Re: How to install without modifying MBR?
Hi. Good question.
There are a few answers I can give you,
1) The latest Ubuntu installer is remiss by not making you explicitly choose where the Grub boot code is put, except if you choose "something else"/"Advanced". There is a pull-down menu where you can choose among partitions.
2) The Grub boot system does not work reliably when the boot code is put in a partition in the way that the Ubuntu installer and grub-install does it. It creates a dependency between the boot code and the absolute sector address of a file in /boot. There are some circumstances when the location of this file may change.
3) Because of 2) the file, core.img, is put in sectors 1 to 50 (approx) on the disk where it won't move and the boot code is put in the MBR in sector 0, thus wiping out the standard boot code that Windows relies on. This does not mean that the boot code has to be in the MBR. It can be in a partition instead.
4) I agree with you that all the Ubuntu boot stuff should be contained in the Ubuntu partition. But this is not reliably supported by Ubuntu. You can achieve a compromise by installing as normal to the MBR area and then moving just the sector 0 boot code to the start of a primary partition, then restore the standard boot code and set the boot flag for that partition. This will avoid almost all Windows MBR conflict issues.
5) Easier and most reliable is to install Grub to the MBR of a separate disk. Even a USB stick. The Grub MBR and boot file need not be on the same disk as the /boot partition.
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