%general-entities; ]> This chapter shows how to build the last missing bits of the temporary system: first, the tools needed by the build machinery of various packages, then three packages needed to run tests. Now that all circular dependencies have been resolved, we can use a chroot environment, completely isolated from the computer used for the build, except for the running kernel. For proper operation of the isolated environment, some communication with the running kernel must be established. This is done through the so-called Virtual Kernel File Systems, which must be mounted when entering the chroot environment. You may want to check that they are mounted by issuing ls $LFS/dev, ls $LFS/proc, or ls $LFS/sys. Note that mounting the virtual kernel file systems must be done each time you want to enter the chroot environment. Until , the commands must be run as root, with the LFS variable set. After entering chroot, all commands are run as root, fortunately without access to the OS of the computer you build LFS on. Be careful anyway, as it is easy to destroy the whole LFS system with badly formed commands.