I wanted to share my findings regarding flashing an iotlab-m3 board from OS X 10.11.
The good thing, the 3rd party FTDI driver is not needed anymore. Apple delivered a FTDI kernel extension for some releases already but I didn't find them working until this release. So, when connecting an iotlab-m3 board to your Mac without having the old FTDI driver loaded you should already be able to connect to the /dev/tty.usbserial-xxxxxB device with by executing
`BOARD=iotlab-m3 PORT=/dev/tty.usbserial-xxxxxB make term`
The bad thing, flashing fails as the Apple driver also assigns /dev/tty.usbserial-xxxxxA to the first serial device on the board and openocd can't claim it. I could successfully prevent it from doing so by these steps:
DISCLAIMER: backup first and you do this on your own reliability.
1. `sudo nvram boot-args=kext-dev-mode=1` We will change the kext's Info.plist so the signature will not be valid anymore.
2. Boot into recovery mode by holding cmd + r during start up
3. In recovery mode open a terminal and execute `csrutil disable` to turn off System Integrity Protection.
4. Restart into normal mode an use your editor of choice to edit the file /System/Library/Extensions/AppleUSBFTDI.kext/Contents/Info.plist and comment out the <key> and <dict> entries for "AppleUSBEFTDI-6010-0" with <!-- ... --> See the snip below.
5. Restart into recovery mode again and enable System Integrity Protection again by `csrutil enable`
6. Restart into normal mode and you should only see one remaining /dev/tty.usbserial-xxxB device. Flashing the board should work now.
If somebody found an easier approach, please let me know, else, good luck.
<!--<key>AppleUSBEFTDI-6010-0</key> <dict> <key>CFBundleIdentifier</key> <string>com.apple.driver.AppleUSBFTDI</string> <key>IOClass</key> <string>AppleUSBFTDI</string> <key>IOProviderClass</key> <string>IOUSBHostInterface</string> <key>InputBuffers</key> <integer>8</integer> <key>OutputBuffers</key> <integer>16</integer> <key>bConfigurationValue</key> <integer>1</integer> <key>bInterfaceNumber</key> <integer>0</integer> <key>idProduct</key> <integer>24592</integer> <key>idVendor</key> <integer>1027</integer> </dict>-->