[yocto] understanding recipes

[jfabernathy]

I'm trying to understand the concept of creating a recipe and having it 
included in the build I do.

For example, suppose I want to create the meta-intel/meta-cedartrail BSP 
with the core-image-minimal image, but I wanted to include hello world 
as shown in 3.1.2 Autotooled Package section of the Poky reference Manual.

Where do I put the recipe file?  I'm guessing a recipe-jfa directory at 
the same level as the meta-cedartrail recipe-core, recipe-kernel, 
recipe-graphic, recipe-bsp?

I'm also assuming that helloworld.bb file would contain:

      DESCRIPTION = "GNU Helloworld application"
      SECTION = "examples"
      LICENSE = "GPLv2+"
      LIC_FILES_CHKSUM = "file://COPYING;md5=751419260aa954499f7abaabaa882bbe"
      PR = "r0"

      SRC_URI = "${GNU_MIRROR}/hello/hello-${PV}.tar.gz"

      inherit autotools gettext


So where do the values of ${GNU_MIRROR|, and ${PV} get set correctly?

And what does the following line do or require me to do:

  LIC_FILES_CHKSUM = "file://COPYING;md5=751419260aa954499f7abaabaa882bbe"

Is this all that is needed to get helloworld put into /usr/bin so it can 
be executed at the command line when the image is booted?

Jim A