How to set parameter i486 on glibc compiling process of x86_64 system?

Question

My host:

  lfs@sam:/mnt/lfs/sources/glibc-build$ uname -m
  x86_64
  lfs@sam:/mnt/lfs/sources/glibc-build$ 

In lfs(LFS-BOOK-6.8-HTML/chapter05/glibc.html) It says

  case `uname -m` in
    i?86) echo "CFLAGS += -march=i486 -mtune=native" > configparms ;;
  esac

What I should change on 'i?86'?

And should I change 'i486'?

Thank you~

Answer 1

That segment is for if you were building a script to compile glibc automatically in order to run it on this system. The "i?86" is a pattern; if the outut of uname -m matches it, it will run the following commands until it gets to ;;.

You probably don't need it; it was specifically meant to figure out if your architecture type was i386 since glibc doesn't support it anymore.

If you're building it in order to run it on a different system that is not x86_64 (or to run it on this system, but using only 32-bit instructions), then you want to force compiling for i486. You can get rid the case structure completely by converting

case `uname -m` in
  i?86) echo "CFLAGS += -march=i486 -mtune=native" > configparms ;;
esac

to

echo "CFLAGS += -march=i486 -mtune=native" > configparms