HOWTO Restoring Removed Key System Packages

From Gentoo Linux Wiki

This guide is written around glibc. The method works for gcc and any other 'showstopper' packages glibc downgrades are not supported. You need a glibc-2.6 tarball from someone you trust if you cannot build one.

Given 10G of free space you can build your own. This is essentially a gentoo stage 3 install into a file.

Boot a liveCD and mount a partition with >10G free space at /mnt/gentoo Make a 10G empty file

dd if=/dev/zero of=/mnt/gentoo/recovery.file count=2500000 bs=4096

Make a filesystem in the file

mke2fs /mnt/gentoo/recovery.file

a journal is wasted. Make a new mount point

mkdir /mnt/fixme

and mount your new filesystem there

mount -o loop -t ext2 /mnt/gentoo/recovery.file /mnt/fixme

untar a stage 3 tarball into /mnt/fixme Do *not* trash your system by untaring to /mnt/gentoo then mount the fake filesystems

mount -t proc none /mnt/fixme/proc
mount -o bind /dev /mnt/fixme/dev

Do not fetch a portage snapshot. Instead, bind mount your real /usr/portage to /mnt/fixme/usr/portage

mount -o bind /mnt/gentoo/usr/portage /mnt/fixme/usr/portage

Continue into the chroot

chroot /mnt/fixme /bin/bash

.... just like the install

env-update
source /etc/profile
export PS1="(Do not remove glibc) $PS1"

Now you have a working chroot in a file, continue with

emerge glibc
quickpkg glibc

As you used your own distfiles and portage tree, everything should be available and the glibc binary tarball will be deposted in your own /usr/portage/packages/All, outside the chroot. Untar this glibc to /mnt/gentoo and reboot to test. You can remove recovery.file when its done what you needed.