Why iopmod-link is not adding .iopmod section it-sellf?

[fjtrujy]

Hello,

I was trying to go deeper using your marvelous tool, because it is a waste of effort and time to keep using the modified binutils/gcc version for the IOP CPU (speaking about the PS2DEV env).

We have been working separately, @rickgaiser, @uyjulian, myself, and probably more people, into trying to achieve something similar, using several approaches.

I honestly think that the best way is the way you are doing it, creating a tinny C app that makes the necessary changes to the ELF to adjust to the IOP requirements.

The first thing that I have found is that the iopmod-link is not creating the .iopmod section.
I was expecting that having _irx_id symbol in the binary, should be enough to have all the needed information for creating the .iopmod section, or maybe I'm confused....

Having the next example

#include <stdint.h>

struct irx_id {
	const char *n;
	uint16_t v;
};

#define IRX_VER(major, minor)	((((major) & 0xff) << 8) + ((minor) & 0xff))

struct irx_id _irx_id = {
    "DUMMY", 
    IRX_VER(2, 1)
};

int _start(int argc, char *argv[]) {
    return 0;
}

And compile it using:

mipsel-ps2-elf-gcc -D_IOP -fno-builtin -G0 -Wall  -I/Users/fjtrujy/toolchains/ps2/ps2dev/ps2sdk/iop/include -DDEBUG -O0 -g -msoft-float -mno-explicit-relocs -c main.c -o obj/main.o
mipsel-ps2-elf-gcc -D_IOP -fno-builtin -G0 -Wall  -I/Users/fjtrujy/toolchains/ps2/ps2dev/ps2sdk/iop/include -DDEBUG -O0 -g -msoft-float -mno-explicit-relocs -o dummy.elf obj/main.o -nostdlib

Then if we execute:

mipsel-ps2-elf-readelf -Ws dummy.elf | grep _irx_id
    20: 001000cc     8 OBJECT  GLOBAL DEFAULT    5 _irx_id

We have from there the offset where the information about the IRX_ID it is on the binary.

What do you think?

[frno7]

The iopmod-link tool was made simpler by putting most of the logic, including the .iopmod section, into the script/iop.ld linker script:

iopmod/script/iop.ld

Lines 15 to 24 in a5d2360

	.iopmod 0 (COPY) : ALIGN(4) {
	LONG (DEFINED(_module_id) ? _module_id : 0xffffffff);
	LONG (_module_init);
	LONG (_unknown); /* FIXME */
	LONG (SIZEOF(.text));
	LONG (SIZEOF(.data));
	LONG (SIZEOF(.bss));
	KEEP(*(.module.version))
	KEEP(*(.module.name))
	} :iopmod

I put some effort into making the whole IOP module command suite compatible with PS2DEV. So, for example, thbase_create that a Linux driver might use, is also, as an alias, perfectly linkable as CreateThread for PS2DEV drivers:

iopmod/include/iopmod/module/thread.h

Lines 6 to 9 in 67f3e6c

	id_(4) int thbase_create(const struct iop_thread *thread)
	alias_(CreateThread);
	id_(5) int thbase_delete(int thid)
	alias_(DeleteThread);

I’ve only enumerated a small subset of all IOP functions so far, though. The module init/exit code is simplified and streamlined compared to PS2DEV. The intention was that only minor changes were needed to compile PS2DEV code.