Note that the patchset has only really been tested with RT_PREEMPT or otherwise standard user mode usage.
In particular, there are some patches that change locks and callbacks in ways that I don't think are entirely compatible with RTAI / Xenomai; there have previously been reported problems using those with this patchset. As I was neither the author of those patches nor do I use Xenomai (or EoE) myself, I don't really know what needs to be done to resolve the issues (except just dropping them and possibly breaking the scenario they were originally authored to fix); additionally, I don't have much time at the moment to work on EtherCAT. I welcome assistance in correcting this situation. :) As far as I understand, ec_master_send/receive are only ever supposed to be invoked on one thread at a time; when you're using the userspace library this is enforced by a Linux lock in the corresponding ioctl, but this doesn't apply or is insufficient when using a kernel-mode application or RTAI/Xenomai. In those, you need to register callbacks and use your own appropriate locking mechanism to ensure that the send/receive are not called concurrently. In particular note that both the send callback and the receive callback are permitted to do nothing if called in a context where they can't wait on a lock but something else is concurrently busy doing the same thing. So if you're calling send/receive from an interrupt thread, you will need to keep track of this and force the EoE thread callback to block until the interrupt is done, and also to make the interrupt thread avoid send/receive without blocking if the EoE thread is already in the middle of it. Alternately you could probably make the interrupt handler responsible to do both of these things and have the EoE callbacks always do nothing, which might be better for your application performance. (Though like I said, I haven't looked at the code much in this area so take these suggestions with a grain of salt; I could have something incorrect.) From: etherlab-dev [mailto:etherlab-dev-boun...@etherlab.org] On Behalf Of Geller, Nir Sent: Wednesday, 18 January 2017 23:38 To: etherlab-dev@etherlab.org; Slutsker, Rasty <rasty.sluts...@servotronix.com> Subject: [etherlab-dev] EoE in OP mode Hi, I recently upgraded ethercat master to Gavin Patchset 20160804, adding to that, patch 0061. EoE seems to be working fine while the master is idle, with heavy SDO traffic in parallel. When the master is active our realtime application invokes ecrt_master_receive(master); and ecrt_master_send(master); from interrupt context, and NOT from ec_master_operation_thread() thread context. The problem comes up when the master is active. Just as I issue ifconfig eoe0a1 up I get a bunch of UNMATCHED DATAGRAMS in the kernel log, and the master is released. [ 73.324525] EtherCAT DEBUG 0: UNMATCHED datagram: [ 73.324528] EtherCAT DEBUG: 0D 83 01 00 10 09 08 80 00 00 68 5A 4A 84 9C 9B [ 73.324539] EtherCAT DEBUG: 84 11 01 00 [ 73.324544] EtherCAT DEBUG 0: UNMATCHED datagram: [ 73.324547] EtherCAT DEBUG: 04 84 01 00 90 09 08 80 00 00 B0 3D 4C 84 9C 9B [ 73.324557] EtherCAT DEBUG: 84 11 01 00 [ 73.324562] EtherCAT DEBUG 0: UNMATCHED datagram: [ 73.324565] EtherCAT DEBUG: 0C 85 00 00 00 00 10 80 00 00 00 00 70 FF FF FF [ 73.324575] EtherCAT DEBUG: 50 52 70 FF FF FF 00 00 31 00 03 00 [ 73.324584] EtherCAT DEBUG 0: UNMATCHED datagram: [ 73.324587] EtherCAT DEBUG: 07 86 01 00 30 01 02 00 00 00 08 00 01 00 [ 73.324838] EtherCAT 0: fsm->slaves_responding[fsm->dev_idx]=1 [ 73.324843] EtherCAT 0: 0 slave(s) responding on main device. [ 73.324846] EtherCAT 0: datagram->working_counter=0 <------------------------- In wireshark capture WC is 1 !!!! [ 73.324850] EtherCAT 0: datagram->state=4 [ 73.324853] EtherCAT 0: datagram->device_index=0 [ 73.324856] EtherCAT 0: datagram->device_origin=0 [ 73.324860] EtherCAT 0: datagram->index=134 [ 73.324863] EtherCAT 0: datagram->type=7 [ 73.324866] EtherCAT DEBUG 0: Rescanning the bus This happens due to a timeout. When the EoE thread invokes master->receive_cb(master->cb_data); which leads to invoke of ecrt_master_receive(master); it somehow messes up master->devices[EC_DEVICE_MAIN].cycles_poll which leads to a negative time delta in the calculation master->devices[EC_DEVICE_MAIN].cycles_poll - datagram->cycles_sent. Attempting to bypass that in the EoE thread, I commented out master->receive_cb(master->cb_data); and master->send_cb(master->cb_data); and once I invoke ifconfig eoe0a1 up I get an explosion of [ 123.529911] EtherCAT WARNING 0-main-0: Failed to receive mbox check datagram for eoe0a1. [ 123.529918] EtherCAT WARNING 0-main-0: Failed to receive mbox check datagram for eoe0a1. [ 123.529925] EtherCAT WARNING 0-main-0: Failed to receive mbox check datagram for eoe0a1. [ 123.529932] EtherCAT WARNING 0-main-0: Failed to receive mbox check datagram for eoe0a1. If I comment out only master->receive_cb(master->cb_data); I get no errors in dmesg, but then of course, EoE is not functional, and EoE thread starts gathering more and more CPU usage. I understand that an invoke of master->send_cb(master->cb_data); leads to ec_master_internal_send_cb --> ecrt_master_send_ext(master); which pulls datagrams from master->ext_datagram_queue and pushes them forward with ec_master_queue_datagram(), and then invokes ecrt_master_send(master); which will lead to a collision with ecrt_master_send() in the interrupt context. So instead of invoking master->send_cb(master->cb_data); i tried only to pass datagrams from master->ext_datagram_queue, but it caused a kernel panic. So, if I want EoE to work when the master is active, how should I pass datagrams from EoE thread to the master? Should I change the ethernet.c state machine? Thanks a lot, Nir.
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