# Decide kernel image in bootloader

**URL:** <https://forums.developer.nvidia.com/t/decide-kernel-image-in-bootloader/76018>\
**Category:** Jetson TX2\
**Created:** [June 6, 2019, 3:34pm UTC](https://forums.developer.nvidia.com/t/decide-kernel-image-in-bootloader/76018 "2019-06-06T15:34:31Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![euskadi](https://sea2.discourse-cdn.com/nvidia/user_avatar/forums.developer.nvidia.com/euskadi/32/13118_2.png) [@euskadi](https://forums.developer.nvidia.com/u/euskadi)\
**Post date:** [June 6, 2019, 3:34pm UTC](https://forums.developer.nvidia.com/t/decide-kernel-image-in-bootloader/76018/1 "2019-06-06T15:34:31Z")

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I wanted to know whether it is possible or not to decide between two kernel images at bootloader stage. Something like having a grub menu to decide between two kernel images, just to avoid having to flash the TX2 again if the Image is wrongly built.

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**Author:** ![linuxdev](https://sea2.discourse-cdn.com/nvidia/user_avatar/forums.developer.nvidia.com/linuxdev/32/10243_2.png) [@linuxdev](https://forums.developer.nvidia.com/u/linuxdev)\
**Post date:** [June 6, 2019, 7:32pm UTC](https://forums.developer.nvidia.com/t/decide-kernel-image-in-bootloader/76018/2 "2019-06-06T19:32:50Z")

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I hesitate to answer since some content now requires being signed, but take a look at “/boot/extlinux/extlinux.conf” (I have not tested on recent releases). You might duplicate the first entry, and make an alternate entry. The alternate might look like the following, with “Image” renamed:

```auto
LABEL primary
      MENU LABEL primary kernel
      LINUX <b>/boot/Image-custom</b>
      APPEND ${cbootargs} root=/dev/mmcblk0p1 rw rootwait rootfstype=ext4

```

Keep in mind that all modules must be found in “/lib/modules/$(uname -r)/”, and thus if this custom Image results in the same “uname -r”, then you won’t need a separate module directory…but if there is a difference, then modules must also be added.

Selecting alternate entries is only available via serial console by interrupting U-Boot at the critical moment with a keystroke. If you interrupt before it asks for kernel to select, then simply continue with the “boot” command (kernel selection phase immediately follows this). Serial console information is here:  
[http://www.jetsonhacks.com/2017/03/24/serial-console-nvidia-jetson-tx2/](http://www.jetsonhacks.com/2017/03/24/serial-console-nvidia-jetson-tx2/)

It is possible that the alternate kernel will be selected, but then rejected if signing is getting in the way.

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**Author:** ![nadeemm](https://sea2.discourse-cdn.com/nvidia/user_avatar/forums.developer.nvidia.com/nadeemm/32/367020_2.png) [@nadeemm](https://forums.developer.nvidia.com/u/nadeemm)\
**Post date:** [October 18, 2021, 6:32pm UTC](https://forums.developer.nvidia.com/t/decide-kernel-image-in-bootloader/76018/3 "2021-10-18T18:32:41Z")

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Closed on October 18, 2021, 6:32pm UTC