(Solved)Wrong CHOST variable on a fresh install...?

jaydoc · n00b Joined: 04 Jan 2009 Posts: 61 Location: Miami, FL

the desktop on which I am installing Gentoo has an Intel core 2 duo processor. I am installing 32 bit gentoo on it.

the default CHOST values are set to, CHOST="i386-pc-linux-gnu". Shouldn't it be i686...?

CFLAGS="-O2 -mtune=i686 -pipe"
CXXFLAGS="-O2 -mtune=i686 -pipe"

these are the default CFLAGS.

If so, can I change the CHOST variable...? I saw a post in these forums saying that the CHOST variable could not be altered unless one was installing from a stage 1 tarball. IS that so? I went through the handbook that was written about this and it does caution one about some serious problems that could be anticipated, but I have a fresh install, on which I am yet to emerge anything.

yabbadabbadont · Posted: Fri Jan 09, 2009 1:04 am Post subject:

I would guess that you downloaded the wrong stage3 tarball when you did your installation.

jaydoc · n00b Joined: 04 Jan 2009 Posts: 61 Location: Miami, FL

stage3-x86-2008.0.bz2

That was the tarball I used. Isn't that the one for 32 bit x86 systems...?

isilia · Apprentice Joined: 25 Feb 2008 Posts: 177

jaydoc · n00b Joined: 04 Jan 2009 Posts: 61 Location: Miami, FL

That was my mistake then...

Thanks for the quick reply.

NathanZachary · Moderator Joined: 30 Jan 2007 Posts: 2605

Just so you know for future reference, the x86 tarball is there for much older machines. These machines have processors that are based on the Pentium Pro or older.
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zyko · Posted: Fri Jan 09, 2009 3:00 am Post subject:

i386 is a correct identifier for a Core 2 Duo CPU -- i686 would have done as well, but it hopefully won't make a difference.

The CHOST variable in make.conf is passed to the configure script during compilation. Portage uses a wrapper named econf, which is just calling the normal configure script with some Gentoo-specific variables. One of those is --host=${CHOST}. This is mostly needed by the configure script to differentiate between hosts that are actually different, like i386-pc-linux versus sparc-sun-solaris versus mips-*-unknown etc...

On most occasions, configure does not need to differentiate between i386, i486 or higher. Most scripts use something like "i[3456]86-*-linux*" anyway, so they fit for all x86 hosts. There also are other ways to detect the actual host architecture for compile-time configuration.

CHOST should not affect the produced binaries in any significant way. CHOST does not affect optimization, only CFLAGS does that. There is no loss of l33tness because 3 < 6.

Does anybody know of a program that supports i686 but not i386 and that uses the CHOST variable to base this decision on? Does anybody know a program that produces different binaries for i386 versus i686 based on CHOST? I'd guess that >=99% of the Portage tree is not affected by i386 vs i686 in the CHOST variable.

jaydoc · n00b Joined: 04 Jan 2009 Posts: 61 Location: Miami, FL

I did read this on the gentoo docs site, which seems to indicate some difference from the use of 686 vs 386

yabbadabbadont · Posted: Fri Jan 09, 2009 4:25 am Post subject:

Just download the i686 stage file and reinstall your system. Then you won't have to worry about it.

zyko · Posted: Fri Jan 09, 2009 4:30 am Post subject:

You're right, glibc will produce the following message on CHOST="i386-*":

d2_racing · Posted: Fri Jan 09, 2009 3:08 pm Post subject:

Hi, and if you want to use your Core 2 duo in 64 bits mode, then download the AMD64 Stage 3.

Since you have a Core 2 duo, you should go with a 64 bits installation, only to unleash the power of your processor

jaydoc · n00b Joined: 04 Jan 2009 Posts: 61 Location: Miami, FL

I would like to do that, but I was reading about it, and there still seems to be very little difference in speed for my usual uses of the computer, and also, from what I read, there still seems to be a wee bit less support for 64 bit linux, especially in Flash and such multimedia support. I had a bad experience with Ubuntu Ibex 64 bit, in which I could not get flash working at all, even though I tried all I could, which given my lack of computer expertise, was admittedly not much.

I have a more immediate problem... I did an emerge =sys-devel/gcc-4.3.2, to upgrade gcc, so that i could use the march=core2 option instead pf prescott. I did an env-update after that and then I did gcc-config -l

Raniz · Posted: Fri Jan 09, 2009 4:27 pm Post subject:

I'm running a 64bit multilib system and I've had no troubles at all with flash and other 32bit only stuff (like wine and zsnes).
The multilib profile takes care of everything for you, no need to worry and it just works

cyrillic · Posted: Fri Jan 09, 2009 6:25 pm Post subject:

jaydoc · n00b Joined: 04 Jan 2009 Posts: 61 Location: Miami, FL

Yes cyrillic...!

I got direct proof of that..! I tried emerging some packages, and the repeated error was that it could not be compiled... I searched around a bit, and got the idea that this sort of error was due to improper CFLAGS, so I went ahead and changed CFlags back to prescott and they worked.

Saw your post and tried doing what you said, and changed to core2 and there is no error this time when I am (rather, gcc is :wink:

)compiling something. Thanks so much. I get the jitters when I see code running on the screen like it does on The Matrix.. More comfortable with those gaping wounds that I repair sometimes...!

@raniz... I am too much a novice at all this, to be able to troubleshoot something if it turns out wrong, so I prefer to stay with the tried and tested, but one day I will take the plunge into AMD64