwip-working-on-stm32 > > More later, > > Andrei > > > > --------------------- > Andrei Chichak > > Systems Developer > CBF Systems Inc. > 225 College Plaza > 8215 112 Street. > EDMONTON, ALBERTA > T6G 2C8 > CANADA > > Phone: 780-628-2072 > Skype: andrei.chichak > > > > > > > > > > >
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