/joh'liks/ n.,adj. 386BSD
PORTING UNIX TO THE 386: A PRACTICAL APPROACH
William & Lynne Jolitz
We didn't just load and debug the kernel; we chose to prove portions first. That way we learned the dependances first, and could try alternatives seperately. Later we used the same means to revise them later.
Prevaricating with the Standalone System
The standalone system also provides us with a test bed for trying many different ideas which can satisfy the mechanisms used in the BSD operating system kernel, for we can then selectively test these mechanisms individually. Otherwise, we would be forced to test them all together within the operating system. Thus, as we vary our approach, we can determine whether each method satisfies our basic specification conditions and whether implementation is feasible for our project.|
Over the course of this project, the support strategies for device-interrupts configuration and process context-switching changed drastically as we began to notice the degree of difference between porting BSD to a 386 and porting BSD to more "conventional" architectures. In fact, we were still using the standalone system to find unintended interactions in our 386 hardware-features support code long after we had 386BSD self-compiling.
Another valuable aspect of this test bed is we can benchmark competitive solutions to the same kernel support mechanism sans other interactions. This was useful in selecting appropriate context switch, interrupt control, and virtual memory system code.