Using both "mainline" and "stock" linux kernels

FesterBester38

I'd like to make some tests with both "stock" and "mainline" linux kernels. But I'm a real rookie for that matter and I don't want to 'brick' my firefly board...

I don't know if it is possible to define a dual-boot configuration for both kernels residing on the eMMC. Maybe a simpler way to live with both kernels could be to install everything needed for the "mainline" kernel on an SDCARD leaving the eMMC untouched. In the tutorials I've seen at some places on this forum I don't see how I can tell that I want everything written to an SDCARD instead of the eMMC.

What I've done so far is to flash the last u-boot (RK3288UbootLoader_V2.19.01.bin) using upgrade_tool without changing anything else. The stock kernel is still booting. I've also compiled the "mainline" kernel (following the Wiki instructions) but I see that cmdline parameters (tty name, partitions name and size) for the "stock" firefly (dual boot android/linux) are really different than those required for the "mainline" linux kernel.  How are these parameters used? Are they used to create the partitions, or set the size of those partitions? Or are they just a "copy" of sizes determined somewhere else?

I suppose that if I flash the parameters needed by the "mainline" kernel then I won't be able anymore to boot on the "stock" kernel. Right?

Thx