I recomplie the Raspbian kernel for Cirrus Logic audio card, following this description.
https://github.com/CirrusLogic/rpi-linux/wiki/Building-the-code
and I wonder what does mkknlimg exaclty do.
and I found these:
"Note that DT and ATAGs are mutually exclusive. As a result, passing a DT blob to a kernel that doesn't understand it causes a boot failure. To guard against this, the loader checks kernel images for DT-compatibility, which is marked by a trailer added by the mkknlimg utility; this can be found here, or in the scripts directory of a recent kernel source tree. Any kernel without a trailer is assumed to be non-DT-capable." at https://www.raspberrypi.org/documentation/configuration/device-tree.md
What I found: From ATAGs I found that They are used to pass physical memory layouts to the kernel at booting process on ARM arch, and they are incompatible with the Device Tree blob.
My question: What is a "trailer"?