# Frequently Asked Build Questions
-This page covers questions about building QMK. If you have not yet you should read the [Build Environment Setup](build_environment_setup.md) and [Make Instructions](make_instructions.md) guides.
+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 permission to operate a device. For Linux users see udev rules below. Easy way is to use `sudo` command, if you are not familiar with this command check its manual with `man sudo` or this page on line.
+## 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:
-In short 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 <keyboard>-<keymap>-dfu
-
-But to run `make` with root privilege is not good idea. Use former method if possible.
-
-## WINAVR is obsolete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.
+or just:
-Also see this.
-https://github.com/tmk/tmk_keyboard/issues/150
+ $ sudo make <keyboard>:<keymap>:dfu
-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
+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 need proper privilege to access device file of MCU, you'll have to use `sudo` when flashing firmware. You can circumvent this with placing these files in `/etc/udev/rules.d/`.
+### 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/`. Once added run the following:
+```console
+sudo udevadm control --reload-rules
+sudo udevadm trigger
+```
**/etc/udev/rules.d/50-atmel-dfu.rules:**
```
# tmk keyboard products https://github.com/tmk/tmk_keyboard
SUBSYSTEMS=="usb", ATTRS{idVendor}=="feed", MODE:="0666"
```
+**/etc/udev/rules.d/54-input-club-keyboard.rules:**
+```
+# Input Club keyboard bootloader
+SUBSYSTEMS=="usb", ATTRS{idVendor}=="1c11", MODE:="0666"
+```
-## 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/
+**/etc/udev/rules.d/55-caterina.rules:**
+```
+# ModemManager should ignore the following devices
+ATTRS{idVendor}=="2a03", ENV{ID_MM_DEVICE_IGNORE}="1"
+ATTRS{idVendor}=="2341", ENV{ID_MM_DEVICE_IGNORE}="1"
+```
+**Note:** ModemManager filtering only works when not in strict mode, the following commands can update that settings:
+```console
+sudo sed -i 's/--filter-policy=strict/--filter-policy=default/' /lib/systemd/system/ModemManager.service
+sudo systemctl daemon-reload
+sudo systemctl restart ModemManager
+```
-## '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.
+**/etc/udev/rules.d/56-dfu-util.rules:**
+```
+# stm32duino
+SUBSYSTEMS=="usb", ATTRS{idVendor}=="1eaf", ATTRS{idProduct}=="0003", MODE:="0666"
+# Generic stm32
+SUBSYSTEMS=="usb", ATTRS{idVendor}=="0483", ATTRS{idProduct}=="df11", MODE:="0666"
+```
+**/etc/udev/rules.d/57-bootloadhid.rules:**
```
-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
+# bootloadHID
+SUBSYSTEMS=="usb", ATTRS{idVendor}=="16c0", ATTRS{idProduct}=="05df", MODE:="0666"
```
+### Serial device is not detected in bootloader mode on Linux
+Make sure your kernel has appropriate support for your device. If your device uses USB ACM, such as
+Pro Micro (Atmega32u4), make sure to include `CONFIG_USB_ACM=y`. Other devices may require `USB_SERIAL` and any of its sub options.
+
+## Unknown Device for DFU Bootloader
+
+Issues encountered when flashing keyboards on Windows are most often due to having the wrong drivers installed for the bootloader, or none at all.
+
+Re-running the QMK installation script (`./util/qmk_install.sh` from the `qmk_firmware` directory in MSYS2 or WSL) or reinstalling the QMK Toolbox may fix the issue. Alternatively, you can download and run the [`qmk_driver_installer`](https://github.com/qmk/qmk_driver_installer) package manually.
+
+If that doesn't work, then you may need to download and run Zadig. See [Bootloader Driver Installation with Zadig](driver_installation_zadig.md) for more detailed information.
+
+## 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
## 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
+# Boot Section Size in *bytes*
+# Teensy halfKay 512
+# Teensy++ halfKay 2048
# Atmel DFU loader 4096 (TMK Alt Controller)
-# LUFA bootloader 4096
-# USBaspLoader 2048
+# 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 dfu-util
+brew rm gcc-arm-none-eabi
+brew rm avrdude
+brew install avr-gcc
+brew install dfu-programmer
+brew install dfu-util
+brew install gcc-arm-none-eabi
+brew install avrdude
+```
+
+### avr-gcc 8.1 and LUFA
+
+If you updated your avr-gcc to above 7 you may see errors involving LUFA. For example:
+
+`lib/lufa/LUFA/Drivers/USB/Class/Device/AudioClassDevice.h:380:5: error: 'const' attribute on function returning 'void'`
+
+For now, you need to rollback avr-gcc to 7 in brew.
+
+```
+brew uninstall --force avr-gcc
+brew install avr-gcc@8
+brew link --force avr-gcc@8
+```
+
+### I just flashed my keyboard and it does nothing/keypresses don't register - it's also ARM (rev6 planck, clueboard 60, hs60v2, etc...) (Feb 2019)
+Due to how EEPROM works on ARM based chips, saved settings may no longer be valid. This affects the default layers, and *may*, under certain circumstances we are still figuring out, make the keyboard unusable. Resetting the EEPROM will correct this.
+
+[Planck rev6 reset EEPROM](https://cdn.discordapp.com/attachments/473506116718952450/539284620861243409/planck_rev6_default.bin) can be used to force an eeprom reset. After flashing this image, flash your normal firmware again which should restore your keyboard to _normal_ working order.
+[Preonic rev3 reset EEPROM](https://cdn.discordapp.com/attachments/473506116718952450/537849497313738762/preonic_rev3_default.bin)
+
+If bootmagic is enabled in any form, you should be able to do this too (see [Bootmagic docs](feature_bootmagic.md) and keyboard info for specifics on how to do this).