tested right now COMPILING on windows and running in linux: 2.6 gives warning but run, 3.0 does not enumerate.
i've also tryed to run it on windows, but seems like win 7 does not like cdc on USB 3.0 port.... it keeps failing installing driver, i've tryed a lot of them, even "USB Inf Builder".... seems like it see VID and PID "0000" followed by a lot of garbage. Arduino UNO on CDC work fine on USB 2.0 and 3.0 ports. Also programming the ST run fine on usb 3 and 2
2.6 (compiled on windows) runs fine on windows usb 2.0 port (i don't know where is keeps log, so i don't know if give equivalent warning as linux)
3.0 (compiled on windows, no LTO) does NOT run on usb2.0; it give explicit message "usb device did not work correctly" ( in my language, tranlation may vary

)
strange it does NOT give this error on USB3.0 port
all compiling (of all test) has been done on ONE machine, while plug test has been done on the above machine and another machine, a laptop without usb3.0 but still running linux.
i'll try to get my hand on another board and set up the other PC to test that.
meanwhile, using UART + FTDI chip run just fine. i'm loosing bandwith, but i don't care as it was planned to use xbee as communication link... just this puzzle me a lot. I may provide more USB sniff on windows and linux with wireshark, and even try to undertsand the one provided (of chibios3 some post ago) but free time is low and i want to go on the project.
tell me if and how i can provide usefull information
lesto
edit: to run chibios3 on chibistudio i do this:
close eclipse
rename chibios and workspace as chibios2.6 and workspace2.6
dowloaded chibios3
renamed the folder to chibios and place where it should be
open eclipse (workspace folder is created)
copy "C:\ChibiStudio\workspace2.6\.metadata\.plugins\org.eclipse.debug.core" to "C:\ChibiStudio\workspace\.metadata\.plugins\org.eclipse.debug.core" (this will give you external tool "openocd")
import existing project (be sure copy on workspace is NOT flagged)
run openocd
build and upload test USB CDC
from here, i just close eclipse and swap chibios and workspace folder between the two version. a "swap batch" may be easly writte, not tested but i'm pretty sure "hotswap" will create A LOT of problem, just don't do it