# Frequently Asked Build Questions This page covers questions about building QMK. If you haven't yet done so, you should read the [Build Environment Setup](getting_started_build_tools.md) and [Make Instructions](getting_started_make_guide.md) guides. ## Can't Program on Linux You will need proper permissions to operate a device. For Linux users, see the instructions regarding `udev` rules, below. If you have issues with `udev`, a work-around is to use the `sudo` command. If you are not familiar with this command, check its manual with `man sudo` or [see this webpage](https://linux.die.net/man/8/sudo). An example of using `sudo`, when your controller is ATMega32u4: $ sudo dfu-programmer atmega32u4 erase --force $ sudo dfu-programmer atmega32u4 flash your.hex $ sudo dfu-programmer atmega32u4 reset or just: $ sudo make ::dfu Note that running `make` with `sudo` is generally *not* a good idea, and you should use one of the former methods, if possible. ## Linux `udev` Rules On Linux, you'll need proper privileges to access the MCU. You can either use `sudo` when flashing firmware, or place these files in `/etc/udev/rules.d/`. **/etc/udev/rules.d/50-atmel-dfu.rules:** ``` # Atmel ATMega32U4 SUBSYSTEMS=="usb", ATTRS{idVendor}=="03eb", ATTRS{idProduct}=="2ff4", MODE:="0666" # Atmel USBKEY AT90USB1287 SUBSYSTEMS=="usb", ATTRS{idVendor}=="03eb", ATTRS{idProduct}=="2ffb", MODE:="0666" # Atmel ATMega32U2 SUBSYSTEMS=="usb", ATTRS{idVendor}=="03eb", ATTRS{idProduct}=="2ff0", MODE:="0666" ``` **/etc/udev/rules.d/52-tmk-keyboard.rules:** ``` # tmk keyboard products https://github.com/tmk/tmk_keyboard SUBSYSTEMS=="usb", ATTRS{idVendor}=="feed", MODE:="0666" ``` ## WINAVR is Obsolete It is no longer recommended and may cause some problem. See [TMK Issue #99](https://github.com/tmk/tmk_keyboard/issues/99). ## USB VID and PID You can use any ID you want with editing `config.h`. Using any presumably unused ID will be no problem in fact except for very low chance of collision with other product. Most boards in QMK use `0xFEED` as the vendor ID. You should look through other keyboards to make sure you pick a unique Product ID. Also see this. https://github.com/tmk/tmk_keyboard/issues/150 You can buy a really unique VID:PID here. I don't think you need this for personal use. - http://www.obdev.at/products/vusb/license.html - http://www.mcselec.com/index.php?page=shop.product_details&flypage=shop.flypage&product_id=92&option=com_phpshop&Itemid=1 ## Cortex: `cstddef: No such file or directory` GCC 4.8 of Ubuntu 14.04 had this problem and had to update to 4.9 with this PPA. https://launchpad.net/~terry.guo/+archive/ubuntu/gcc-arm-embedded https://github.com/tmk/tmk_keyboard/issues/212 https://github.com/tmk/tmk_keyboard/wiki/mbed-cortex-porting#compile-error-cstddef https://developer.mbed.org/forum/mbed/topic/5205/ ## `clock_prescale_set` and `clock_div_1` Not Available Your toolchain is too old to support the MCU. For example WinAVR 20100110 doesn't support ATMega32u2. ``` Compiling C: ../../tmk_core/protocol/lufa/lufa.c avr-gcc -c -mmcu=atmega32u2 -gdwarf-2 -DF_CPU=16000000UL -DINTERRUPT_CONTROL_ENDPOINT -DBOOTLOADER_SIZE=4096 -DF_USB=16000000UL -DARCH=ARCH_AVR8 -DUSB_DEVICE_ONLY -DUSE_FLASH_DESCRIPTORS -DUSE_STATIC_OPTIONS="(USB_DEVICE_OPT_FULLSPEED | USB_OPT_REG_ENABLED | USB_OPT_AUTO_PLL)" -DFIXED_CONTROL_ENDPOINT_SIZE=8 -DFIXED_NUM_CONFIGURATIONS=1 -DPROTOCOL_LUFA -DEXTRAKEY_ENABLE -DCONSOLE_ENABLE -DCOMMAND_ENABLE -DVERSION=unknown -Os -funsigned-char -funsigned-bitfields -ffunction-sections -fdata-sections -fno-inline-small-functions -fpack-struct -fshort-enums -fno-strict-aliasing -Wall -Wstrict-prototypes -Wa,-adhlns=obj_alps64/protocol/lufa/lufa.lst -I. -I../../tmk_core -I../../tmk_core/protocol/lufa -I../../tmk_core/protocol/lufa/LUFA-git -I../../tmk_core/common -std=gnu99 -include config.h -MMD -MP -MF .dep/obj_alps64_protocol_lufa_lufa.o.d ../../tmk_core/protocol/lufa/lufa.c -o obj_alps64/protocol/lufa/lufa.o ../../tmk_core/protocol/lufa/lufa.c: In function 'setup_mcu': ../../tmk_core/protocol/lufa/lufa.c:575: warning: implicit declaration of function 'clock_prescale_set' ../../tmk_core/protocol/lufa/lufa.c:575: error: 'clock_div_1' undeclared (first use in this function) ../../tmk_core/protocol/lufa/lufa.c:575: error: (Each undeclared identifier is reported only once ../../tmk_core/protocol/lufa/lufa.c:575: error: for each function it appears in.) make: *** [obj_alps64/protocol/lufa/lufa.o] Error 1 ``` ## BOOTLOADER_SIZE for AVR Note that Teensy2.0++ bootloader size is 2048byte. Some Makefiles may have wrong comment. ``` # Boot Section Size in *bytes* # Teensy halfKay 512 # Teensy++ halfKay 2048 # Atmel DFU loader 4096 (TMK Alt Controller) # LUFA bootloader 4096 # USBaspLoader 2048 OPT_DEFS += -DBOOTLOADER_SIZE=2048 ``` ## `avr-gcc: internal compiler error: Abort trap: 6 (program cc1)` on MacOS This is an issue with updating on brew, causing symlinks that avr-gcc depend on getting mangled. The solution is to remove and reinstall all affected modules. ``` brew rm avr-gcc brew rm dfu-programmer brew rm gcc-arm-none-eabi brew rm avrdude brew install avr-gcc brew install dfu-programmer brew install gcc-arm-none-eabi brew install avrdude ``` 1'>61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315