Can't dualboot Fedora

Question

I have Windows XP installed on partition C, and then I installed Fedora on ext3 partition.

Now at computer startup I should see two options to select from; either launch XP or Fedora. However, my computer automatically starts Windows XP: I do not have two options at computer startup.

I have a Fedora still installed on ext3, but I can’t boot it. Why?

Answer 1

It looks like Windows has grabbed the boot sector. Linux can boot Windows but Windows can't boot anything else. You need to switch the boot sector back to Linux's. Linux's bootloader (the part of the system that executes first after the code in read-only memory and loads the actual operating system) is called Grub. You can repair Grub from the installation medium (CD, USB, …) that you used to install the system. The steps are described in the manual: Fedora 15 (Grub 1), Fedora 16 (Grub 2). In a nutshell, boot the installation medium in rescue mode (linux rescue), then run the commands

chroot /mnt/sysimage
/sbin/grub-install /dev/sda

Answer 2

As Bernhard suggested, the order of installation can be significant in this type of situation. If Windows was installed after Fedora, the simplest option would be to re-install Fedora.

Why? The most common way to achieve a multi-boot environment such as you've described is to leverage one of the popular Linux boot loaders; Grub or Lilo. The boot loader is a small program that is responsible for loading an operating system kernel into memory then passing execution control to the kernel which will continue to load the operating system.

How does the computer determine what or which boot loader to execute? An on-disk boot sector called the master boot record [MBR]. The MBR is the first sector, 512 bytes, of a disk. On the MBR there is, usually, a set of instructions for loading the appropriate boot loader, called bootstrapping. Fedora likely installed a boot loader for you, probably Grub2, and made the appropriate changes to the MBR.

So what? Windows will overwrite the MBR with its own instruction set, this is why installing Windows first is "recommended" for this type of configuration. Additionally, if you have a two disk configuration with Windows on one disk and Fedora on a separate disk then you will need to ensure that your BIOS is configured to boot from whichever disk MBR includes bootstrapping for your Linux boot loader. In both cases your Linux boot loader must be configured to perform a process called chain loading. This is when a currently executing piece of software is replaced by a different piece of software. In this case, at times, you wish to replace your Linux boot loader with Windows so that you can boot into that operating system instead. Presuming a Grub2 install once again, your configuration could resemble:

menuentry "Microsoft Windows XP" {
insmod chain
set root=(hd1,1)
drivemap -s hd0 hd1
chainloader +1

}

Answer 3

Windows has overwritten the boot sector, as others have said. To install Windows and Fedora follow these steps:

1) Install Windows

• In Windows' partition manager

  1. Delete all partitions.
  2. Create a partition for windows.

• Install windows on the new partition

Notes:

• Leave all space not used by Windows blank and unpartitioned.
• Complete Windows installation including firstboot here.

2) Install Fedora

• In Fedora's partition manager

  • Select "use free space" option

• Install Fedora

Note:

• All other options' default values will work (and are suggested).

3) Update both operating systems and install your apps.

Answer 4

This is probably because you installed Windows after Fedora or somehow the bootloader grub wasn't installed. Dunno if Fedora Live CD has a recovery/reinstall option. If there is it is probably the best way to get around with the problem. Otherwise re-install grub manually (see this).