README.md: Add paragraph for the 'xilinx' license flag

This paragraph documents the existence of recipes that rely on closed or
otherwise restricted source content that can be used to compile images
for targets.

The content has specific licensing and legal requirements that are
outside the ability or sanity of enforcement in OpenEmbedded or Yocto
and as such is up to each individual user to review and comply with.
This might include EULA, Export Compliance, NDAs, Redistribution, etc.

Generally speaking this content is going to be protected by Xilinx's web
download service which requires an account.

Signed-off-by: Nathan Rossi <nathan@nathanrossi.com>
Tested-by: Alistair Francis <alistair.francis@xilinx.com>
Acked-by: Alistair Francis <alistair.francis@xilinx.com>
Acked-by: Manjukumar Matha <manjukumar.harthikote-matha@xilinx.com>

1 files changed, 27 insertions, 0 deletions

diff --git a/README.md b/README.md
index eef02142..fd54577a 100644
--- a/README.md
+++ b/README.md
@@ -56,3 +56,30 @@ This layer depends on:
         URI: git://git.openembedded.org/openembedded-core
         layers: meta
 
+Recipe Licenses
+===============
+
+Due to licensing restrictions some recipes in this layer rely on closed source
+or restricted content provided by Xilinx. In order to use these recipes you must
+accept or agree to the licensing terms (e.g. EULA, Export Compliance, NDA,
+Redistribution, etc). This layer **does not enforce** any legal requirement, it
+is the **responsibility of the user** the ensure that they are in compliance
+with any licenses or legal requirements for content used.
+
+In order to use recipes that rely on restricted content the `xilinx` license
+flag must be white-listed in the build configuration (e.g. `local.conf`). This
+can be done on a per package basis:
+
+        LICENSE_FLAGS_WHITELIST += "xilinx_pmu-rom"
+
+or generally:
+
+        LICENSE_FLAGS_WHITELIST += "xilinx"
+
+Generally speaking Xilinx content that is provided as a restricted download
+cannot be obtained without a Xilinx account, in order to use this content you
+must first download it with your Xilinx account and place the downloaded content
+in the `downloads/` directory of your build or on a `PREMIRROR`. Attempting to
+fetch the content using bitbake will fail, indicating the URL from which to
+acquire the content.
+