How patching works in yocto

Question

I am using BBB to understand the yocto-project. I am not sure how patching works. This is my project directory

├── meta-testlayer
├── poky

Answer 1

First, create the patch:

diff -u helloworld.c newhelloworld.c > helloworld.patch

or using Git (replace x by the number of commits you want to extract a patch):

git format-patch -x

Two ways to apply the patch:

• Put it into your test-layer, add a line on your .bb file: SRC_URI += " file://example.patch "

• Put it in another layer, but it's only needed if it isn't your layer (meta-oe, meta-fsl, meta-qt...)

For this case, use in your .bbappend file:

FILESEXTRAPATHS_prepend := "${THISDIR}/${PN}:"
SRC_URI += " file://helloworld.patch "