Android OEMs are required to release the kernel source code every time they push a new Android version to a device. It includes any modifications they've made and its what tinkerers then use to build custom ROMs and other mods. Some OEMs are quick to release the code after an update, whereas some drag their heels. In this instance, Samsung has been impeccably fast.
After a thorough beta program, Samsung finally started rolling out Android 8.0 Oreo to the Galaxy S8 and S8+ yesterday. That would usually mean we'd have to wait at least a few weeks to get the source code, but not this time. Samsung has outdone itself and already made it available.
This won't mean much to most of you, but if you like playing around with custom ROMs you'll be pleased to know Oreo-based mods will come along sooner rather than later now the kernel source code is available. For those who know what they're doing, download links are below: