When SIMPLE_MODE=0 for AXI_WRAPPER, is the header provided as the first data word (or two data words if the timestamp is used) on m_axis_data_tdata? It seemed redundant since it’s provided on m_axis_data_tuser, but the Header is shown in the waveform on Slide 22 of the RFNOC Workshop (Part 2), so I wanted to clarify exactly what the data on m_axis_data_tdata will be. Also, I assume that this same behavior should be mimicked on s_axis_data_tdata when sending a packet out, but again, I wanted to clarify.
Thanks, Jeff ________________________________ From: Jonathon Pendlum <jonathon.pend...@ettus.com> Sent: Wednesday, December 16, 2020 12:05:58 AM To: Hodges, Jeff Cc: usrp-users@lists.ettus.com Subject: Re: [USRP-users] RFNoC passing metadata on the dataplane Hi Jeff, Is there a document describing the CHDR header for 3.15? Looking at the code, there are significant differences between the header format in 3.15 and what’s in the 4.0 spec. I think I understand it from the code, but if there’s a doc with more detail or explanation, that would be useful. The RFNoC3 CHDR header is described in the UHD 3.15 manual: https://files.ettus.com/manual_archive/v3.15.0.0/html/page_rtp.html. There is a bit more detail in these slides: https://kb.ettus.com/images/f/f6/rfnoc3_workshop_slides_202008_part_2.pdf Is there a maximum payload size for a CHDR data packet Technically it is 64k bytes, but due to FIFO sizing in our devices, you should not exceed 7992 bytes / 1998 SC16 samples. Jonathon On Tue, Dec 15, 2020 at 11:18 PM Hodges, Jeff <jeff.hod...@gtri.gatech.edu<mailto:jeff.hod...@gtri.gatech.edu>> wrote: Thanks, Jonathan, that is very helpful. Two questions using SIMPLE_MODE=0 and AXI wrapper: 1. Is there a document describing the CHDR header for 3.15? Looking at the code, there are significant differences between the header format in 3.15 and what’s in the 4.0 spec. I think I understand it from the code, but if there’s a doc with more detail or explanation, that would be useful. 2. Is there a maximum payload size for a CHDR data packet Jeff ________________________________ From: Jonathon Pendlum <jonathon.pend...@ettus.com<mailto:jonathon.pend...@ettus.com>> Sent: Friday, December 11, 2020 4:47:57 PM To: Hodges, Jeff Cc: usrp-users@lists.ettus.com<mailto:usrp-users@lists.ettus.com> Subject: Re: [USRP-users] RFNoC passing metadata on the dataplane Hi Jeff, RFNoC3 / UHD 3.15 does not support metadata. That is a new feature in RFNoC4 / UHD 4.0, so option 2 is not possible. If you want to send out metadata in RFNoC3, I would suggest prepending it to packets you send to AXI wrapper. You can still use SIMPLE_MODE as long as you are producing a packet for every packet consumed. The different input/output packet lengths do not matter as AXI wrapper internally calculates the output packet length and updates the header automatically. Jonathon On Fri, Dec 11, 2020 at 3:48 PM Hodges, Jeff via USRP-users <usrp-users@lists.ettus.com<mailto:usrp-users@lists.ettus.com>> wrote: I meant rfnoc_create_verilog.py https://github.com/EttusResearch/uhd/blob/master/host/utils/rfnoc_blocktool/rfnoc_create_verilog.py jeff ________________________________ From: Hodges, Jeff Sent: Friday, December 11, 2020 3:44:41 PM To: usrp-users@lists.ettus.com<mailto:usrp-users@lists.ettus.com> Subject: RFNoC passing metadata on the dataplane I'd like to pass metadata over the dataplane using the available space in the CHDR header. However, I cannot find an easy way to do this using UHD3.15. I've identified two possible approaches but I'm not sure either will work: (1) Set AXI_Wrapper (Simple_Mode =0) to require user provided CHDR header. It's unclear how to provide the header, and if this can be modified quickly. (2) Expose the AXI-Stream CHDR interface the way UHD4.0 does it: In UHD4.0 the verilog_image_builder.py includes the options to expose HDL interface: o Definition: Which HDL interface to expose o Options: “AXI-Stream CHDR” (axis_chdr), “AXI-Stream Payload Context” (axis_pyld_ctxt), or “AXI-Stream Data” (axis_data) If Option (2) is the recommended, can I just copy the code from verilog_image_builder.py TEMPLATE such as below, or were other changes made to make it incompatible with 3.15? %if config['data']['fpga_iface'] == "axis_pyld_ctxt": assign axis_data_clk = ${config['data']['clk_domain']}_clk; assign axis_data_rst = ${config['data']['clk_domain']}_rst; <%include file="/modules/axis_pyld_ctxt_modules_template.mako"/> Thanks, Jeff _______________________________________________ USRP-users mailing list USRP-users@lists.ettus.com<mailto:USRP-users@lists.ettus.com> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
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