Reproduce a previous release

In this example, we will recreate linux-rockchip 5.10.110-5 package.

1. Find the original GitHub release for the desired package
   For our example, it is located at https://github.com/radxa-pkg/linux-rockchip/releases/tag/5.10.110-5.

2. From the release pages, you will see multiple packages.
   We will focus on the top 2 packages:

3. As our packages are built with bsp and radxa/kernel, there are 2 git commits that we need to find out to accurately reproduce those packages:
   Since the real package (the one with larger file size) is closely related to radxa/kernel, 1932709cf is the commit for it.
   Since the meta package (the one with smaller file size) is closely related to bsp, 3a557f6 is the commit for it.

4. We now have the following essential commit information:
   radxa/kernel: 1932709cf
bsp: 3a557f6

5. However, fork.conf only takes full commit hash. So click the radxa/kernel link above, and click Browse files button on GitHub page, that will get you the full commit hash in the URL bar: radxa/kernel: 1932709cf7d98d0d92952bba38d990d938fabc58

6. We can also check the content of overlay.sh to find the commit used for radxa/overlays:
   radxa/overlays: 4940ae33e4def0fb9133faf68adf0c3421b61f06

7. We can now recreate the package:

git clone --recurse-submodules https://github.com/radxa-repo/bsp.git
cd bsp
# switch to bsp commit found above
git switch --detach 3a557f6
# replace BSP_BRANCH with radxa/kernel commit found above
sed -i "s/BSP_BRANCH.*/BSP_COMMIT='1932709cf7d98d0d92952bba38d990d938fabc58'/" linux/rockchip/fork.conf
./bsp linux rockchip
# the prepared kernel tree will be available under .src/linux