BKM: starting a new BSP
This is a practical 'quick start' on creating a new BSP. For detailed background and instructions on how to to formally do this, please see the BSP Developer's Guide [1] and the Kernel Manual [2]. This document is essentially a pragmatic distillation of those documents but oriented toward the mechanics of quickly getting the initial BSP infrastructure in place for a minimally functional new BSP.
Mostly it's a straightforward exercise:
- copy a meta-* subdirectory representing the metadata of the BSP
- add it as a layer and configure the build system to use it
- add or tweak the machine configuration and recipes in the layer to get things working
- create a specialized branch for the BSP in the kernel and add kernel metadata to customize it for the BSP
The final step above (dealing with the kernel) is actually the most time-consuming and least straightforward aspect of not only creating the initial BSP, but of maintaining it going forward, so much of this document will be dedicated to addressing that aspect of BSP creation/maintenance.
Starting Out
As mentioned in the BSP Developer's Guide, the easiest way to start a new BSP is to base it on a similar already-existing working BSP. For this guide, we'll essentially go through the steps used to create the BSP for the Fish River Island, which exists in its current form as meta-fishriver in the meta-intel repository.
For this particular BSP, a bit of background on the base hardware and its relationship with some similar Intel hardware, the Crown Bay platform, will be useful when describing how the fishriver BSP was created. For the purposes of this guide, the relevant components of the Crown Bay platform that we care about are the 'EG20T platform controller hub' (Top Cliff) which provides 'platform' components such as USB hardware and gigabit ethernet adapters, etc, and the processor, which in the case of the Crown Bay platform, is the E660 Atom 'Tunnel Creek' processor with on-board graphics. The Fish River Island I is also based on the Top Cliff, but instead of a Tunnel Creek processor, it uses a Z530 Atom 'eMenlow' processor.
