Pascal Bare Bones: Difference between revisions

 

=== stub.asm ===

;/////////////////////////////////////////////////////////

;// //

KERNEL_STACK:

resb KERNEL_STACKSIZE

 

=== kernel.pas ===

{

/////////////////////////////////////////////////////////

 

end.

 

=== console.pas ===

{

/////////////////////////////////////////////////////////

 

end.

 

=== multiboot.pas ===

unit multiboot;

 

 

end.

 

=== system.pas ===

Since fpc-3.2.0 there was added necessary parts (in code block that part was highlighted by comment lines), because without them developer could met error like:

system.pas(18,1) (system) Parsing implementation of SYSTEM

system.pas(18,1) Fatal: Internal type "TEXCEPTADDR" was not found. Check if you use the correct run time library.

Fatal: Compilation aborted

Valid version of '''system.pas''' on 2022/12/29:

unit system;

 

);

end;

 

{ --- End of nessesary part --- }

 

implementation

 

end.

 

=== Linker script ===

linker.script

ENTRY(kstart)

SECTIONS

end = .; _end = .; __end = .;

}

 

=== Compiling and Linking the modules ===

Assemble stub.asm with:

 

* -f elf32 - needed ''exact'' under x86_64 systems to make correct object file

 

The Pascal modules with:

 

* -Aelf - instructs the internal fpc assembler to output an ELF object.;

 

Then link the whole thing with:

 

* --gc-sections -s, in combination with -CX -XXs above, eliminates RTTI symbols from resulting binary

 

In case of trouble linking under x86_64 system try this line:

 

'''Special sutuation''': last time after building '''binutils''' I've got error

i386-linux-ld --gc-sections -s -Tlinker.script -o kernel.obj stub.o kernel.o multiboot.o console.o system.o

ld: i386 architecture of input file `stub.o' is incompatible with i386:x86-64 output

ld: i386 architecture of input file `system.o' is incompatible with i386:x86-64 output

make: *** [Makefile:27: _LD] Error 1

That type of error can encounter if ''i386-linux-ld'' have wrong content. In my situation file content edited to:

#!/bin/bash

/full/path/to/compiled/cross/binutils/ld-new -A elf32-i386 $@

 

=== makeiso.sh ===

Also a good option is create a bootable ISO file to make run it with VirtualBox or qemu:

 

#!/bin/sh

TMPISO=iso

grub-mkrescue --output=pascal-kernel.iso iso

rm -rf $TMPISO

 

And simple run:

 

=== Alternative compiling: Makefile ===

 

Accumulating the lines from previous part we can make a '''Makefile''':

# Freepascal BareboneOS

# Makefile

rm -f *.ppu

 

 

==Further Steps==