LDFLAGS Central

taviso · Posted: Wed Jul 16, 2003 4:28 pm Post subject: LDFLAGS Central

You may or may not be aware that the next versions of portage will probably support $ASFLAGS and $LDFLAGS, options that are usually passed to the assembler and linker during the build process.

There are even patches on gentoo-dev to add this support, although you can still use $LDFLAGS and $ASFLAGS without this patch, just by setting them in /etc/make.conf.

http://marc.theaimsgroup.com/?l=gentoo-dev&m=105793517425320&w=2

$ASFLAGS is not particularly useful, it will probably be supported only for completeness. $LDFLAGS, however, could be useful and I have been experimenting recently to see what exactly can be done with them.

First of all, you can benchmark dynamic linking using the $LD_DEBUG variable, for example:

aardvark · Guru Joined: 30 Jun 2002 Posts: 576

I don't quite understand your line here. One would not expect a "," between -z and combreloc.

taviso · Posted: Wed Jul 16, 2003 5:16 pm Post subject:

aardvark · Guru Joined: 30 Jun 2002 Posts: 576

Ok, but would

taviso · Posted: Wed Jul 16, 2003 5:47 pm Post subject:

aardvark · Guru Joined: 30 Jun 2002 Posts: 576

deadbeef · n00b Joined: 14 Nov 2003 Posts: 1

I have to rebuild my system tomorrow, I'm going to try this out.

I'll do some benchmarks before+after & post back any results.

-0xdb

pennedinil · Tux's lil' helper Joined: 08 Aug 2003 Posts: 95

For completeness, should the flags not be

Hackeron · Guru Joined: 01 Nov 2002 Posts: 307

breaks emacs compile! -- everything else so far compiles just fine, but emacs says:

dalek · Posted: Wed Jan 19, 2005 11:14 am Post subject:

This is my ldflags.

taskara · Posted: Wed Jan 19, 2005 11:36 am Post subject:

LDFLAGS are not hardware specific afaik.

So they will work on any system.

The initial post from 2003 suggests

wrc1944 · Posted: Wed Jan 19, 2005 8:46 pm Post subject:

After much thought, and a lot of reading, I just put

LDFLAGS="-Wl,-O1"

in my make.conf, and started an emerge -e system. I'm cruising along at 21 out of 103 to go, but am not seeing any LDFLAGS related stuff in the gcc output.

What output am I supposed to be looking for, and does it even show up in the output, like the CFLAGS do? In other words, how do I know if I'm really compiling with the LDFLAGS I set in .make.conf?

One more thing: I know it's -Wl (letter L, not numeric 1), but can't find anything regarding if -o1 is -o(letter o), or -0(numerical zero). Since I didn't know which, I pasted what was in the LDFLAGS post, and it seems to be working (shows up in emerge --info), but since I'm not seeing any LDFLAGS output I can identify, I'm still wondering if I have it correct.

Thanks,
wrc1944
_________________
Main box- AsRock x370 Gaming K4
Ryzen 7 3700x, 3.6GHz, 16GB GSkill Flare DDR4 3200mhz
Samsung SATA 1000GB, Radeon HD R7 350 2GB DDR5
OpenRC Gentoo ~amd64 plasma, glibc-2.40-r5, gcc-14
kernel-6.12.8 USE=experimental python3_12.7-final-0

SoTired · Apprentice Joined: 19 May 2004 Posts: 174

The ldflags will only show up during an emerge during linking, which generally is very quick/easy to miss. If you watch an emerge and it gets to a point where you see a lot of .o files on one line, there should be ldflags there as well.

The 'O' is a capital letter o, just like O for gcc (cflags) they both turn on optimizations.

As reference, an example from my current compilation of gtk+:

taipan67 · Posted: Thu Jan 20, 2005 9:19 pm Post subject:

When did '-z combreloc' get edited out of the original post, & why?

I ask because i've just started a very careful rebuild, & had to remove it from my LDFLAGS to get 'glibc' to compile (it's doing so now - i hope it finishes okay...

)
_________________
"Anyone who goes to see a psychiatrist should have their head examined!"

taipan67 · Posted: Thu Jan 20, 2005 10:02 pm Post subject:

taviso · Posted: Thu Jan 20, 2005 10:58 pm Post subject:

taipan67 · Posted: Thu Jan 20, 2005 11:13 pm Post subject:

wrc1944 · Posted: Thu Jan 20, 2005 11:45 pm Post subject:

SoTired,
Thanks for the info. I got most of the way through emerge -e system, and came back in and my computer was off. Apparently my power supply failed, so I ordered a new 580 watt monster, and presently am back to my old mandrake backup box for a few days, so I can't see how these LDFLAGS work.. Haven't used this older box in about 3 months, and even though it has Mandrake 10.1 on it (just did it today), I'm now reminded of why I went to Gentoo Almost two years ago.
_________________
Main box- AsRock x370 Gaming K4
Ryzen 7 3700x, 3.6GHz, 16GB GSkill Flare DDR4 3200mhz
Samsung SATA 1000GB, Radeon HD R7 350 2GB DDR5
OpenRC Gentoo ~amd64 plasma, glibc-2.40-r5, gcc-14
kernel-6.12.8 USE=experimental python3_12.7-final-0

depontius · Advocate Joined: 05 May 2004 Posts: 3525

Is there a way to get LDFLAGS tailored differently for a specific package, kind of like /etc/portage/package.use?

For most software the suggestions in this thread are good, but XOrg seems to think differently. (IIRC they mentioned security concerns) It will build with these flags, but complains every time and makes suggestions, though at the moment the only one I can remember is "-z now". For that matter, XOrg already strips a bunch of CFLAGS, maybe it a package has feelings that strong, they should strip and rework LDFLAGS, too.
_________________
.sigs waste space and bandwidth

wrc1944 · Posted: Thu Mar 10, 2005 6:08 pm Post subject:

Update:
I guess sometimes packages do strip LDFLAGS. I've been using the basic

LDFLAGS="-Wl,-O1"

for about three weeks now. In addition to a few emerge syncs and -upD worlds, I've also done an emerge -e system, and an emerge -e world during this time, with no problems, on two ~x86 systems with gcc-3.4.3-20050110. I've noticed the LDFLAGS showing up in the gcc output of some packages, but not in others.

I've had no issues so far, and no complaints.
_________________
Main box- AsRock x370 Gaming K4
Ryzen 7 3700x, 3.6GHz, 16GB GSkill Flare DDR4 3200mhz
Samsung SATA 1000GB, Radeon HD R7 350 2GB DDR5
OpenRC Gentoo ~amd64 plasma, glibc-2.40-r5, gcc-14
kernel-6.12.8 USE=experimental python3_12.7-final-0

Kyrra · n00b Joined: 15 Jan 2003 Posts: 53 Location: Kansas

I had the same problem with using LDFLAGS to compile Emacs as listed in a post higher in this thread. But everything else I've compiled on my system hasn't had a problem with the LDFLAGS yet.
_________________
It's not what it is, it's something else.
-Kyrra

dalek · Posted: Sun Apr 03, 2005 11:57 pm Post subject:

I was using this but was getting a error about lazy bindings: edit, notice that this line is commented out. :lol:

infirit · Posted: Fri Apr 08, 2005 8:38 pm Post subject:

Another flag that I am looking into lately is -Wl,--as-needed. Some app break horibly but most benefit from it .

It all started with an editorial on osnews.com and this thread is a result of it.
_________________
EASY TO INSTALL = Difficult to install, but instruction manual has pictures.
Join the adopt an unanswered post initiative today

makzu · n00b Joined: 28 Jun 2004 Posts: 42

I'm looking around the man page for ld right now, wondering what else we can add into this. (Yes, I am a ricer, I have to make sure I'm not missing anything) Anyway, there's a few options that I'm a little curious about now, including:

schrepfler · Posted: Tue May 31, 2005 9:31 pm Post subject:

Are there any new tips for the use of LDFLAGS, what are some good configs for the 3.4, 3.4 and 4.0 compilers?