martinayotte wrote:Althouth it seems that OpenOCD support both SWD and SWIM (if my readings are not wrong), it seems that SWIM is not as much documented as SWD, and it also only backed only my STM, no other ARMs are using it. Am I right ?
You're right, as far as I know SWIM is a proprietary STMicro protocol not an ARM standard. SWD is an ARM standard, which means unlike JTAG it has quite a lot of ARM-specific assumptions about the debug port layout baked into it (ie the layer above the on-the-wire signalling, implemented in openocd/whatever).
So, sadly, there's no easy way to rewire a JTAG port as SWD. Even if Espressif modified their silicon there's not really an easy way to have an Xtensa debug port look like an SWD-compatible ARMv5 debug port. They could maybe do 'reduced pin count JTAG' though, which is yet another two wire protocol!
For my 2c, I've worked a lot with SWD and JTAG and although I prefer SWD on ARM, you get used to the extra wires. Besides, with a gdb stub on xtensa you can have 'zero-wire' debugging!