# Second CPU core missing - Technexion PICO-PI-IMX7 - Yocto **URL:** \ **Category:** General Discussions\ **Created:** [March 22, 2019, 8:28pm UTC](https://hub.mender.io/t/second-cpu-core-missing-technexion-pico-pi-imx7-yocto/936 "2019-03-22T20:28:07Z")\ **Posts on this page:** 1\ **Showing post:** 8
**Author:** ![Bart](https://avatars.discourse-cdn.com/v4/letter/b/f19dbf/32.png) [@Bart](https://hub.mender.io/u/Bart)\ **Post date:** [September 23, 2020, 2:45pm UTC](https://hub.mender.io/t/second-cpu-core-missing-technexion-pico-pi-imx7-yocto/936/8 "2020-09-23T14:45:40Z")
I have tried this suggestion: > [@Bluetooth on Technexion PICO-PI-IMX7](https://hub.mender.io/t/bluetooth-on-technexion-pico-pi-imx7/937/3): > > If it can help anyone, I (finally) found how to enable Bluetooth. You need to enable/reset the bluetooth controller using GPIO: echo 114 \> /sys/class/gpio/export echo "out" \> /sys/class/gpio/gpio114/direction cd /sys/class/gpio/gpio114 echo 1 \> value && sleep 1 && echo 0 \> value && echo 1 \> value There is probably a better way to do this, through rfkill, but I didn’t know anything about kernels and yocto a few weeks ago - so still learning. Then, btattach -B /dev/ttymxc6 -P bcm & Make sure… Three observations: - The 2nd core does indeed start, both CPU’s in HYP mode. - If I only update my board with the .mender file the u-boot config does not get updated. So on reboot the old u-boot config still applies. I need to replace the bootloader and SPL with dfu to the new version. Is this behaviour expected? I was expecting the new u-boot to get updated with the .mender file as well. - caam behaves differently depending on CONFIG\_ARMV7\_BOOT\_SEC\_DEFAULT CONFIG\_ARMV7\_BOOT\_SEC\_DEFAULT=y: (so single core active) ``` root@imx7d-pico:/lib# dmesg | grep caam [2.444686] caam 30900000.caam: Entropy delay = 3200 [2.450039] caam 30900000.caam: Instantiated RNG4 SH0 [2.509452] caam 30900000.caam: Instantiated RNG4 SH1 [2.514527] caam 30900000.caam: device ID = 0x0a16030000000000 (Era 8) [2.521108] caam 30900000.caam: job rings = 3, qi = 0 [2.672765] caam algorithms registered in /proc/crypto [2.687239] caam_jr 30901000.jr0: registering rng-caam [2.694308] caam 30900000.caam: caam pkc algorithms registered in /proc/crypto ``` CONFIG\_ARMV7\_BOOT\_SEC\_DEFAULT not defined: (dual core active) ``` [2.515625] caam 30900000.caam: Entropy delay = 3200 [2.551627] caam 30900000.caam: failed to acquire DECO 0 [2.556969] caam 30900000.caam: failed to instantiate RNG ``` The rescue image from Technexion does boot up the board with the two CPU’s in SVC mode, but it is unclear for me how they do that. --- _[View the full topic](https://hub.mender.io/t/second-cpu-core-missing-technexion-pico-pi-imx7-yocto/936)._