Remove pc386 BSP variant

[Sebastian Huber]

Remove the pc386 BSP (bsps/i386/pc386/config/pc386.cfg). The BSP for the historic Intel 80386 (​https://en.wikipedia.org/wiki/Intel_80386).

The reasons are:

• Obsolete platform.
• GCC wants to get rid of this processor.
  • ​http://gcc.gnu.org/ml/gcc/2012-12/msg00132.html
  • ​https://lists.rtems.org/pipermail/devel/2013-August/004124.html
• It is the only user of bin2boot. Host tools complicate the build system.

[Joel Sherrill]

Delete bin2boot. But I adamantly oppose removal of this port and bsp until x86_64 is available.

GCC is considering removal of other targets including m68k. Even with it removed, we could choose to stick with an old toolset.

[Sebastian Huber]

I don't want to remove all pc386 BSP variants. This ticket is about the removal of bsps/i386/pc386/config/pc386.cfg. I don't want to touch the pc486 for example.

[Sebastian Huber]

I just realized that the bin2boot is used by all i386 BSPs, see also #3410.

[Chris Johns]

The post link process is badly defined and implemented inconsistently in the BSPs that supported it. I suspect it is only of use in a limited number of cases and in specific use cases for some hardware configurations. The data in the .cfg files is important and should be kept until we can find a suitable way to export the important details to all application build systems.

I do not think I have used the bin2boot method of booting a PC and current use the standard ELF file our link process generates via the iPXE boot loader that is loaded by a BIOS PXE loader. All this stuff is widely available, clearly documented and supported.

[Sebastian Huber <sebastian.huber@…>]

In 3d703f4/rtems:

bsp/pc386: Remove bin2boot support

Update #3408.
Close #3410.