cross support:Porting Unix to the 386: Language Tools Cross Support
We describe the need and use of a cross-support environment to create 386 code from a non-386 machine, so as to create the initial binarys before our port can generate them.Why Develop Cross-Tools?
We used another proven UNIX system - a Symmtric 375, to cross compile 386 code (bootstrap, kernel, shell, utilities) to get the first system running.386BSD Cross-Tools Goals
Our use of cross-tools was simply to bootstrap onto the 386 - not to perfect ongoing development. So, if we found a problem with the tool, we bypassed it with a one time workaround - cross tools didn't need to work for everything.What's in the Tool Chest?
The tool chest for 386BSD cross support included compiler, assembler, loader, libraries and include files. It did not include an emulation environment.Cross-Support Methodology
Our methodology was to prove that we could get a usable, tested executable across onto the native machine to be useful there. As we found and fixed, this methodology sped getting enough good and working native components, such that we could begin native development.Which C Standard?
BSD started before ANSI C, and still seems wedded to it even in 2006! GCC with the "traditional" flag didn't quite work, so we compromised.Other Cross-Support Issues
We started with a cheap lunchbox PC with a 40MB drive, and had to change as we exhausted serial downloads and DOS was squeezed of the drive for space for BSD.Validating GCC for Use in a Cross-Environment GCC Support Calls to Replace GNULIB
We used GCC but not GNULIB, so we had to roll our own support code as needed.Choosing a Sensible Cross-Host
Our Symmetric 375 was close but not identical to a 386 - its National 32000 series microprocessor was different. Yet it was a good choice for cross host in a cross development environment.Where Do We Go From Here
With cross tools we could make utility programs for our nascent system. The next step would be incorporating them into a filesystem so that they could run on the native 386, with the kernel program.Porting Unix to the 386: The Initial Root Filesystem
We build the first instance of the root filesystem - before any operational system is present on the 386 to build one. Part of the bootstrapping cycle of getting up the first running system on a new architecture.Porting Unix to the 386: Research and the Commercial Sector
Understanding the boundary between research and development with BSD, and where a balance between commercial efforts can be struck.