Mark, issue #2892 mentions using only the lower 2 MB of SPI RAM as a workaround. Where are our allocations placed by the allocator? Does it fill from the middle or end? If not we don't use the upper half yet. A possible workaround for the most apparent issues with this (string assembly) could be to use char buffers instead of std::string. I was thinking about doing that at least for the websocket stream. But if this really is a hardware issue it can affect all objects in SPI RAM, appending to std::string then only triggers this more often. Another workaround could be to run everything on core 0. Regards, Michael Am 30.01.19 um 03:33 schrieb Mark Webb-Johnson:
Michael,
Espressif’s response (and linking to that other issue) sounds like others are seeing this.
Lousy timing (with Chinese New Year next week), so don’t expect anything quick from Espressif. I guess we’ll just have to live with it until they can find a workaround. It sounds like the issue is at the hardware level and a compiler patch will be needed.
Regards, Mark.
On 30 Jan 2019, at 3:07 AM, Michael Balzer <dexter@expeedo.de <mailto:dexter@expeedo.de>> wrote:
→ https://github.com/espressif/esp-idf/issues/3006
Regards, Michael
Am 28.01.19 um 20:46 schrieb Michael Balzer:
To clarify: the bug is most likely not restricted to the case of building a message in a buffer. It can possibly cause corruptions in any RAM section, so can well be responsible for many/most of the unidentified crashes and stack/heap corruptions we're experiencing.
Regards, Michael
Am 28.01.19 um 20:43 schrieb Michael Balzer:
For those not following the github discussion: I'm pretty sure I've nailed the bug down.
I have reproduced the bug in a simple test project and intend to raise an issue with Espressif on this.
https://github.com/openvehicles/Open-Vehicle-Monitoring-System-3/issues/189#...
If you'd like to test this on your module, configure the project to your wifi credentials, then use "make flash". As the test project is small, this normally will not erase your OVMS config partition, but a backup is always recommended.
Regards, Michael
Am 24.01.19 um 21:19 schrieb Michael Balzer:
Everyone please have a look at…
https://github.com/openvehicles/Open-Vehicle-Monitoring-System-3/issues/189#...
Please try to reproduce the bug on your modules.
I'm open for explanations.
I thought this might be some copy-on-write bug with std::string, but the gcc 5.x libstdc++ does no longer use that implementation (wouldn't be C++11 compliant as well). I also tried moving all strings to temporary buffers, but modes 5 & 6 eliminated this explanation as well.
My remaining theories:
* A task writing out of bounds (but only 0-bytes?) * A hardware issue only affecting some modules
A hardware issue only affecting some percentage of ESP32 could explain this as well as the strange heap corruptions that seem to affect some modules especially often.
Regards, Michael
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