-This program makes it easier to boot NOVA or other operating system
-(OS) in different environments. It reads a so called novaboot script
-and uses it either to boot the OS in an emulator (e.g. in qemu) or to
-generate the configuration for a specific bootloader and optionally to
-copy the necessary binaries and other needed files to proper
-locations, perhaps on a remote server. In case the system is actually
-booted, its serial output is redirected to standard output if that is
-possible.
-
-A typical way of using novaboot is to make the novaboot script
-executable and set its first line to _\#!/usr/bin/env novaboot_. Then,
-booting a particular OS configuration becomes the same as executing a
-local program - the novaboot script.
-
-With `novaboot` you can:
-
-1. Run an OS in Qemu. This is the default action when no other action is
-specified by command line switches. Thus running `novaboot ./script`
-(or `./script` as described above) will run Qemu and make it boot the
-configuration specified in the _script_.
-2. Create a bootloader configuration file (currently supported
-bootloaders are GRUB, GRUB2 and Pulsar) and copy it with all other
-files needed for booting to another, perhaps remote, location.
-
- ./script --server --iprelay=192.168.1.2
-
- This command copies files to a TFTP server specified in the
- configuration file and uses TCP/IP-controlled relay to reset the test
- box and receive its serial output.
-
-3. Run DHCP and TFTP server on developer's machine to PXE-boot NOVA from
-it. E.g.
-
- ./script --dhcp-tftp
-
- When a PXE-bootable machine is connected via Ethernet to developer's
- machine, it will boot the configuration described in _script_.
-
-4. Create bootable ISO images. E.g.
-
- novaboot --iso -- script1 script2
-
- The created ISO image will have GRUB bootloader installed on it and
- the boot menu will allow selecting between _script1_ and _script2_
- configurations.
-
-# PHASES AND OPTIONS
-
-Novaboot performs its work in several phases. Each phase can be
-influenced by several options, certain phases can be skipped. The list
-of phases (in the execution order) and the corresponding options
-follows.
-
-## Configuration reading phase
-
-After starting, novaboot reads configuration files. By default, it
-searches for files named `.novaboot` starting from the directory of
-the novaboot script (or working directory, see bellow) and continuing
-upwards up to the root directory. The configuration files are read in
-order from the root directory downwards with latter files overriding
-settings from the former ones.
-
-In certain cases, the location of the novaboot script cannot be
-determined in this early phase. This happens either when the script is
-read from the standard input or when novaboot is invoked explicitly
-and options precede the script name, as in the example ["4."](#4.) above.
-In this case the current working directory is used as a starting point
-for configuration file search.
-
-- \-c, --config=<filename>
-
- Use the specified configuration file instead of the default one(s).
-
-## Command line processing phase
-
-- \--dump-config
-
- Dump the current configuration to stdout end exits. Useful as an
- initial template for a configuration file.
-
-- \-h, --help
-
- Print short (__\-h__) or long (__\--help__) help.
-
-- \-t, --target=<target>
-
- This option serves as a user configurable shortcut for other novaboot
- options. The effect of this option is the same as the options stored
- in the `%targets` configuration variable under key _target_. See
- also ["CONFIGURATION FILE"](#CONFIGURATION FILE).
-
-## Script preprocessing phase
-
-This phases allows to modify the parsed novaboot script before it is
-used in the later phases.
-
-- \-a, --append=<parameters>
-
- Appends a string to the first "filename" line in the novaboot script.
- This can be used to append parameters to the kernel's or root task's
- command line.
-
-- \-b, --bender
-
- Use `bender` chainloader. Bender scans the PCI bus for PCI serial
- ports and stores the information about them in the BIOS data area for
- use by the kernel.
-
-- \--chainloader=<chainloader>
-
- Chainloader that is loaded before the kernel and other files specified
- in the novaboot script. E.g. 'bin/boot/bender promisc'.
-
-- \--dump
-
- Prints the content of the novaboot script after removing comments and
- evaluating all _\--scriptmod_ expressions. Exit after reading (and
- dumping) the script.
-
-- \--scriptmod=_perl expression_
-
- When novaboot script is read, _perl expression_ is executed for every
- line (in $\_ variable). For example, `novaboot
- --scriptmod=s/sigma0/omega6/g` replaces every occurrence of _sigma0_
- in the script with _omega6_.
-
- When this option is present, it overrides _$script\_modifier_ variable
- from the configuration file, which has the same effect. If this option
- is given multiple times all expressions are evaluated in the command
- line order.
-
-- \--strip-rom
-
- Strip _rom://_ prefix from command lines and generated config files.
- The _rom://_ prefix is used by NUL. For NRE, it has to be stripped.
-
-## File generation phase
-
-In this phase, files needed for booting are generated in a so called
-_build directory_ (see TODO). In most cases configuration for a
-bootloader is generated automatically by novaboot. It is also possible
-to generate other files using _heredoc_ or _"<"_ syntax in novaboot
-scripts. Finally, binaries can be generated in this phases by running
-`scons` or `make`.
-
-- \--build-dir=<directory>
-
- Overrides the default build directory location.
-
- The default build directory location is determined as follows: If the
- configuration file defines the `$builddir` variable, its value is
- used. Otherwise, it is the directory that contains the first processed
- novaboot script.
-
-- \-g, --grub\[=_filename_\]
-
- Generates grub bootloader menu file. If the _filename_ is not
- specified, `menu.lst` is used. The _filename_ is relative to the
- build directory (see __\--build-dir__).
-
-- \--grub-preamble=_prefix_
-
- Specifies the _preable_ that is at the beginning of the generated
- GRUB or GRUB2 config files. This is useful for specifying GRUB's
- timeout.
-
-- \--grub-prefix=_prefix_
-
- Specifies _prefix_ that is put in front of every file name in GRUB's
- `menu.lst`. The default value is the absolute path to the build directory.
-
- If the _prefix_ contains string $NAME, it will be replaced with the
- name of the novaboot script (see also __\--name__).
-
-- \--grub2\[=_filename_\]
-
- Generate GRUB2 menuentry in _filename_. If _filename_ is not
- specified `grub.cfg` is used. The content of the menuentry can be
- customized with __\--grub-preable__, __\--grub2-prolog__ or
- __\--grub\_prefix__ options.
-
- In order to use the the generated menuentry on your development
- machine that uses GRUB2, append the following snippet to
- `/etc/grub.d/40\_custom` file and regenerate your grub configuration,
- i.e. run update-grub on Debian/Ubuntu.
-
- if [ -f /path/to/nul/build/grub.cfg ]; then
- source /path/to/nul/build/grub.cfg
- fi
-
-- \--grub2-prolog=_prolog_
-
- Specifies text _preable_ that is put at the begiging of the entry
- GRUB2 entry.
-
-- \--name=_string_
-
- Use the name _string_ instead of the name of the novaboot script.
- This name is used for things like a title of grub menu or for the
- server directory where the boot files are copied to.
-
-- \--no-file-gen
-
- Do not generate files on the fly (i.e. "<" syntax) except for the
- files generated via "<<WORD" syntax.
-
-- \-p, --pulsar\[=mac\]
-
- Generates pulsar bootloader configuration file named `config-_mac_`
- The _mac_ string is typically a MAC address and defaults to
- _novaboot_.
-
-- \--scons\[=scons command\]
-
- Runs _scons_ to build files that are not generated by novaboot
- itself.
-
-- \--gen-only
-
- Exit novaboot after file generation phase.
-
-## Target connection check
-
-If supported by the target, the connection to it is made and it is
-checked whether the target is not occupied by another novaboot
-user/instance.
-
-## File deployment phase