I'm trying to build a Bare Bones 'OS' via example.  Example says to compile with
"gdc -c kernel.main.d -o kernel.main.o -g"  I'm having trouble getting GDC all set up..as I'm a rank amateur.  So, I tried compiling the example below with DMD.  DMD spits out exceptions to the use of 'volatile'. DIP62 on D wiki says status:REJECTED for volatile.
Whats my work around here?  This is what I'm trying to do-> https:// wiki.osdev.org / D_Bare_Bones

Thanks for any help.

module kernel.main;

extern(C) void main(uint magic, uint addr) {
        int ypos = 0; //Starting points of the cursor
	int xpos = 0;
	const uint COLUMNS = 80; //Screensize
	const uint LINES = 25;

	ubyte* vidmem = cast(ubyte*)0xFFFF_8000_000B_8000; //Video memory address

	for (int i = 0; i < COLUMNS * LINES * 2; i++) { //Loops through the screen and clears it
			volatile *(vidmem + i) = 0;
	}

	volatile *(vidmem + (xpos + ypos * COLUMNS) * 2) = 'D' & 0xFF; //Prints the letter D
	volatile *(vidmem + (xpos + ypos * COLUMNS) * 2 + 1) = 0x07; //Sets the colour for D to be light grey (0x07)

	for (;;) { //Loop forever. You can add your kernel logic here
	}
}

On Thursday, 1 August 2019 at 03:04:27 UTC, Paul wrote:
> I'm trying to build a Bare Bones 'OS' via example.  Example says to compile with
> "gdc -c kernel.main.d -o kernel.main.o -g"  I'm having trouble getting GDC all set up..as I'm a rank amateur.  So, I tried compiling the example below with DMD.  DMD spits out exceptions to the use of 'volatile'. DIP62 on D wiki says status:REJECTED for volatile.
> Whats my work around here?  This is what I'm trying to do-> https:// wiki.osdev.org / D_Bare_Bones
>
> Thanks for any help.
>
> module kernel.main;
>
> extern(C) void main(uint magic, uint addr) {
>         int ypos = 0; //Starting points of the cursor
> 	int xpos = 0;
> 	const uint COLUMNS = 80; //Screensize
> 	const uint LINES = 25;
>
> 	ubyte* vidmem = cast(ubyte*)0xFFFF_8000_000B_8000; //Video memory address
>
> 	for (int i = 0; i < COLUMNS * LINES * 2; i++) { //Loops through the screen and clears it
> 			volatile *(vidmem + i) = 0;
> 	}
>
> 	volatile *(vidmem + (xpos + ypos * COLUMNS) * 2) = 'D' & 0xFF; //Prints the letter D
> 	volatile *(vidmem + (xpos + ypos * COLUMNS) * 2 + 1) = 0x07; //Sets the colour for D to be light grey (0x07)
>
> 	for (;;) { //Loop forever. You can add your kernel logic here
> 	}
> }

Accesses to peripheral regiters or memory need to be marked volatile. This tells the compiler that these operations have some other meaning than just store and load the data. Otherwise the compiler may reorder or remove operations.
Unfortunately the volatile feature was removed from the language some years ago. Instead, there are volatileLoad and volatileStore in core.bitop.

A simple program may work if all volatile words are just omitted and the program is compiled with all optimizations turned off. I made Volatile data type to access peripheral registers, you can see it here:
https://bitbucket.org/timosi/minlibd/src/default/tools/main/volatil3.d

Thank you.  I'll try that.