PROCESSOR-SDK-AM64X: ethtool set frame preemption and mac verify failed using TI SDK

Matt Tsai52

Tool/software:

Following the sequence of command execution in this page by Pekka: AM6422: eth0 set iet-frame-preemption fail

root@am64xx-evm:~# ip link set dev eth0 down
root@am64xx-evm:~# ethtool -L eth0 tx 2
root@am64xx-evm:~# ethtool --set-priv-flags eth0 p0-rx-ptype-rrobin off
root@am64xx-evm:~# ethtool --set-priv-flags eth0 iet-frame-preemption on
netlink error: bit name not found (offset 48)
netlink error: Operation not supported
root@am64xx-evm:~# ethtool --set-priv-flags eth0 iet-mac-verify on
netlink error: bit name not found (offset 48)
netlink error: Operation not supported

The TI software version:

root@am64xx-evm:~# uname -a
Linux am64xx-evm 6.6.58-ti-01497-ga7758da17c28-dirty #1 SMP PREEMPT Wed Nov 27 13:23:15 UTC 2024 aarch64 GNU/Linux

How to resolve this?

Thank you!

3 months ago

0 Matt Tsai52 3 months ago

Intellectual 935 points

Hi,

Any updates on this? Thank you!

0 Pekka Varis 3 months ago in reply to Matt Tsai52

TI__Mastermind 27050 points

Matt Tsai52 said:
Following the sequence of command execution in this page by Pekka: AM6422: eth0 set iet-frame-preemption fail

These instructions are for SDK from August 2021. You are running a much more recent SDK and Linux kernel, I think from this year. Look at the instructions in the version you re using. https://software-dl.ti.com/processor-sdk-linux-rt/esd/AM64X/latest/exports/docs/linux/Foundational_Components/Kernel/Kernel_Drivers/Network/CPSW-IET.html . Generally we upstream features, and in this process the exact commands might change. It is probably the case here.

Also looks like you running a non-RT kernel. The worst case latency benefit of IET/preemption is in the microseconds range, Linux scheduling worst case behaviour without using the RT config will be 100-1000x worse than anything at Ethernet level.

Pekka

0 Matt Tsai52 3 months ago in reply to Pekka Varis

Intellectual 935 points

Thank you, Pekka.
Here are my results of running the iperf3 sender/receiver example following the instruction. They look reasonable:
On the sender:
root@am64xx-evm:~/iet# ethtool -I --show-mm eth1
MAC Merge layer state for eth1:
pMAC enabled: on
TX enabled: on
TX active: on
TX minimum fragment size: 124
RX minimum fragment size: 124
Verify enabled: on
Verify time: 10
Max verify time: 128
Verification status: SUCCEEDED
Statistics:
MACMergeFrameAssErrorCount: 0
MACMergeFrameSmdErrorCount: 0
MACMergeFrameAssOkCount: 0
MACMergeFragCountRx: 0
MACMergeFragCountTx: 87083
MACMergeHoldCount: 0

On the receiver:
root@am64xx-evm:~/iet# ethtool -I --show-mm eth0
MAC Merge layer state for eth0:
pMAC enabled: on
TX enabled: on
TX active: off
TX minimum fragment size: 124
RX minimum fragment size: 124
Verify enabled: on
Verify time: 10
Max verify time: 128
Verification status: FAILED
Statistics:
MACMergeFrameAssErrorCount: 0
MACMergeFrameSmdErrorCount: 0
MACMergeFrameAssOkCount: 77231
MACMergeFragCountRx: 87083
MACMergeFragCountTx: 0
MACMergeHoldCount: 0

Some follow-up questions:
1. Will TSN features work on a non-RT Linux kernel? Is RT configuration required for TSN features?
2. Is an AM64x EVM RT Linux image available so that we can try TSN features?

Thank you for your help!

0 Pekka Varis 3 months ago in reply to Matt Tsai52

TI__Mastermind 27050 points

Matt Tsai52 said:
1. Will TSN features work on a non-RT Linux kernel? Is RT configuration required for TSN features?

Yes. TSN ensures Ethernet level, so up to layer 2 or 2.5 (VLANs) is deterministic. Ethernet does not care if there is an operating system (or not) on top and how real-time it is. My point is with non-RT Linux your SW will have non-determinism at the level of milliseconds, which very likely defeats the purpose of trying ensure sub microsecond determinism at the communication level.

Matt Tsai52 said:
2. Is an AM64x EVM RT Linux image available so that we can try TSN features?

Yes. RT SD card images are available for all Sitara targets, for AM64x specifically:

https://www.ti.com/product/AM6442#software-development search for RT . Direct links here, Yocto based image first, Debian for simpler "apt install" style second:

https://dr-download.ti.com/software-development/software-development-kit-sdk/MD-InmvA50mCw/11.01.05.03/tisdk-default-image-rt-am64xx-evm-11.01.05.03.rootfs.wic.xz

https://dr-download.ti.com/software-development/software-development-kit-sdk/MD-InmvA50mCw/11.01.05.03/tisdk-debian-trixie-rt-am64xx-evm-11.01-Armbian-25.08.img

Pekka

0 Matt Tsai52 3 months ago in reply to Pekka Varis

Intellectual 935 points

Thank you for the explanation!

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PROCESSOR-SDK-AM64X: ethtool set frame preemption and mac verify failed using TI SDK