So any fixes for that march=pentium4 flag?

Mr. Hahn · Apprentice Joined: 05 Apr 2003 Posts: 250

any? btw, what was that work around method to get the see2 support w/ th pentium4 cflag? I think I remeber it being a combination of mpu=pentium4 & march=pentium3 :?:

Lovechild · Posted: Wed May 14, 2003 7:43 pm Post subject:

GCC 3.3 or -march=pentium3 -mcpu=pentium4 for GCC 3.2.x

Mr. Hahn · Apprentice Joined: 05 Apr 2003 Posts: 250

is the sse2 flag the same w/ the later method? (-msse2)

Lovechild · Posted: Wed May 14, 2003 8:07 pm Post subject:

SPo0n · Posted: Wed May 14, 2003 8:54 pm Post subject:

i always wondered why stuff was compiling with -pentium3

I've got a P4 2.53ghz processor, gcc 3.2.2, shall i leave it as is?

Mr. Hahn · Apprentice Joined: 05 Apr 2003 Posts: 250

Lovechild · Posted: Wed May 14, 2003 10:14 pm Post subject:

Mr. Hahn · Apprentice Joined: 05 Apr 2003 Posts: 250

so I guess an emerge gcc will do the trick , or is there more to it?

RedBeard0531 · Guru Joined: 21 Sep 2002 Posts: 415 Location: maryland

Mr. Hahn · Apprentice Joined: 05 Apr 2003 Posts: 250

Narada · Guru Joined: 12 Dec 2002 Posts: 300 Location: London, UK

Cossins · Posted: Thu May 15, 2003 9:33 pm Post subject:

No, -march does not override -mcpu.
march generates CPU-optimized code, whereas mcpu generates CPU-specific code.

- Simon

Ard Righ · Posted: Fri May 16, 2003 5:34 am Post subject:

/jumps on Soapbox...

Well, the problem nowadays doesn't appear so much to be with the GCC 3.2+ generated code, but more delinquent packages that are not conforming to decent coding standards, and getting killed during a perfectly legitimate (IMO) -march=pentium4 compile.

I tried installing Gnome the other day, it died out on a package called gst-libs. Now I had a look through the code for this gst-lib, and it kept getting killed due to bad maths error, yet the program was set to compile with -mpu=i486 with a -ffast-math!

I have read through a fair number of ebuilds, when looking to install packages. Without going through 100 or so each time I want to install something, it becomes a pain to make sure the people generating this code are doing it properly the first time around, and save the users having to edit them to get fixed.

And it's all well and good editing an ebuild to change USE flags or CFLAGS that are being stripped. But when it's in a header or source file for the program itself, it becomes a problem with evangelising the developers to fix this stuff - and I don't think users can ever bother with such things.

Maybe it's time to start a "Pentium 4 Users Group" to lobby programmers to look into fixing their code up a bit.

splooge · l33t Joined: 30 Aug 2002 Posts: 636

Actually I just built glibc with -march=pentuim4 -mcpu=pentium3 which allowed me to compile the rest of my system with these flags:

CFLAGS="-march=pentium4 -mmmx -msse -msse2 -mfpmath=sse,387 -O3 -pipe -fomit-frame-pointer -funroll-loops -frerun-cse-after-loops -frerun-loop-opt -falign-functions=4 -fschedule-insns2 -fforce-addr -fprefetch-loop-arrays -ffast-math -fexpensive-optimizations"

Everything works great so far. I just compiled KDE overnight and it works beautifully. Using the python script to check for sse errors returns nothing negative.
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Mr. Hahn · Apprentice Joined: 05 Apr 2003 Posts: 250

Mr. Hahn · Apprentice Joined: 05 Apr 2003 Posts: 250

Megaptera · Tux's lil' helper Joined: 29 Jul 2002 Posts: 145

Injecting a stub just means tricking portage into thinking something has been emerged when it hasn't been. Just do:

Mr. Hahn · Apprentice Joined: 05 Apr 2003 Posts: 250

Mr. Hahn · Apprentice Joined: 05 Apr 2003 Posts: 250

ok got it working

!

Mr. Hahn · Apprentice Joined: 05 Apr 2003 Posts: 250

dam it , it did!

I'm into the emerge and I open another console, gcc -v, and it says 3.2.2. Will it still complete the remainder of the system compile using 3.2.3? Will it be bad if I have to emerge 3.2.3 again with the 3.2.2 compiler and the P4 flags? grrrr!

Megaptera · Tux's lil' helper Joined: 29 Jul 2002 Posts: 145

What you could do to get around that is edit the ebuilds (and probably move them to your portage overlay) so that 3.2.2 and 3.2.3 have different slots. This would basically let portage up/downgrade gcc however it wants between the two, because as far as your system is concerned they're sitting in different "slots", and it won't unmerge either of them. I'm going to guess there's a better solution, though.

I've been looking at the gcc changelogs for my own machine and I haven't seen anything that says 3.2.3 fixes the p4 bug -- on the gcc website , the changelog for 3.3 says

Mr. Hahn · Apprentice Joined: 05 Apr 2003 Posts: 250

yeah, but I thought 3.3 is still kinda buggy, I should be keeping up w/ it though, but im not. It is going to be a pain getting this system the way I want it anyways. I'm planning on getting a scsi drive and controller, so basically im gonna be installing it all over again one of these days, but hey I have all summer until school starts and I start programming on this box

.

Megaptera · Tux's lil' helper Joined: 29 Jul 2002 Posts: 145

My understanding of 3.3 is that it's stricter than 3.2 when it comes to what it considers workable code. There are programs out there that won't compile with it, but -- and this comes with the big caveat that I'm not the most knowledgeable of people to be saying this -- as different programs clean themselves up to work with 3.3, we'll be getting more tightly-coded stuff. I've been using 3.3 for a couple of days without problems. Of course, hehe, if you're gonna be reinstalling anyway ...
Well, with luck it'll be unmasked soon. :)
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Mr. Hahn · Apprentice Joined: 05 Apr 2003 Posts: 250

with luck it'll be the default compiler when I reinstall, and I can have the sse2 action going! I swear , Athlon MPs are best for this os,not P4s