I am curious about those points as well. For a Cortex M class of devices, accessing MMRs via the DAP (through JTAG) can be done unobtrusively w.r.t the CPU and the major pain is having absolutely ALL registers, bitfields, comments, etc. created by the manufacturer or someone else.
I work with TM4C/MSP devices from TI and their Eclipse-based IDE has all this (it has other idiosyncracies, but this works well).
Hopefully some of these questions have been resolved in a earlier reply, but if not, please feel free to rephrase until I produce a satisfactory answer for you.
The post I initially responded to was regarding which IDE people use, and being a Forth user I'm trying to avoid any and all flame wars with people who love their editor,SCM, MCU and programming language dearly, however I'll try and answer any questions providing members here understand that I believe the best editor,SCM, MCU and programming language is the one that suits THEM the best, not the one I happen to use
While I'm no expert with Eclipse I have used it when I evaluated such IDE's as Atollic Studio and I could see the attraction, but the fact that I'd need a i7 with 32GB ram to run it in a reasonable time, and given the humongous complexity lurking underneath meant that I lost interest within a couple days.
I have Forth running on TM4C/MSP devices, in fact I have a MSP430 (target) JTAG tethered Forth running *from* a Ti Connected Launchpad (host) which is doing live compilation for the target which means I can (seemingly) write a Forth program and run it interactively on the target MCU even if it only has a couple of hundred bytes of Flash, because the host is sending machine code to the target. At the end of my development the host will produce and flash the completed turnkey application binary to the target via the same JTAG used for the tether. Tell me that's not cool ?
The interactive Forth that *seems* to be running on the target, is actually running on the Host. Hardware speed of the Forth target is about 20 times slower than when it's running the completed binary image produced by the host, however the interactive Forth speed of the target seems normal at 460800 Baud.
If you're interested please see
http://hightechdoc.net/mecrisp-across/_build/html/index.html but be aware it's all beta level, and I'm not the creator, just a user.
Thanks to various (mainly Rust) users I have also made CMSIS-SVD's for TM4C/MSP devices which can then be used for automatic memory mapped Forth Word creation. One sure needs this when using a TM4C because the sheer number of registers and bitfields are just *unbelievable*!
The MSP430 on the other hand is just a cute lil thing, a master of low power and interrupts with the sweetest Assembly Language seen since the MC6800 (imho).