forums.ps2dev.org

radad · Posted: Mon Jan 12, 2009 6:11 pm Post subject: crt0 not working correctly

crt0 is supposed to call _ps2sdk_args_parse which sets up the initial cwd according to argv[0] but it isnt doing this. To test this I added the following line to the hello sample:

radad · Posted: Mon Jan 12, 2009 6:25 pm Post subject:

I have added a test to ps2sdk\ee\libc\regress so build and run this to see if it works on your system.

Lukasz · Joined: 19 Jan 2004 Posts: 248 Location: Denmark

I just tested this on Ubuntu, I modified your test_init to:

ragnarok2040 · Joined: 09 Aug 2006 Posts: 230

I'm getting the same behavior as you radad. When I commented out the .weak _ps2sdk_args_parse line in crt0.s, it worked. When I added a call to _ps2sdk_args_parse to main, getcwd worked.

I'm guessing what's happening is the linker doesn't explicitly look for the weak _ps2sdk_args_parse definition among library archives and since it's not explicitly called by any functions, the symbol is never actually added in the linking stage.

radad · Posted: Mon Jan 12, 2009 9:35 pm Post subject:

What compiler/OS are you using?

It is explicitly called in crt0.s, that should be enough for linker to make sure it is in there.

ragnarok2040 · Joined: 09 Aug 2006 Posts: 230

Archlinux x86-64, using a 32-bit standard ps2toolchain compiler on a chroot.

The .weak pseudo-op just tells it to use the definition it has until a global definition supercedes it from user code, or another weak definition from user code, which has to be seen first, supercedes it. Otherwise the weak definition in crt0.s holds sway.

When _ps2sdk_args_parse is called by user code, then the linker searches for the symbol definition, finding the weak one in init.o. Since it finds the weak symbol linked in from init.o from libc first, it supercedes the one defined in crt0.s which is linked in later which causes the code to work.

It's just the matter of placing the other weak _ps2sdk_args_parse call somewhere so it gets linked in prior to crt0.s. Adding _ps2sdk_args_parse to _ps2sdk_stdio_init() seems to fix it, though.

Edit:
Just to make sure, I called it with some false args to see what would happen, but it parsed the args provided by ps2link correctly.

radad · Posted: Tue Jan 13, 2009 6:29 am Post subject:

Im having the same issue with _ps2sdk_stdio_init though. It too uses a weak definition in crt0.s.

ragnarok2040 · Joined: 09 Aug 2006 Posts: 230

Hrmm, using weak definitions in the crt0.s was a way to get the crt0.o to compile without ps2sdk as well, according to chp. Unfortunately, it depends on the proper definitions being defined prior to crt0.o being linked when compiling with ps2sdk.

Also defining the symbols in crt0.s as .globl prior to defining a .weak symbol might also be causing trouble since global definitions override weak definitions. It didn't seem to make any difference after changing them, though.

I changed it to use .weakext instead. It seems to work fine now. Your clock example was working, and only 2 tests failed, tests 6 & 8. I was getting 4 tests failing with _ps2sdk_args_parse not being defined, and 3 tests failing after that, so I guess libc wasn't being initialized quite right.

ragnarok2040 · Joined: 09 Aug 2006 Posts: 230

Looks like a small oversight in fseek causes it to fail when it actually works.

The line
if (ret > 0)
should be
if (ret >= 0)

Edit3:
Fseek regression test problem was related to my version of ps2client so I removed my previous code.

radad · Posted: Thu Jan 15, 2009 7:01 pm Post subject:

committed rev 1508

radad · Posted: Thu Jan 15, 2009 7:27 pm Post subject:

This has broken cpp builds for me. I get this error:

ragnarok2040 · Joined: 09 Aug 2006 Posts: 230

I'm pretty sure _init and _fini are defined in crti.o in ee/lib/gcc-lib/ee/3.2.2/. Are you using the -nostartfiles flag when linking instead of -mno-crt0?

The best option for building C++ projects with -nostartfiles right now is defining an empty _init and _fini in your project somewhere.

ragnarok2040 · Joined: 09 Aug 2006 Posts: 230

Looks like that's normal, :?, never noticed it before, but I haven't dabbled with low-level C++ stuff. The linkmaps indicate that _init and _fini get defined normally by crti.o when using .weak _init and .weak _fini and when using the flag -mno-crt0. Changing them back to .weak shouldn't be a problem, :D.

I tested using some global class instances to make sure.

I pm'd oobles but haven't gotten a response yet. I made a patch, http://homebrew.thewaffleiron.net/ragnarok2040/crt0.patch.gz.

This should fix builds using -nostartfiles that don't rely on global objects.

radad · Posted: Sat Jan 17, 2009 9:58 am Post subject:

That fixes it, thanks. I have checked it in.

Give oobles a bit of time, he doesnt check very often.

On a slightly different topic. Anybody know why this section exists in iop/Rules.make

ragnarok2040 · Joined: 09 Aug 2006 Posts: 230

Hrmm, weird. Since ps2sdk uses LDFLAGS for CFLAGS when linking and CFLAGS for CFLAGS when compiling object code, I'm guessing it's to ensure that gcc doesn't try to optimize code for their builtin functions during both stages. It should be part of the CFLAGS for the older toolchains as well, then. Perhaps the behavior changed where gcc-3.2.2 does some optimizing during object code generation for builtin functions.

I'm not sure why LDFLAGS_TARGET was added since "-fno-builtin" is already in the original LDFLAGS. I'm pretty sure -march wasn't supported by the mips target in older IOP toolchains and -mcpu was deprecated in gcc-3.2.2.

Changing it to: