- 1 ReactOS Hardware Requirements
- 2 Choosing an installation strategy
- 3 Getting ReactOS
- 4 Creating the ReactOS Setup CD-ROM
- 5 Installing ReactOS on a real machine
- 6 Installing ReactOS on an emulator
- 7 Installing ReactOS on virtualizing systems
- 8 Limitations
- 9 ReactOS boot options
ReactOS Hardware Requirements
Whether installing ReactOS on real hardware or on an emulator, it is important to know the minimum requirements to install and use ReactOS:
- 32MB RAM (NOTE: ReactOS version 0.2.7 and higher requires a minimum of 64 MB of RAM to install, because of a bug in the first-stage installer)
- IDE harddisk
- FAT16/FAT32 boot partition
- VGA compatible video card
- Standard (PS/2) keyboard
- PS/2 compatible mouse or Microsoft Mouse compatible serial mouse
Furthermore, if you want to try TCP/IP networking, one of the following ethernet cards may work:
- NE2000 clones
- cards based on the Realtek8139 chipset
Other cards might also work, if you provide the appropriate driver.
Choosing an installation strategy
Before installing ReactOS—or indeed, before obtaining ReactOS installation media—it is necessary to decide how ReactOS should be installed on your computer system. Although ReactOS support for IDE disk drives and the FAT16 and FAT32 filesystems is stable as of the 0.2.5 release, ReactOS is still undergoing rapid and fundamental development, with no guarantee that damage will not occur to any hardware or software on which it is run.
Accordingly, the first consideration to make is whether to install ReactOS on a dedicated testing or development machine, or in a contained environment such as running on an emulator without direct disk access. Such options are preferable if the machine on which you will run ReactOS is your primary computer, and/or if you have important data on the computer which you cannot afford to lose (as may well occur if ReactOS experiences a catastrophic error, for example).
If you decide nonetheless to install ReactOS on a disk drive that contains an existing operating system (such as Microsoft Windows XP), you should ensure that the drive is formatted with a filesystem ReactOS can access and write to (which are limited to FAT16 or FAT32, as of the 0.2.6 release), and that there is sufficient free space on the drive such that ReactOS can be installed.
Furthermore, the current hardware limitations to which ReactOS is constrained must be identified and compared to the target computer system (e.g., the limitation that only IDE disk drives may be accessed, and that ReactOS cannot access USB media as of the 0.2.6 release).
Once the available hardware and software situation is determined, the installation media can be selected—for example, if your computer includes an ATA CD-ROM and an IDE hard disk that does not contain irreplaceable data, a good installation option may be to write an ISO image of the ReactOS installation media to a CD-R and proceed to install ReactOS on the IDE hard disk via the CD-ROM.
Currently, ReactOS setup CD-ROMs cannot be bought in stores nor ordered. If you want to install ReactOS on a computer, you will have to create a ReactOS setup CD-ROM by yourself, downloading an image file and writing it to CD-R or CD-RW media with a CD writer. Downloading the image of the ReactOS Setup CD-ROM
Where to download from
Images of the ReactOS setup CD-ROM are physically stored on the ReactOS project page on SourceForge. You can download images directly from the SourceForge site, but some users may prefer the ReactOS.com portal. Both have the exact same downloads though, so there's no real advantage to choosing one over the other.
- Visit ReactOS.com, the ReactOS portal site. This site will always point to the latest release.
- Click on the "Download" link. A page opens with links to packages of the latest release of ReactOS.
- Click on the "ISO Image" link. You will be redirected to one of the SourceForge download servers, and the download will shortly begin.
- Visit the ReactOS Wiki
- Click on the Download ReactOS link. This will always contain the latest offical release
- Select the "ISO image" link
- Visit the ReactOS project page on SourceForge.
- Scroll down to "Latest File Releases"
- Click on the "Download" link for the "reactos" package. A page opens with links to packages of the latest release of ReactOS. The files of the "reactos" package should appear highlighted in a different color.
- Click on the "reactos-version-iso.zip" link, where version is the version number. You will be redirected to one of the SourceForge download servers, and the download will shortly begin.
Creating the ReactOS Setup CD-ROM
- The file you downloaded is a compressed archive in ZIP format, containing a single file named "reactos.iso". This file is the image file of the ReactOS setup CD-ROM in ISO format
- Extract the image file from the archive into a temporary directory
- Write the image file onto CD-R or CD-RW media
Installing ReactOS on a real machine
From a Setup CD-ROM
- Insert the ReactOS setup CD-ROM into a CD-ROM drive and reboot your computer. On the next boot, the ReactOS setup utility will start.
- Follow the instructions on the screen to install ReactOS on your computer.
- After the installation has finished, remove the setup CD-ROM from the CD-ROM drive and press "Return" to reboot your computer. Now, you can start ReactOS by selecting it from the boot menu.
- And that's all
Modifications performed to the Hard Disk to boot ReactOS
FreeLoader, the ReactOS boot loader, is composed by two files: an executable (FREELDR.SYS) and a configuration file in Windows INI format (FREELDR.INI). The two files are copied to the root directory of the active partition
The FreeLoader boot code, that is the small program that loads FREELDR.SYS, can be installed in many ways, depending on the pre-existing operating system. The setup logic tries the following steps in order:
- If the Windows NT/2000/XP boot manager is found on the active partition, the existing boot manager is configured to boot ReactOS. The FreeLoader boot code is written to a file named BOOTSECT.ROS in the root of the active partition, and an entry named "ReactOS" is added to BOOT.INI pointing to BOOTSECT.ROS.
- The Windows NT/2000/XP boot manager is detected by the presence of the files NTLDR and BOOT.INI in the root directory of the active partition
- To uninstall FreeLoader, delete the file BOOTSECT.ROS and remove the "ReactOS" entry from the hidden BOOT.INI file.
- If MS-DOS or Windows 95/98/ME is found on the active partition, the original boot sector is saved to a file named BOOTSECT.DOS in the root directory of the active partition. The FreeLoader boot code is then written to the boot sector of the active partition. FreeLoader thus becomes your primary boot manager, and from its boot menu you will be able to boot both ReactOS and your pre-existing operating system
- MS-DOS and Windows 95/98/ME are detected by the presence of the files MSDOS.SYS and IO.SYS in the root directory of the active partition
- To uninstall FreeLoader, boot from a MS-DOS or Windows Restore floppy disk, and run the command "SYS C:". After this, the BOOTSECT.DOS file can be safely deleted
- If none of the known operating systems is found on the active partition, the original boot sector is saved to the file BOOTSECT.OLD in the root directory of the active partition. The FreeLoader boot code is then written to the boot sector of the active partition. FreeLoader thus becomes the primary boot manager. Note that you will have to edit the FREELDR.INI configuration file by yourself to boot the pre-existing operating system, because FreeLoader has no knowledge of how to do it.
- To uninstall FreeLoader, restore the boot sector of the active partition from the BOOTSECT.OLD file. The details on how to do so are dependent on the operating system you are running
Note: If the active partition uses a FAT32 filesystem, the boot code does not fit into a single sector. Microsoft uses sectors number 0 and 12, while FreeLoader uses sectors number 0 and 14, so there should not be any conflicts with existing boot loaders.
Note: The support for other operating systems will be improved in the future
Installing ReactOS on an emulator
An emulator is a software program that provides a virtual hardware platform. Software instructions that would be run on hardware are now interpreted by the emulator software. This allows you to "run" a different kind of computer hardware and its software in a window on your computer. Although the performance of the software run on a virtual computer will be much slower than on real hardware, it provides several advantages:
You can try out a completely different operating system without tinkering with your real system. You can run potentially unstable software without the fear of damaging your real system. For operating system developers, it provides a way to debug the system without constant reboots.
Bochs (pronounced "box") is an emulator of x86- or x64-architecture computer systems. It can run on the DOS/Windows and Linux operating systems, inter alia, and emulates an IBM PC computer system including a 386, 486 or Pentium CPU. Bochs also provides IO port and BIOS emulation, as well as various other system-level hardware components (such as video display hardware, disk controllers and ethernet cards) such that the emulated system can run diverse operating systems such as Linux, DOS, Windows 95, Windows NT 4, and ReactOS, among others.
The software was initially written by Kevin Lawton and is now maintained by the Bochs SourceForge project.
Installing ReactOS on virtualizing systems
A virtual machine is a software program that is similar to an emulator in that it provides a virtual hardware platform. Software instructions that would be run on hardware are caught by the virtual environment, and depending on the instruction, are either run on the native CPU or emulated in software. Virtual computing allows for much faster operation than standard emulation, as a result of the ability to run a majority of instructions on the native CPU. The performance of the software on a virtual computer will be only slightly slower than on real hardware. Overhead is still an issue for disk I/O and CPU instruction execution, but is generally faster than total emulation.
Advantages of virtual computing:
- You can try out a completely different operating system without tinkering with your real system.
- You can run potentially unstable software without the fear of damaging your real system.
- For operating systems developers, it provides a way to debug the system without constant reboots.
- The performace is much faster then a true emulator such as bochs.
The following virtualizing software systems are known to run Reactos:
VMware is a popular commercial virtual machine software system for the x86 CPU family. It can run on Windows NT, 2K, XP and Linux/FreeBSD. It also provides IO port, BIOS emulation, networking and sound support. VMware can run a number of different "guest" operating systems including *DOS, Windows 9x/NT/2K/XP, ReactOS, Free Unices (*BSD, Linux) as well as many others. VMware is free for 30 days, after that you must purchase a license from their website.
Note: If ReactOS seems to hang during the early stages of boot (before loading the kernel), try to "power off" unneeded hardware, eg: floppy, cdrom, sound etc...
The VMware Player is a free version of the popular VMware for a number of different "guest" operating systems including *DOS, Windows 9x/NT/2K/XP, ReactOS, Free Unices (*BSD, Linux) as well as many others. VMware player is free but does not come with the features VMware Workstation comes bundled with.
Note: If ReactOS seems to hang during the early stages of boot (before loading the kernel), try to "power off" uneeded hardware, eg: floppy, cdrom, sound etc...
QEMU is an open source emulator of the x86 and x64 architectures, that can also function as a partial virtualizer using a kernel module running on Linux. ReactOS is claimed to run on version 0.5.5 of QEMU.
Currently, ReactOS has limited hardware support. A list of the most important limitations follows:
- ReactOS needs at least 32 MBs of RAM to boot, it can be run on 24MB although that's not recommended.
- ReactOS can only be booted from IDE CD-ROMs and hard disks.
Note that booting from CD-ROM is supported only for running the setup program unless you're using the LiveCD option, which is meant to be booted of the CD-ROM continuously. Otherwise booting from CD-ROM for normal use is not recommended. Although it is generally possible, the default configuration will prevent ReactOS from creating a swap file when booted from a CD-ROM. If no swap file is available, ReactOS will stop as soon as it runs out of RAM. In practice, this prevents the use of any non-trivial program
Setup and Boot
Currently, the ReactOS setup utility and boot loader have a number of limitations you should be aware of:
- ReactOS can only be installed on FAT16 or FAT32 partitions.
- The active partition must be a FAT16 or FAT32 partition.
- The setup utility can't check the integrity of filesystems.
- The setup utility will not prevent users from performing dangerous and potentially destructive operations. Be very careful when using it and do not take any warnings lightly.
ReactOS boot options
Kernel command line
The kernel command line is a text string that is passed to ReactOS by the boot loader (usually FreeLoader). It consists of several switches, each of which has a special meaning to ReactOS. A switch is a forward slash (
/) followed by a text string (the name of the switch), and optionally an equal sign (
=) and a text string (the value). If the equal sign is present, then at least one value is required to follow.
The syntax, variables and device strings used by FreeLoader conform to the ARC firmware and boot specification, similarly to the boot system used in all Windows NT implementations (such as the Windows NT bootloader on the x86 architecture, or the ARC console used to boot Windows NT 4.0 on the MIPS, Alpha AXP and PowerPC architectures). Because of this, boot disks and other firmware- or BIOS-accessible devices are specified by each of the bus, disk, slice, and partition values associated with the device.
In FreeLoader the kernel command line is specified in an
Options setting in
freeldr.ini. The following text is an example of the contents of
freeldr.ini, which boots ReactOS from the first partition of the first IDE drive of the computer system:
[ReactOS] BootType=ReactOS SystemPath=multi(0)disk(0)rdisk(0)partition(1)\reactos Options=/DEBUGPORT=SCREEN
As used in the above sample file,
DEBUGPORT is a boot option. By adding the boot option
/DEBUGREPORT=SCREEN, ReactOS will print debugging information to the screen.
The following boot options may be used:
DEBUGPORTas a boot option will enable certain debugging features.
Any one of the following values may set:
SCREEN: Send debug output to the screen.
BOCHS: Send debug output to bochs.
GDB: Enable the GNU debugger (GDB) stub so remote debugging using GDB is possible.
PICE: Enable the Private ICE driver so debugging using Private ICE is possible.
COM1: Send debug output to COM1.
COM2: Send debug output to COM2.
COM3: Send debug output to COM3.
COM4: Send debug output to COM4.
FILE: Send debug output to a file %systemroot%/reactos/debug.log
MDA: Send debug output to MDA (The old text-graphiccard from IBM).
- Specifies baudrate of the serial port to be
[baudrate]bps. Used in conjunction with
- Specifies the IRQ number of the serial port to be
[irq-number]. Used in conjunction with
- Enables profiling. Profiling information will be written in
%windir%\profiler.log. This will slow down the system quite a bit.
- Will restrict ReactOS to use only the first
[maxmem]MB of physical memory.