Re: Problems with dual boot and grub

Jeff Vian wrote:

Jim Cornette wrote:

jludwig wrote:

How does toe BIOS know to go to that partition???

The bios will get information from the partition table. For example, you can set the active partition on hda1,hda2 or hda3 on my setup. They are primary partitions. The active partition is marked with an * for the active partition using fdisk (linux version).

You can't boot from hda4 (extended container) or from hda5 (partition in an extended partition, BIOS is not smart enough to do this.) So you should be able to boot from any partition that you install grub in, as long as it is a primary partition.

Why I have an extended partition that is all used up by linux swap is a bit worthless, but that is the way the installer set it up.

You cannot have more than 4 partitions on a drive. When the 4th partition is created it makes it an extended and then creates the logical partition inside, thus hda5

You can set the active partition using the fdisk for windows also. I believe it uses "A" to denote which is the active partition.

Jim

  Device Boot    Start       End    Blocks   Id  System
/dev/hda1   *         1      2173  17454591    7  HPFS/NTFS
/dev/hda2          2174      2186    104422+  83  Linux
/dev/hda3          2187      3583  11221402+  83  Linux
/dev/hda4          3584      3648    522112+   f  Win95 Ext'd (LBA)
/dev/hda5          3584      3648    522081   82  Linux swap

AFAIK you can only have one "active" partition on a drive, thus only one to boot from.

The BIOS goes to the mbr first and if it is not redirected by the mbr content, it goes to the only active partition that you mentioned.

On this setup, grub is installed in the mbr. If the mbr was overwritten, it would boot into the partition marked active (XP in example)

If I installed grub to /dev/hda2 and then made the partition active, grub will boot and be able to redirect the boot according to the grub.conf file. I could boot into grub without it being installed in the mbr.

If you have an installation that is located in an extended partition, you couldn't boot into it without grub being installed in the mbr. This is from my experience. On another system that I have, I use the mbr to boot an installation that is installed on the extended partition(http/ftp installed fedora core development). I then chainload two other installations that I have grub installed in hda1 (boot for Fedora Core1) and hdb2 (boot for fedora core 2 test) respectively. I haven't found a self supporting way to boot grub on an extended partition any other way than on mbr though. Sorry for repeating.

So you are right about only one active partition.

Jim