How to flash a kernel image without building Android from source I got the following msm kernel branch for my Nexus 7(flo)

      msm/remotes/origin/android-msm-flo-3.4-jb-mr2


added some files and then built an image(zImage). I then downloaded a factory image of Nexus 7 for JB - 4.3 (JSS15R) [This said razor which I dunno why. I thought it was flo]

Anyway I took the factory image. Split the boot.img file into the ramdisk.gz and zImage. Then I got the zImage from the kernel I build and replaced it with the zImage from the factory image. The I combined the zImage and ramdsik.gz to create the boot.img and tried to flash it. But the device goes into a bootloop.

The zImage works when I build android 4.3-JB from source. But aosp seems to miss some packages I need.

I wanted to know what I'm doing wrong and why android goes into a bootloop when I combine it with the factory image
You can't (reliably) combine a kernel with a ramdisk from a different kernel. The ramdisk contains the kernel modules you build, so it has to go with the exact same kernel build. If you build a kernel, you have to flash the ramdisk produced by that build along with the kernel image (and vice-versa).