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%sccs.include.redist.roff%
@(#)3.t 6.10 (Berkeley) 07/09/93
Upgrading a \*(Ps System
This section describes the procedure for upgrading a \*(Ps system to \*(4B. This procedure may vary according to the version of the system running before conversion. If you are converting from a System V system, some of this section will still apply (in particular, the filesystem conversion). However, many of the system configuration files are different, and the executable file formats are completely incompatible. Installation overview
If you are running \*(Ps, upgrading your system involves replacing your kernel and system utilities. In general, there are three possible ways to install a new \*(Bs distribution: (1) boot directly from the distribution tape, use it to load new binaries onto empty disks, and then merge or restore any existing configuration files and filesystems; (2) use an existing \*(Ps or later system to extract the root and
n /usr filesystems from the distribution tape, boot from the new system, then merge or restore existing configuration files and filesystems; or (3) extract the sources from the distribution tape onto an existing system, and use that system to cross-compile and install \*(4B. For this release, the second alternative is strongly advised if at all possible, with the third alternative reserved as a last resort. In general, older binaries will continue to run under \*(4B, but there are many exceptions that are on the critical path for getting the system running. Ideally, the new system binaries (root and
n /usr filesystems) should be installed on spare disk partitions, then site-specific files should be merged into them. Once the new system is up and fully merged, the previous root and
n /usr filesystems can be reused. Other existing filesystems can be retained and used, except that (as usual) the new .Xr fsck should be run before they are mounted.
It is STRONGLY advised that you make full dumps of each filesystem before beginning, especially any that you intend to modify in place during the merge. It is also desirable to run filesystem checks of all filesystems to be converted to \*(4B before shutting down. This is an excellent time to review your disk configuration for possible tuning of the layout. Most systems will need to provide a new filesystem for system use mounted on
n /var (see below). However, the
n /tmp filesystem can be an MFS virtual-memory-resident filesystem, potentially freeing an existing disk partition. (Additional swap space may be desirable as a consequence.) See .Xr mfs (8).
The recommended installation procedure includes the following steps. The order of these steps will probably vary according to local needs.
n /usr filesystems from the distribution tapes.
n /var filesystem (see .Xr mtree (8)).
n /etc and
n /etc directory. Note that many file formats and contents have changed; see section 3.4 of this document.
n /usr/lib , and other locations into
n /var .
Section 3.2 lists the files to be saved as part of the conversion process. Section 3.3 describes the bootstrap process. Section 3.4 discusses the merger of the saved files back into the new system. Section 3.5 provides general hints on possible problems to be aware of when converting from \*(Ps to \*(4B. Files to save
The following list enumerates the standard set of files you will want to save and suggests directories in which site-specific files should be present. This list will likely be augmented with non-standard files you have added to your system. If you do not have enough space to create parallel filesystems, you should create a .Xr tar image of the following files before the new filesystems are created. The rest of this subsection describes where theses files have moved and how they have changed.
| /.cshrc \(dg root csh startup script (moves to /root/.cshrc) |
| /.login \(dg root csh login script (moves to /root/.login) |
| /.profile \(dg root sh startup script (moves to /root/.profile) |
| /.rhosts \(dg for trusted machines and users (moves to /root/.rhosts) |
| /etc/disktab \(dd in case you changed disk partition sizes |
| /etc/fstab * disk configuration data |
| /etc/ftpusers \(dg for local additions |
| /etc/gettytab \(dd getty database |
| /etc/group * group data base |
| /etc/hosts \(dg for local host information |
| /etc/hosts.equiv \(dg for local host equivalence information |
| /etc/inetd.conf * Internet services configuration data |
| /etc/networks \(dg for local network information |
| /etc/passwd * user data base |
| /etc/printcap * line printer database |
| /etc/protocols \(dd in case you added any local protocols |
| /etc/rc * for any local additions |
| /etc/rc.local * site specific system startup commands |
| /etc/remote \(dg auto-dialer configuration |
| /etc/services \(dd for local additions |
| /etc/syslog.conf * system logger configuration |
| /etc/securettys * merged into ttys |
| /etc/ttys * terminal line configuration data |
| /etc/ttytype * merged into ttys |
| /etc/termcap \(dd for any local entries that may have been added |
| /lib \(dd for any locally developed language processors |
| /usr/dict/* \(dd for local additions to words and papers |
| /usr/include/* \(dd for local additions |
| /usr/lib/aliases * mail forwarding data base (moves to /etc/aliases) |
| /usr/lib/crontab * cron daemon data base (moves to /etc/crontab) |
| /usr/lib/lib*.a \(dg for locally libraries |
| /usr/lib/sendmail.cf * sendmail configuration (moves to /etc/sendmail.cf) |
| /usr/lib/tmac/* \(dd for locally developed troff/nroff macros (moves to /usr/share/tmac/*) |
| /usr/lib/uucp/* \(dg for local uucp configuration files |
| /usr/man/manl * for manual pages for locally developed programs (moves to /usr/local/man) |
| /usr/spool/* \(dg for current mail, news, uucp files, etc. (moves to /var/spool) |
| /usr/src/local \(dg for source for locally developed programs |
| /sys/conf/HOST \(dg configuration file for your machine (moves to /sys/<arch>/conf) |
| /sys/conf/files.HOST \(dg list of special files in your kernel (moves to /sys/<arch>/conf) |
| /*/quotas * filesystem quota files (moves to /*/quotas.user) |
The next step is to build a working \*(4B system. This can be done by following the steps in section 2 of this document for extracting the root and
n /usr filesystems from the distribution tape onto unused disk partitions. For the SPARC, the root filesystem dump on the tape could also be extracted directly. For the HP300 and DecStation, the raw disk image can be copied into an unused partition and this partition can then be dumped to create an image that can be restored. The exact procedure chosen will depend on the disk configuration and the number of suitable disk partitions that may be used. It is also desirable to run filesystem checks of all filesystems to be converted to \*(4B before shutting down. In any case, this is an excellent time to review your disk configuration for possible tuning of the layout. Section 4.2 and .Xr config (8) are required reading.
The \*(4B bootstrap routines pass the identity of the boot device through to the kernel. The kernel then uses that device as its root filesystem. Thus, for example, if you boot from
n /dev/\*(Dk1a , the kernel will use
n \*(Dk1a as its root filesystem. If
n /dev/\*(Dk1b is configured as a swap partition, it will be used as the initial swap area, otherwise the normal primary swap area (\c
n /dev/\*(Dk0b ) will be used. The \*(4B bootstrap is backward compatible with \*(Ps, so you can replace your old bootstrap if you use it to boot your first \*(4B kernel.
Once you have extracted the \*(4B system and booted from it, you will have to build a kernel customized for your configuration. If you have any local device drivers, they will have to be incorporated into the new kernel. See section 4.1.3 and ``Building 4.3BSD UNIX Systems with Config'' (SMM:2).
If converting from \*(Ps, your old filesystems should be converted. If you've modified the partition sizes from the original \*(Ps ones, and are not already using the \*(4B disk labels, you will have to modify the default disk partion tables in the kernel. Make the necessary table changes and boot your custom kernel BEFORE trying to access any of your old filesystems! After doing this, if necessary, the remaining filesystems may be converted in place by running the \*(4B version of .Xr fsck (8) on each filesystem and allowing it to make the necessary corrections. The new version of .Xr fsck is more strict about the size of directories than the version supplied with \*(Ps. Thus the first time that it is run on a \*(Ps filesystem, it will produce messages of the form: DIRECTORY ...: LENGTH xx NOT MULTIPLE OF 512 (ADJUSTED) Length ``xx'' will be the size of the directory; it will be expanded to the next multiple of 512 bytes. The new .Xr fsck will also set default interleave and npsect (number of physical sectors per track) values on older filesystems, in which these fields were unused spares; this correction will produce messages of the form: IMPOSSIBLE INTERLEAVE=0 IN SUPERBLOCK (SET TO DEFAULT)* IMPOSSIBLE NPSECT=0 IN SUPERBLOCK (SET TO DEFAULT) .FS * The defaults are to set interleave to 1 and npsect to nsect. This is correct on most drives; it affects only performance (and in most cases, virtually unmeasurably). .FE Filesystems that have had their interleave and npsect values set will be diagnosed by the old .Xr fsck as having a bad superblock; the old .Xr fsck will run only if given an alternate superblock (fsck -b32), in which case it will re-zero these fields. The \*(4B kernel will internally set these fields to their defaults if fsck has not done so; again, the -b32 option may be necessary for running the old .Xr fsck .
In addition, \*(4B removes several limits on filesystem sizes that were present in \*(Ps. The limited filesystems continue to work in \*(4B, but should be converted as soon as it is convenient by running .Xr fsck with the -c 2 option. The sequence fsck -p -c 2 will update all of them, fix the interleave and npsect fields, fix any incorrect directory lengths, expand maximum uid's and gid's to 32-bits, place symbolic links less than 60 bytes into their inode, and fill in directory type fields all at once. The new filesystem formats are incompatible with older systems. If you wish to continue using these filesystems with the older systems you should make only the compatible changes using fsck -c 1. Merging your files from \*(Ps into \*(4B
When your system is booting reliably and you have the \*(4B root and
n /usr filesystems fully installed you will be ready to continue with the next step in the conversion process, merging your old files into the new system.
If you saved the files on a .Xr tar tape, extract them into a scratch directory, say
n /usr/convert : # mkdir /usr/convert # cd /usr/convert # tar xp
The data files marked in the previous table with a dagger (\(dg) may be used without change from the previous system. Those data files marked with a double dagger (\(dd) have syntax changes or substantial enhancements. You should start with the \*(4B version and carefully integrate any local changes into the new file. Usually these local modifications can be incorporated without conflict into the new file; some exceptions are noted below. The files marked with an asterisk (*) require particular attention and are discussed below.
The most immediately obvious change in \*(4B is the reorganization of the system filesystems. Users of certain recent vendor releases have seen this general organization, although \*(4B takes the reorganization a bit further. The directories most affected are
n /etc , which now contains only system configuration files;
n /var , a new filesystem containing per-system spool and log files; and
n /usr/share, which contains most of the text files shareable across architectures such as documentation and macros. System administration programs formerly in
n /etc are now found in
n /sbin and
n /usr/sbin . Various programs and data files formerly in
n /usr/libdata , respectively. Administrative files formerly in
n /var/account and, similarly, log files are now in
n /usr/ucb has been merged into
n /usr/bin , and the sources for programs in
n /usr/src/usr.bin . Other source directories parallel the destination directories;
n /usr/src/etc has been greatly expanded, and
n /usr/src/share is new. The source for the manual pages, in general, are with the source code for the applications they document. Manual pages not closely corresponding to an application program are found in
n /usr/src/share/man . The locations of all man pages is listed in
n /usr/src/share/man/man0/man[1-8] . The manual page .Xr hier (7) has been updated and made more detailed; it is included in the printed documentation. You should review it to familiarize yourself with the new layout.
A new utility, .Xr mtree (8), is provided to build and check filesystem hierarchies with the proper contents, owners and permissions. Scripts are provided in
n /usr/src/etc/mtree ) for the root,
n /usr and
n /var filesystems. Once a filesystem has been made for
n /var , .Xr mtree should be used to create a directory hierarchy there. Changes in the
n /etc filesystem
The
n /etc directory now contains nearly all of the host-specific configuration files. Note that some file formats have changed, and those configuration files containing pathnames are nearly all affected by the reorganization. See the examples provided in
n /etc (installed from
n /usr/src/etc ) as a guide. The following table lists some of the local configuration files whose locations and/or contents have changed. I .3i
| 4.3BSD and Earlier \*(4B Comments |
| _ _ _ |
| /etc/fstab /etc/fstab new format; see below |
| /etc/inetd.conf /etc/inetd.conf pathnames of executables changed |
| /etc/printcap /etc/printcap pathnames changed |
| /etc/syslog.conf /etc/syslog.conf pathnames of log files changed |
| /etc/ttys /etc/ttys pathnames of executables changed |
| /etc/passwd /etc/master.passwd new format; see below |
| /usr/lib/sendmail.cf /etc/sendmail.cf changed pathnames |
| /usr/lib/aliases /etc/aliases may contain changed pathnames |
| /etc/*.pid /var/run/*.pid |
| .T& |
| l l l |
| lfC lfC l. |
| New in 4.3BSD-Tahoe \*(4B Comments |
| _ _ _ |
| /usr/games/dm.config /etc/dm.conf configuration for games (see dm\|(8)) |
| /etc/zoneinfo/localtime /etc/localtime timezone configuration |
| /etc/zoneinfo /usr/share/zoneinfo timezone configuration |
| New in \*(4B Comments |
| _ _ _ |
| /etc/man.conf lists directories searched by man\|(1) |
| /etc/kerberosIV Kerberos directory; see below |
System security changes require adding several new ``well-known'' groups to
n /etc/group . The groups that are needed by the system as distributed are:
| name number purpose |
| wheel 0 users allowed superuser privilege |
| daemon 1 processes that need less than wheel privilege |
| kmem 2 read access to kernel memory |
| sys 3 access to kernel sources |
| tty 4 access to terminals |
| operator 5 read access to raw disks |
| bin 7 group for system binaries |
| news 8 group for news |
| wsrc 9 write access to sources |
| games 13 access to games |
| staff 20 system staff |
| guest 31 system guests |
| nobody 39 the least privileged group |
| utmp 45 access to utmp files |
| dialer 117 access to remote ports and dialers |
n /var/spool now run set-group-id to ``daemon'' so that users cannot directly access the files in the spool directories. The special files that access kernel memory,
n /dev/mem , are made readable only by group ``kmem''. Standard system programs that require this access are made set-group-id to that group. The group ``sys'' is intended to control access to kernel sources, and other sources belong to group ``wsrc.'' Rather than make user's terminals writable by all users, they are now placed in group ``tty'' and made only group writable. Programs that should legitimately have access to write on user's terminals such as .Xr talkd and .Xr write now run set-group-id to ``tty''. The ``operator'' group controls access to disks. By default, disks are readable by group ``operator'', so that programs such as .Xr dump can access the filesystem information without being set-user-id to ``root''. The .Xr shutdown (8) program is executable only by group operator and is setuid to root so that members of group operator may shut down the system without root access.
The ownership and modes of some directories have changed. The .Xr at programs now run set-user-id ``root'' instead of ``daemon.'' Also, the uucp directory no longer needs to be publicly writable, as .Xr tip reverts to privileged status to remove its lock files. After copying your version of
n /var/spool , you should do: # chown -R root /var/spool/at # chown -R uucp.daemon /var/spool/uucp # chmod -R o-w /var/spool/uucp
The format of the cron table,
n /etc/crontab , has been changed to specify the user-id that should be used to run a process. The userid ``nobody'' is frequently useful for non-privileged programs. Local modification are now put in a separate file,
n /etc/crontab.local .
Some of the commands previously in
n /etc/rc.local have been moved to
n /etc/rc ; several new functions are now handled by
n /etc/rc.local . You should look closely at the prototype version of these files and read the manual pages for the commands contained in it before trying to merge your local copy. Note in particular that .Xr ifconfig has had many changes, and that host names are now fully specified as domain-style names (e.g., vangogh.CS.Berkeley.EDU) for the benefit of the name server.
The C-library and system binaries on the distribution tape are compiled with new versions of .Xr gethostbyname and .Xr gethostbyaddr which use the name server, .Xr named (8). If you have only a small network and are not connected to a large network, you can use the distributed library routines without any problems; they use a linear scan of the host table
n /etc/hosts if the name server is not running. If you are on the Internet or have a large local network, it is recommend that you set up and use the name server. For instructions on how to set up the necessary configuration files, refer to ``Name Server Operations Guide for BIND'' (SMM:10). Several programs rely on the host name returned by .Xr gethostname to determine the local domain name.
If you are using the name server, your .Xr sendmail configuration file will need some updates to accommodate it. See the ``Sendmail Installation and Operation Guide'' (SMM:8) and the sample .Xr sendmail configuration files in
n /usr/src/usr.sbin/sendmail/cf . The aliases file,
n /etc/aliases has also been changed to add certain well-known addresses. Shadow password files
The password file format adds change and expiration fields and its location has changed to protect the encrypted passwords stored there. The actual password file is now stored in
n /etc/master.passwd . The hashed dbm password files do not contain encrypted passwords, but contain the file offset to the entry with the password in
n /etc/master.passwd (which is readable only by root). Thus, the .Fn getpwnam and .Fn getpwuid functions will no longer return an encrypted password string to non-root callers. An old-style passwd file is created in
n /etc/passwd by the .Xr vipw (8) and .Xr pwd_mkdb (8) programs. See also .Xr passwd (5).
Several new users have also been added to the group of ``well-known'' users in
n /etc/passwd . The current list is:
| name number |
| root 0 |
| daemon 1 |
| operator 2 |
| bin 3 |
| games 7 |
| uucp 66 |
| nobody 32767 |
After installing your updated password file, you must run .Xr pwd_mkdb (8) to create the password database. Note that .Xr pwd_mkdb (8) is run whenever .Xr vipw (8) is run. The
n /var filesystem
The spooling directories saved on tape may be restored in their eventual resting places without too much concern. Be sure to use the `-p' option to .Xr tar (1) so that files are recreated with the same file modes. The following commands provide a guide for copying spool and log files from an existing system into a new
n /var filesystem. At least the following directories should already exist on
n /var :
n output ,
n log ,
n backups and
n db .
SRC=/oldroot/usr cd $SRC; tar cf - msgs preserve | (cd /var && tar xpf -) # copy $SRC/spool to /var cd $SRC/spool tar cf - at mail rwho | (cd /var && tar xpf -) tar cf - ftp mqueue news secretmail uucp uucppublic | \e (cd /var/spool && tar xpf -) # everything else in spool is probably a printer area mkdir .save mv at ftp mail mqueue rwho secretmail uucp uucppublic .save tar cf - * | (cd /var/spool/output && tar xpf -) mv .save/* . rmdir .save cd /var/spool/mqueue mv syslog.7 /var/log/maillog.7 mv syslog.6 /var/log/maillog.6 mv syslog.5 /var/log/maillog.5 mv syslog.4 /var/log/maillog.4 mv syslog.3 /var/log/maillog.3 mv syslog.2 /var/log/maillog.2 mv syslog.1 /var/log/maillog.1 mv syslog.0 /var/log/maillog.0 mv syslog /var/log/maillog # move $SRC/adm to /var cd $SRC/adm tar cf - . | (cd /var/account && tar xpf -) cd /var/account rm -f msgbuf mv messages messages.[0-9] ../log mv wtmp wtmp.[0-9] ../log mv lastlog ../log Block devices and the root filesystem
The buffer cache in the kernel is now organized as a file block cache rather than a device block cache. As a consequence, cached blocks from a file and from the corresponding block device would no longer be kept consistent. The block device thus has little remaining value. Three changes have been made for these reasons: (1) block devices may not be opened while they are mounted, and may not be mounted while open, so that the two versions of cached file blocks cannot be created, (2) filesystem checks of the root now use the raw device to access the root filesystem, and (3) the root filesystem is initially mounted read-only so that nothing can be written back to disk during or after modification of the raw filesystem by .Xr fsck . The root filesystem may be made writable while in single-user mode with the command .Li "mount -u /" . The mount command has an option to update the flags on a mounted filesystem, including the ability to upgrade a filesystem from read-only to read-write or downgrade it from read-write to read-only. Kerberos
The Kerberos authentication server from MIT (version 4) is included in this release. See .Xr kerberos (1) for a general, if MIT-specific, introduction. If it is configured, .Xr login (1), .Xr passwd (1), .Xr rlogin (1) and .Xr rsh (1) will all begin to use it automatically. The file
n /etc/kerberosIV/README describes the configuration. Each system needs the file
n /etc/kerberosIV/krb.conf to set its realm and local servers, and a private key stored in
n /etc/kerberosIV/srvtab (see .Xr ext_srvtab (8)). The Kerberos server should be set up on a single, physically secure, server machine. Users and hosts may be added to the server database manually with .Xr kdb_edit (8), or users on authorized hosts can add themselves and a Kerberos password upon verification of their ``local'' (passwd-file) password using the .Xr register (1) program.
Note that by default the password-changing program .Xr passwd (1) changes the Kerberos password, which must exist. The .Li -l option to .Xr passwd (1) changes the ``local'' password if one exists.
Note that Version 5 of Kerberos will be released soon, and that Version 4 should probably be replaced at that time. Make and Makefiles
This release uses a completely new version of the .Xr make program derived from the .Xr pmake program developed by the Sprite project at Berkeley. It supports existing makefiles, although certain incorrect makefiles may fail. The makefiles for the \*(4B sources make extensive use of the new facilities, especially conditionals and file inclusion, and are thus completely incompatible with older versions of .Xr make (but nearly all of the makefiles are now trivial!). The standard include files for .Xr make are in
n /usr/share/mk . There is a bsd.README file in
Another global change supported by the new .Xr make is designed to allow multiple architectures to share a copy of the sources. If a subdirectory named
n obj is present in the current directory, .Xr make descends into that directory and creates all object and other files there. We use this by building a directory hierarchy in
n /usr/src . We then create the
n obj subdirectories in
n /usr/src as symbolic links to the corresponding directories in
n /var/obj . (Both of these steps are automated; the makefile in the
n /usr/src directory has an example of a target (``shadow'') which builds the object filesystem, and ``make obj'' in a directory including the standard \*(Bs rules in its Makefile makes the
n obj links in the current directory and recursively in the normal subdirectories.) We have one
n /var/obj hierarchy on the local system, and another on each system that shares the source filesystem. Additions and changes to filesystems
Network filesystem access is available in \*(4B. An implementation of the Network File System (NFS) was contributed by Rick Macklem of the University of Guelph. Its use will be fairly familiar to users of other implementations of NFS. See the manual pages .Xr mount (8), .Xr mountd (8), .Xr fstab (5), .Xr exports (5), .Xr netgroup (5), .Xr nfsd (8), .Xr nfsiod (8), and .Xr nfssvc (8). The format of
n /etc/fstab has changed from previous \*(Bs releases to a blank-separated format to allow colons in pathnames.
An implementation of an auto-mounter daemon, .Xr amd , was contributed by Jan-Simon Pendry of the Imperial College of Science, Technology & Medicine. See the document ``AMD - The 4.4BSD Automounter'' (SMM:13) for further information.
The directory
n /dev/fd contains special files
n 0 through
n 63 which, when opened, duplicate the corresponding file descriptor. The names
n /dev/stderr refer to file descriptors 0, 1 and 2. See .Xr fd (4) and .Xr mount_fdesc (8) for more information.
The system now supports stackable filesystems; this feature allows various filesystems to be stacked on top of each other to provide additive sets of semantics. For example, the umap filesystem (see .Xr mount_umap (8)) is used to mount a sub-tree of an existing filesystem that uses a different set of uids and gids than the local system. Such a filesystem could be mounted from a remote site via NFS or it could be a filesystem on removable media brought from some foreign location that uses a different password file.
Other new filesystems include the loopback filesystem .Xr mount_lofs (8), the kernel filesystem .Xr mount_kernfs (8), and the portal filesystem .Xr mount_portal (8). POSIX changes
The \*(4B system uses the IEEE P1003.1 (POSIX.1) terminal interface rather than the previous \*(Bs terminal interface. The new interface has nearly all of the functionality of the old interface, extending the POSIX interface as necessary. Both the old .Xr ioctl calls and old options to .Xr stty (1) are emulated. This emulation is expected to be unavailable in many vendors releases, so conversion to the new interface is encouraged.
The POSIX.1 job control interface is implemented in \*(4B. A new system call, .Fn setsid , is used to create a job-control session consisting of a single process group with one member, the caller, which becomes a session leader. Only a session leader may acquire a controlling terminal. This is done explicitly via a .Sm TIOCSCTTY .Fn ioctl call, not implicitly by an .Fn open call. The call fails if the terminal is in use. Programs that allocate controlling terminals (or pseudo-terminals) require modification to work in this environment. The versions of .Xr xterm provided in the X11R5 release includes the necessary changes. New library routines are available for allocating and initializing pseudo-terminals and other terminals as controlling terminal; see
n /usr/src/lib/libutil/pty.c and
n /usr/src/lib/libutil/login_tty.c .
The POSIX job control model formalizes the previous conventions used in setting up a process group. Unfortunately, this requires that changes be made in a defined order and with some synchronization that were not necessary in the past. Older job control shells (csh, ksh) will generally not operate correctly with the new system.
Most of the other kernel interfaces have been changed to correspond with the POSIX.1 interface, although that work is not quite complete. See the relevant manual pages, perhaps in conjunction with the IEEE POSIX standard.
Many of the utilities have been changed to work as described in draft 14 of the POSIX.2 Shell and Utilities document. Additional changes are likely in this area. Networking additions and changes
\*(4B provides some support for the ISO OSI protocols CLNP, TP4, and ES-IS. User level libraries and processes implement the application protocols such as FTAM and X.500; these are available in ISODE, the ISO Development Environment by Marshall Rose, which is available via anonymous FTP (but is not included on the distribution tape).
Kernel support for the ISO OSI protocols is enabled with the ISO option in the kernel configuration file. The .Xr iso (4) manual page describes the protocols and addressing; see also .Xr clnp (4), .Xr tp (4) and .Xr cltp (4). The OSI equivalent to ARP is ESIS (End System to Intermediate System Routing Protocol); running this protocol is mandatory, however one can manually add translations for machines that do not participate by use of the .Xr route (8) command. Additional information is provided in the manual page describing .Xr esis (4).
The command .Xr route (8) has a new syntax and a number of new capabilities: it can install routes with a specified destination and mask, and can change route characteristics such as hop count, packet size and window size.
The format of the sockaddr structure (the structure used to describe a generic network address with an address family and family-specific data) has changed from previous releases, as have the address family-specific versions of this structure. The sa_family family field has been split into a length, sa_len , and a family, sa_family . System calls that pass a sockaddr structure into the kernel (e.g. .Fn sendto and .Fn connect ) have a separate parameter that specifies the sockaddr length, and thus it is not necessary to fill in the sa_len field for those system calls. System calls that pass a sockaddr structure back from the kernel (e.g. .Fn recvfrom and .Fn accept ) receive a completely filled-in sockaddr structure, thus the length field is valid. Because this would not work for old binaries, the new library uses a different system call number. Thus, most networking programs compiled under \*(4B are incompatible with older systems.
Although this change is mostly source and binary compatible with old programs, there are three exceptions. Programs with statically initialized sockaddr structures (usually the Internet form, a sockaddr_in ) are not compatible. Generally, such programs should be changed to fill in the structure at run time, as C allows no way to initialize a structure without assuming the order and number of fields. Also, programs with use structures to describe a network packet format that contain embedded sockaddr structures also require modification; a definition of an osockaddr structure is provided for this purpose. Finally, programs that use the .Sm SIOCGIFCONF ioctl to get a complete list of interface addresses need to check the sa_len field when iterating through the array of addresses returned, as not all of the structures returned have the same length (in fact, this is nearly guaranteed by the presence of link-layer address structures). Additions and changes to utilities
New versions of .Xr lex (1) (``flex'') and .Xr yacc (1) (``zoo'') have replaced their AT&T-derived predecessors. These should be installed early on if attempting to cross-compile \*(4B on another system. Note that the new .Xr lex program is not completely backward compatible with historic versions of .Xr lex , although it is believed that all documented features are supported.
A system-call tracing facility is provided in \*(4B that records all of the system calls made by a process or group of processes and their outcomes. See .Xr ktrace (1) and .Xr kdump (1).
A new utility, .Xr sysctl (8), retrieves kernel state and allows processes with appropriate privilege to set kernel state. The state to be retrieved or set is described using a ``Management Information Base'' (``MIB'') style name, described as a dotted set of components.
The kernel runs with four different levels of security. Any superuser process can raise the security level, but only .Fn init can lower it. Security levels are defined as follows:
Normally, the system runs in level 0 mode while single user and in level 1 mode while multiuser. If the level 2 mode is desired while running multiuser, it can be set in the startup script
n /etc/rc using .Xr sysctl (1). If it is desired to run the system in level 0 mode while multiuser, the administrator must build a kernel with the variable .Li securelevel in the kernel source file
n /sys/kern/kern_sysctl.c initialized to -1. Hints on converting from \*(Ps to \*(4B
This section summarizes the most significant changes between \*(Ps and \*(4B particularly those that are likely to cause difficulty in doing the conversion. It does not include changes in the network; see section 5 for information on setting up the network.
The stat st_size field is now 64-bits instead of 32. Doing something like: foo(st.st_size); and then (improperly) defining foo with an "int" or "long" param: foo(size) int size; { ... } will fail miserably (well, it might work on a little endian machine). This problem showed up in emacs as well as several other programs. A related problem is improperly casting (or failing to cast) the second argument to lseek (or [f]truncate) ala: lseek(fd, (long)off, 0); or lseek(fd, 0, 0); The best solution is to include
n <sys/types.h> which has prototypes that catch these types of errors.
Determining the namelen param for a connect call on a unix domain socket should use the SUN_LEN macro. One old way that was used: addrlen = strlen(unaddr.sun_path) + sizeof(unaddr.sun_family); no longer works as there is an additional field "sun_len".
The timezone conversion code uses data files installed in
n /usr/share/zoneinfo to convert from "GMT" to various timezones. The data file for the default timezone for the system should be copied to
n /etc/localtime . Other timezones can be selected by setting the TZ environment variable.
The data files initially installed in
n /usr/share/zoneinfo include corrections for leap seconds since the beginning of 1970. Thus, they assume that the kernel will increment the time at a constant rate during a leap second; that is, time just keeps on ticking. The conversion routines will then name a leap second 23:59:60. For purists, this effectively means that the kernel maintains TAI (International Atomic Time) rather than UTC (Coordinated Universal Time, aka GMT).
For systems that run current NTP (Network Time Protocol) implementations or that wish to conform to the letter of the POSIX.1 law, it is possible to rebuild the timezone data files so that leap seconds are not counted. (NTP causes the time to jump over a leap second, and POSIX effectively requires the clock to be reset by hand when a leap second occurs. In this mode, the kernel effectively runs UTC rather than TAI.)
The data files without leap second information are constructed from the source directory,
n /usr/src/share/zoneinfo . Change the variable REDO in Makefile from "right" to "posix", and then do make obj (if necessary) make make install
You will then need to copy the correct default zone file to
n /etc/localtime , as the old one would still have used leap seconds, and because the Makefile installs a default
n /etc/localtime each time ``make install'' is done.
It is possible to install both sets of timezone data files. This results in subdirectories
n /usr/share/zoneinfo/right and
n /usr/share/zoneinfo/posix . Each contain a complete set of zone files. See
n /usr/src/share/zoneinfo/Makefile for details.
The kernel's limit on the number of open files has been increased from 20 to 64. It is now possible to change this limit almost arbitrarily. The standard I/O library autoconfigures to the kernel limit. Note that file (``_iob'') entries may be allocated by .Xr malloc from .Xr fopen ; this allocation has been known to cause problems with programs that use their own memory allocators. This does not occur until after 20 files have been opened by the standard I/O library.
.Xr Select can be used with more than 32 descriptors by using arrays of ints for the bit fields rather than single ints. Programs that used .Xr getdtablesize as their first argument to .Xr select will no longer work correctly. Usually the program can be modified to correctly specify the number of bits in an int. Alternatively the program can be modified to use an array of ints. There are a set of macros available in
n <sys/types.h> to simplify this. See .Xr select (2).
Old core files will not be intelligible by the current debuggers because of numerous changes to the user structure and because the kernel stack has been enlarged. The .Xr a.out header that was in the user structure is no longer present. Locally-written debuggers that try to check the magic number will need modification.
The system now has a database of file names, constructed once a week from .Xr cron . To find a file by name only, the command locate name will look in the database for files that match the name. This command is much faster than the full filesystem traversal done by find: find / -name name -print
Files may not be deleted from directories having the ``sticky'' (ISVTX) bit set in their modes except by the owner of the file or of the directory, or by the superuser. This is primarily to protect users' files in publicly-writable directories such as
n /tmp and
n /var/tmp . All publicly-writable directories should have their ``sticky'' bits set with ``chmod +t.''
The following two sections contain additional notes concerning changes in \*(4B that affect the installation of local files; be sure to read them as well.