{{Board Specific Information|text=Please note that , for NELK < 2.0.0, pin mux configuration is applied in both U-Boot stage (1st and 2nd). When changing pin mux configuration for your custom board, please be sure to update both binaries}} {{Board Specific Information|text=Starting from NELK 2.0.0, 1st stage only configure a minimal set of pins, the one that are required to start correctly the 2nd stage. }}  === Multiple Pin Mux Support === {{ImportantMessage|text=The <pre class="workstation-terminal">make linux</pre> command will fail complaining about a missing .config file if launched before preparing the kernel configuration as described above}} To allow greater flexibility, starting from u-boot released with [[Naon Embedded Linux Kit (NELK)|NELK]] 2.0.0 user can choose which pin mux to use by setting the '''naon_host''' U-Boot environment variable. If this variable is empty or not correctly configured, U-Boot will warn the user and it does not apply any pin mux configuration (apart the default one configured by 1st stage). <pre class="board-terminal">U-Boot 2010.06 (Aug 10 2012 - 09:09:58) [nelk-2.0.0-rc2] TI8148-GP rev 2.1 ARM clk: 600MHzDDR clk: 400MHz I2C: readyDRAM: 512 MiBNAND: Searching for NAND device @ GPMC CS:0HW ECC BCH8 Selected1024 MiBMMC: OMAP SD/MMC: 0WARNING!! no valid pin mux defined, please configure 'naon_host'environment variable to the correct value, save the environmentand reboot or some peripheral may not work correctly</pre> In this case, many peripheral will not work correctly, but the user is safe to plug the [[Category:Naon|Naon]] module in any board, due the fact that all pin are muxed in safe mode. To configure, e.g., for [[Category:NaonEVB-Mid|NaonEVB-Mid]] the user should set the ''naon_host'' environment variable accordingly: <pre class="board-terminal">NAON#setenv naon_host evb_midNAON#saveenvSaving Environment to SPI Flash...Erasing SPI flash...Writing to SPI flash...done</pre> {{Board Specific Information|text=Please note that pin mux is applied only at boot time, for this reason, after configuring the environment variable, the user should reset the board to apply the settings.}}  <pre class="board-terminal">NAON#setenv naon_host evb_midNAON#saveenvSaving Environment to SPI Flash...Erasing SPI flash...Writing to SPI flash...doneNAON#resresetting ...CCC U-Boot 2010.06 (Aug 10 2012 - 09:09:19) [nelk-2.0.0-min-rc2] TI8148-GP rev 2.1 ARM clk: 600MHzDDR clk: 400MHz DRAM: 512 MiBUsing default environment Hit any key to stop autoboot: 08192 KiB AT45DB642D at 0:0 is now current device## Starting application at 0x81000000 ...  U-Boot 2010.06 (Aug 10 2012 - 09:09:58) [nelk-2.0.0-rc2] TI8148-GP rev 2.1 ARM clk: 600MHzDDR clk: 400MHz I2C: readyDRAM: 512 MiBNAND: Searching for NAND device @ GPMC CS:0HW ECC BCH8 Selected1024 MiBMMC: OMAP SD/MMC: 0MUX: configuring for evb_midNet: Detected MACID:0:50:c2:1e:af:afcpswHit any key to stop autoboot: 0NAON#</pre>