Android source code tree structure

I have downloaded Android source code but I don't find the "Kernel Directory" in the top level directory of the source code tree. Is it ok? Or is it missing?

/mydroid$ find . -name kernel
./bionic/libc/kernel
./vendor/htc/sapphire-open/kernel
./vendor/htc/dream-open/kernel
./dalvik/libcore/luni-kernel/src/te开发者_StackOverflow社区st/java/tests/api/org/apache/harmony/kernel
./dalvik/libcore/luni-kernel/src/main/java/org/apache/harmony/kernel
./prebuilt/android-arm/kernel
./prebuilt/android-x86/kernel
./device/htc/passion/kernel

default.xml in https://android.googlesource.com/platform/manifest does not point to the kernel, so repo would not automatically download it. Most kernel trees are specific to machines anyway.

See http://elinux.org/Android_Kernel_Download for information on getting the right kernel.

git clone https://android.googlesource.com/kernel/common.git kernel