Booting bao from a modified zcu104 on kv260

[sarayyjaan]

On KV260, QSPI boot firmware reaches U-Boot at EL2, but go enters Bao at EL1. ZCU104 demos rely on a custom BOOT.BIN from soc-prebuilt-firmware. Is there a known KV260 bootfw/ATF configuration that preserves EL2 for go, or is flashing a custom Kria QSPI boot firmware required?

[josecm]

Hello @sarayyjaan. This is a known issue with the Xilinx Ultrascale+ baords. You have two possible solutions:

1. Patch U-boot so that it does not jump to EL1 on the go command. This is what we do now in the demos (see https://github.com/bao-project/bao-demos/blob/master/platforms/zcu104/u-boot.patch)
2. Create a bao image using mkimage and use a specific bootm sequence. This is what we done in the past demos (see https://github.com/bao-project/bao-demos/tree/e06a96d4b7787dddce802c0169a6cbd4a18b612f/platforms/zcu104).

Hope this helps

PS: If you are using the KV260, we'd be very grateful if you could contribute back that platform.

[sarayyjaan]

Hello Jose,

Thanks, I was able to get it such that I could load a bao image using alternative methods like creating a uimg file and using fatload, loadm commands instead. I would definitely be willing to contribute back.

However, I am currently running into issues with running ethernet on the kv260 with the bao hypervisor and wanted to ask what are the necessary files required for the ethernet connection for the zcu102/104 as that could be informative for the kv260 board. I'm currently running into issues with the RX path on the kria.

Sara

[Diogo21Costa]

Hello @sarayyjaan,

Hi Sara,
I’ve now added a fully working (wip) demo for the Kria KR260, so this path is working end-to-end on my side.

The main Ethernet-related change I had to make was switching from GEM3 to GEM1. On KR260, the PS Ethernet ports are Ethernet0/GEM0 on J10D (SGMII) and Ethernet1/GEM1 on J10C (RGMII), while the higher-numbered Ethernet ports are on the PL side, so using GEM3 for the PS RJ45 path is the wrong mapping.

In practice, that meant updating the guest DT and Bao configuration together:

• changing the MAC base from the GEM3 node to the GEM1 node,
• updating the corresponding interrupt mapping,
• changing the PHY association,
• and using the matching SMMU master/stream ID for the selected GEM instance (as Jose stated).

One thing that helped a lot was detecting the PHY address directly instead of guessing it from the DTS. I did that from U-Boot using the MII commands: select the active MII device, then read PHY ID registers 2 and 3 across the candidate MDIO addresses. Addresses with no PHY typically return FFFF, while a real PHY returns valid ID words. In my case, address 0x8 responded with valid IDs, so the DTS had to use phy@8 instead of the previous address I was trying.

So, in short, for the Kria Ethernet bring-up the key fix was: use the correct PS GEM instance first. On KR260 that was GEM1 for the RGMII PS port, and once that was aligned, the remaining DT/PHY changes became much easier to sort out.

Let me know if you need further support on the kv260.