cvs commit: hints lowspace.txt

timothy at linuxfromscratch.org timothy at linuxfromscratch.org
Sat Sep 28 09:25:34 PDT 2002


timothy     02/09/28 09:25:34

  Added:       .        lowspace.txt
  Log:
  Initial commit.
  
  Revision  Changes    Path
  1.1                  hints/lowspace.txt
  
  Index: lowspace.txt
  ===================================================================
  TITLE:		LFS for small hard drives
  LFS VERSION:	4.0
  AUTHOR:		James Smaby <jsmaby at virgo.umeche.maine.edu>
  
  SYNOPSIS:
  	The recommended LFS partition size is 1GB.  By following
  	this hint, that number can be 300MB, and possibly lower.
  	So if you're on a 486, or want to compile LFS in RAM,
  	this hint is for you.
  
  HINT:
      Much more space is needed to build LFS than is needed for the
  final system.  There used to be a general rule that once you're past
  glibc, you're all set, but now gcc-3 is a similarly high hurdle.
  Note that gcc-2.95.3-2, used in LFS-3.3, is smaller, and in some
  people's opinions, better than gcc-3, and using it might be a good
  idea for people low on disk space.  You'll need about 300MB of disk
  space available to LFS, less if you use gcc-2 and don't install
  the locales.  The disk space doesn't all have to be physical.  You can
  stick some things on a tmpfs if you have spare RAM, or just really
  need the space.  Indeed, you can build an LFS entirely in RAM if
  you have more than about 350MB, using:
    mount tmpfs -t tmpfs -o size=300m $LFS
  You can also save quite a bit of space if the sources for glibc
  and glibc are already unpacked and on a cdrom.
  
      First off, the default compiler options of "-O2 -g" make large
  binaries/object files.  Assuming you won't need debugging information
  in the system's executables/libraries, the following environment
  variables should be set (these are conservative; -march=i686 will
  help, but might break glibc/gcc/binutils).
    export CC="gcc -s"
    export CFLAGS="-Os -fomit-frame-pointer -s"
    export BOOT_CFLAGS="$CFLAGS"
  
       For chapter 5, build gcc-3 first, as it's the biggest package.
  Depending on available space, you may want to delete some of the
  unused sources first:
    rm -rf libjava libobjc gcc/ada gcc/f gcc/java gcc/objc
  Using make bootstrap uses extra space, and if you have a trustworthy
  compiler on your host, bootstrap is unneeded.
  
       After completing chapter 5, make a minimal static by running
  these commands:
    mkdir -p $LFS/minimal/bin
    mkdir -p `echo $LFS/static/lib/gcc-lib/*/*/include | sed s/static/minimal/`
    # Copy over only the files used by building a chapter 6.
    # These were found using find -anewer
    cp -a $LFS/static/bin/{ar,as,awk,basename,bash,bzip2,cat,cc,chmod,\
      chown,cmp,cp,cpp,cut,date,diff,dirname,du,echo,egrep,env,expr,fgrep,\
      find,fold,gawk,gcc,grep,gunzip,gzip,head,hostname,install,install-info,\
      ld,ln,ls,make,makeinfo,mkdir,mknod,mount,mv,nl,nm,objdump,od,pwd,\
      ranlib,readelf,rm,rmdir,sed,sleep,sort,strip,tail,tar,touch,tr,true,\
      uname,uniq,wc,whoami,xargs,zcat} $LFS/minimal/bin
    cp -a $LFS/static/lib/gcc-lib/*/*/{cc1,collect2,cpp0,crtbegin.o,crtbeginS.o,\
      crtbeginT.o,crtend.o,crtendS.o,libgcc.a,specs} $LFS/minimal/lib/*/*/*
    cp -a $LFS/static/lib/gcc-lib/*/*/include/{float.h,limits.h,stdarg.h,
      stdbool.h,stddef.h,stdio.h,syslimits.h} $LFS/minimal/lib/*/*/*/include
    # Strip any unneeded symbols from binaries
    strip $LFS/minimal/bin/* $LFS/minimal/lib/*/*/*/{cc1,collect2,cpp0}
    # Strip debugging symbols from object files
    strip -g $LFS/minimal/lib/*/*/*/*.*
    # Use bash builtins for some commands
    echo -e '#!/bin/bash\n echo $@' > $LFS/minimal/bin/echo
    echo -e '#!/bin/bash\n pwd' > $LFS/minimal/bin/pwd
    echo -e '#!/bin/bash\n sleep $@' > $LFS/minimal/bin/sleep
    echo -e '#!/bin/bash\n' > $LFS/minimal/bin/true
    echo -e '#!/bin/bash\n echo root' > $LFS/minimal/bin/whoami
  If all goes well, "du -sh $LFS/minimal" should produce 35M.  That's all
  you need of a chapter 5 to build a chapter 6.  Replace the old static:
    rm -rf $LFS/static
    mv $LFS/minimal $LFS/static
  
  After entering chroot, you lose your environment variables.  Reset
  them here:
    export CC="gcc -s"
    export CFLAGS="-Os -fomit-frame-pointer -s"
    export CXXFLAGS="$CFLAGS"
    export BOOT_CFLAGS="$CFLAGS"
  
  On to the first hurdle, glibc.  Really the only thing you can do
  that I've found is add "--enable-omitfp --enable-kernel=2.4.19" to
  the configure line.  After it's built, you should be getting awfully
  close to 300MB.  Relieve a little stress by killing libc_g.a:
    echo -n > libc_g.a
  We don't care about debugging, so this (25MB!) file isn't needed.
  Now "make install" should have room.  Run the following commands
  to free up even more:
    strip /{usr/,}{lib/*so,sbin/*,bin/*}
    strip -g /usr/lib/*.a
    rm /usr/lib/*_g.a
    bzip2 /usr/share/info/*info*
  If you really, _really_ need them, you can install the locales, but
  they eat up precious space.
  
      Okay, onto gcc.  If you're using gcc-2, then you're fine, and can
  just go on to do the rest of the LFS.  We'll need some tweaking for gcc-3.
  Note that installing man-pages is preferably done after gcc to save
  about 6MB for the gcc build.  First, delete some of the bigger unneeded
  source directories:
    rm -rf libjava libobjc gcc/ada gcc/f gcc/java gcc/objc
  There won't be enough room (to stay under 300MB) to do a bootstrap compile,
  so just type "make".  This has the advantage that it takes quite a bit
  less time to compile :-)  You may need to do some preliminary stripping
  before installing:
    strip gcc/{cc1,cc1plus}
    find . -name *.so -exec strip {} \;
  
      Things may start getting a little tight when building perl; compressing
  the man and info pages should be enough to make room:
    bzip2 -d /usr/share/info/*.bz2
    bzip2 /usr/share/info/*info*
    bzip2 /usr/share/man/man?/*.?
  
      Now you can get busy stripping down your fresh LFS to make room for
  more programs/data.
  
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