FATAL: kernel too old

I used buildroot to generate bzImage and rootfs.cpio.gz, but always get "FATAL: kernel too old", no matter how I config the BR2_KERNEL_HEADERS_XXX and BR2_PACKAGE_HOST_LINUX_HEADERS_CUSTOM_XXX.

Google said the glibc need --enable-kernel, but buildroot already gave that. Then I found that my 3.13 kernel include/linux/version.h has LINUX_VERSION_CODE configured to something like 3.4....

I'm using Linux kernel checkout by git. It seems that the include/linux/version.h was generated when I were using 3.4, which I don't even remember when.

So if you got this error, and happen to be using linux source checkout by git, maybe try

git clean -xfd

Hopes this save your day, cause I've spent mine on this stupid reason. sigh.