Add VCU128 flavor using internal JTAG chain

[ferchup]

Hi, I am trying to debug on the vcu128 in baremetal and some questions comes up. Why is the JTAG interface accessed via the FMC and not the USB? Is it for OpenOCD reason? If I don't have the FMC XM105 adapter or the HS2 cable, is there any other alternative? Thanks

[paulsc96]

Please consider naming your issues appropriately. If your issue is really a question and the question is "Why does VCU128 use HS2 adapter on XM105 card?", that would be a more helpful title.

The reason why is that there is only one JTAG chain onboard, and that VIO/ILA control and debugging through OpenOCD cannot be supported simultaneously (Vivado and OpenOCD both claim the USB device). However, unlike Genesys2, VCU128 does not have hardware switches, so this presents a usability problem.

We originally had plans to support both the internal chain and HS2 through XM105 for debugging, but had no time to properly implement support for multiple flavors of the same board. For the time being, I will rename this issue to the underlying feature request: "Add VCU128 flavor using internal JTAG chain".

That said, you can just manually change the constraints to map the JTAG DTM to the internal chain, knowing you lose VIO control (there is no avoiding this).