what does, "export CC=gcc32" do?

[edwardsen35]

I have a Nvidia Video Card and when I installed Fedora I had a problem installing the driver. In /var/log/nvidia-installer.log got the following error message:

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 You appear to be compiling the NVIDIA kernel module with
a compiler different from the one that was used to compile
the running kernel. This may be perfectly fine, but there
are cases where this can lead to unexpected behaviour and
system crashes.

If you know what you are doing and want to override this
check, you can do so by setting IGNORE_CC_MISMATCH.

In any other case, set the CC environment variable to the
name of the compiler that was used to compile the kernel.


Well I went on Nvidia's support forum and I found a post that said to run

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export CC=gcc32

before you install the driver and that worked. When I installed fedora I used gcc version 3.2.3 but I currently have gcc version 3.3.2 installed. My question is, when I ran

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export CC=gcc32

what exactly did that do? Did it tell the computer to use gcc version 3.2.3 from now on when installing programs or just that one time or until I restart the computer?

[Tux]

Until you restart. You have to add the command to a user/system init script for it to stick.

[Void Main]

"export CC=gcc32" sets the "CC" environment variable to "gcc32" which let the build scripts know they should use gcc32 as the compiler rather than gcc. If you notice, gcc32 and gcc are not the same version as you hinted at:

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[voidmain@laplinux voidmain]$ gcc32 --version
gcc32 (GCC) 3.2.3 20030422 (Red Hat Linux 3.2.3-6)
Copyright (C) 2002 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 
[voidmain@laplinux voidmain]$ gcc --version
gcc (GCC) 3.3.2 20031022 (Red Hat Linux 3.3.2-1)
Copyright (C) 2003 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.


Hence gcc32 really means gcc v3.2.x. If you do a "cat /proc/version" you'll notice Fedora's kernel was compiled with gcc version 3.2:

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[voidmain@laplinux voidmain]$ cat /proc/version
Linux version 2.4.22-1.2115.nptl (bhcompile@daffy.perf.redhat.com) (gcc version 3.2.3 20030422 (Red Hat Linux 3.2.3-6)) #1 Wed Oct 29 15:42:51 EST 2003


The same compiler should be used to compile kernel modules as was used to compile the kernel. If not, you can end up with some problems like the ones you have experienced.

Now I haven't tried this but I suppose there is a good chance that if you compile the kernel with gcc v3.3.x and then try and compile your video drivers with the same compiler it *might* work. There very well could be other incompatibilities with the v3.3.x compiler that are causing problems though and might explain why the kernel comes compiled with v3.2.x.

[edwardsen35]

Thanks for the help Void Main and Tux

[Calum]

"export CC=gcc32" sets the "CC" environment variable to "gcc32" which let the build scripts know they should use gcc32 as the compiler rather than gcc. If you notice, gcc32 and gcc are not the same version as you hinted at

finally one i actually know the answer to, and void main gets there first!
never mind, void, i have come to expect it on these forums, there are so many people who know stuff here, i hang around mainly to try and sook it all up by osmosis!