Add a magic string for the ISO kernel cmdline:

This adds a 1024 character string that is used
as a known string to match on when binary patching
the Hook ISO. This means that a service needs to
binary patch the Hook ISO that is built with the
cmdline. In the Tinkerbell stack this is functionality
that is being built into Smee.

Signed-off-by: Jacob Weinstock <[email protected]>

Author: jacobweinstock

linuxkit-templates/hook.template.yaml

@@ -14,7 +14,9 @@
 
 kernel:
   image: "${HOOK_KERNEL_IMAGE}"
-  cmdline: "this_is_not_used=at_all_in_hook command_line_is_determined_by=ipxe"
+  # The cmdline is a random string with 1024 characters. It is used for binary patching in the ISO image.
+  # The kernel and initrd don't use this cmdline. The bootloader that loads the kernel determines the cmdline that will be used.
+  cmdline: "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"
 
 init:
   # this init container sha has support for volumes