Patch set to ease replacement of BCC compiler

Patch set to ease replacement of BCC compiler

[Juan Perez-Sanchez]

Hi,

I will send a set of 5 patches aimed to ease the transition
to other C compiler. The compilers considered are open-watcom
and ia16-unknown-elks-gcc.

This is not a port to use another compiler, BCC is still the
only compiler able to produce the kernel image. Even if a file
is compiled without errors, there are issues such as calling
function conventions, register usage and naming conventions
in assembly code that were not solved.

Now, the alternative compilers can compile all C files in the
source tree with only a few warnings, provided that inline
assembly is not used. The compilers detected several cases of
code that never executes, and deleting this code reduces code
size.

The largest roadblocks for using other compiler are the
assembly code and the inline assembly facility in BCC. I did
some changes aimed to have "only C" files and "only assembly"
files. The few files with mixed languages have C functions
without inline assembly or complete assembly functions. I also
did changes to eliminate some assembly code.

After the modifications, code size was reduced in 240 bytes,
data reduced in 16 bytes and bss increased in 4 bytes.

Patches should be applied in the correct order: starting with
elks-3t.patch and ending with elks-3x.patch

All kernel Images builded without errors using BCC. Every kernel
was tested with QEMU and PCE emulators. Also in a PPro pc
booting from floppy.

Greetings,

Juan

Re: Patch set to ease replacement of BCC compiler

[u-vpoa]

On Thu, May 21, 2015 at 12:47:35AM -0500, Juan Perez-Sanchez wrote:
> I will send a set of 5 patches aimed to ease the transition
> to other C compiler.

Surely a useful step.

> The compilers considered are open-watcom
> and ia16-unknown-elks-gcc.

We should keep in mind that open-watcom has a minefield license.
One ought to be careful to not introduce any dependency on it.

Juan, wonder if you tried/considered Coherent C compiler?

Rl

Re: Patch set to ease replacement of BCC compiler

[u-vpoa]

On Thu, May 21, 2015 at 12:47:35AM -0500, Juan Perez-Sanchez wrote:
> After the modifications, code size was reduced in 240 bytes,
> data reduced in 16 bytes and bss increased in 4 bytes.

> All kernel Images builded without errors using BCC. Every kernel
> was tested with QEMU and PCE emulators. Also in a PPro pc
> booting from floppy.

Good work!

Rl

Re: Patch set to ease replacement of BCC compiler

[Juan Perez-Sanchez]

On Thu, May 21, 2015 at 1:23 AM,  <u-vpoa@aetey.se> wrote:
>
>> The compilers considered are open-watcom
>> and ia16-unknown-elks-gcc.
>
> We should keep in mind that open-watcom has a minefield license.
> One ought to be careful to not introduce any dependency on it.
>
> Juan, wonder if you tried/considered Coherent C compiler?
>
No, and the reason is that I don't have any idea of how much work is
needed to make it functional under linux.

Another candidate is TACK, many times proposed in this list. It would
be nice to have staticly linked binaries for linux available.

Juan