x86 and AMD64 apps question

SAngeli · l33t Joined: 16 Apr 2004 Posts: 904 Location: Italy

Hi,

I have been so far running gentoo on x86. Now, I am about to install gentoo on a AMD64 with native 64-bit OS.
I have some questions about the applications I wish to install.

Usually, when I wish to install an application, I first verify that it is or is not in portage tree and which is its latest stable version. If not found, I hunt the source files and compile it myself.

Questions:
1) If the application is not in portage and the developer posts its executible files (without specifying if it is for x86 or AMD64) so that I can compile and install them, do I have to look for 64-bit code or can I just download the code available and istall it either on the x86 or on the AMD64 reguardless of the OS specs? What is my rule of thumb?

2) Obviously, if I have gentoo AMD64 installed, portage (emerge) will seek and return only for 64-bit applications. Correct? If yes, what if I find an application that is not available for AMD64 but available for x86? What should/could I do?

3) Any other suggestion that would help me better understand how to apporach AMD64 - applications would be appreciated.

Thank you for clearing up my mind,
Spiro

fourhead · Posted: Wed Apr 27, 2005 11:02 pm Post subject:

That's very simple:

An x86 machine can only compile/execute x86 (32bit) software.

An AMD64 machine can both compile/execute x86 and AMD64 software.

When you have a 64bit Gentoo installed the only difference is that whenever you install a program via Portage it will basically download the same sources as it would on an x86 machine, but the software will be compiled in 64bit-mode. If a package won't compile in 64bit-mode yet (as OOo for example) then Portage will either compile it 32bit or you can install a binary package (64/32bit, whatever is available).

To sum it all up: If you have installed Gentoo correctly on an AMD64 with all CFLAGS & USE flags set correctly, you don't have to care about this 32bit/64bit stuff at all, just install your packages as you're used to with Portage.

Tom

SAngeli · l33t Joined: 16 Apr 2004 Posts: 904 Location: Italy

Hi Tom,

thank you for your explanations.

fourhead · Posted: Thu Apr 28, 2005 12:01 am Post subject:

Hi, okay I'll try to answer your questions first:

A) Absolutely correct

B) Portage would not install such a package, but there's a way to still install it, please don't ask me how I've seen it somewhere on the forum but don't know where. You need USE="multilib" for this.

C) Afaik, if you manually compile something, it would be 64bit, but again I'm not entirely sure.

D) You can of course install Gentoo 64bit-only without any 32bit stuff, but it's not a bad idea to have 32bit libs installed. Some packages still don't work 64bit, for ex. OpenOffice or commercial stuff like VMware, Skype etc. Portage should automatically emerge the emul-libs in the case you install an application that is 32bit only.

Finally, here's my relevant settings from /etc/make.conf:

CHOST="x86_64-pc-linux-gnu"
CFLAGS="-march=athlon64 -O2 -pipe" (also CXXFLAGS)
USE="-* alsa arts avi cdr crypt cups divx4linux dv dvd dvdr emul-linux exif gif \
gphoto2 java jpeg kde kdeenablefinal mad mp3 mpeg multilib nptl ogg \
oggvorbis opengl pic png ppds qt qt-mt quicktime samba ssl tiff truetype \
unicode usb X xine xv xvid"

USE of course also depends on your needs. I'm running on ~AMD64, depending on your version of gcc you may need another -march or -mcpu setting, but this is described in make.conf.

I hope this helps you ...

Tom

eean · Posted: Sat Apr 30, 2005 6:54 am Post subject:

I don't understand, I thought you had to have a chrooted Gentoo to install 32-bit apps?