Trouble installing gfortran

[Jonathan Wakely]

On 11 January 2012 22:11, John Harper wrote:
> On Tue, 10 Jan 2012, Jonathan Wakely wrote:
>
> One question I have is that our systems people
> installed gfortran 4.4.4 and when I use it with -v I get inter alia
> Target: i386-redhat-linux6E
> but when I installed gfortran 4.6.2 myself on the same machine without
> specifying --target I get
> Target: i686-pc-linux-gnu
>
> Why the difference? FWIW the command   set | grep 86   gives
> HOSTTYPE=i386
> MACH=i386
> MACHTYPE=i386-redhat-linux-gnu

See http://airs.com/ian/configure/configure_4.html for info on
configuration triplets.  The differences would be more significant if
you were looking at an x86 GNU/Linux machine and e.g.
sparc64-sun-solaris2.10, but for two different triplets for an x86
there isn't a lot of difference.

The "pc" versus "redhat" manufacturer field is not usually used, it's
just descriptive.

Since GCC 4.5 the default instruction set generated by GCC on x86
depends on the machine type it is configured for, so for the GCC 4.4
installation the "i386" is merely descriptive, and of "i386", "i486",
"pentium2" etc would have been equivalent, but for GCC 4.6 it means
that GCC will generate code that assumes it will run on an i686 (or
later).  See http://gcc.gnu.org/onlinedocs/gcc/i386-and-x86_002d64-Options.html
for details of how to override the default machine type with -march
option.

I don't think "linux6E" vs "linux-gnu" matters either, I think
configure scripts match on linux*