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Re: dual grub install?

From: Jake Thomas
Subject: Re: dual grub install?
Date: Thu, 7 Jun 2012 17:59:15 -0700

With Grub you can chainload the VBR of any partition. Grub (should) goes in the 
MBR + an "overflow" area (either the rest of the first 63 sectors, in the case 
of an MBR-schemed disk, or in a dedicated BIOS_BOOT partition, in the case of 
GPT-schemes disks. That's one reason why I prefer GPT, I can have a dedicated 
partition that is marked specifically for holding the rest of the bootloader 
(and is protected as such by the GPT standard), as opposed to some no-man's 
land that anything can rightfully write over, because that area is not 
protected by the MBR standard to be used only by the bootloader.) so the MBR's 
bootloader can can actually point to any partition's bootloader. However, only 
one can be marked as active. But being marked as active doesn't mean didahly if 
you have Grub because you can tell it to chainload any partition.

And you can always use an external hard drive if you're worried about loosing a 
flash drive. And you can always boot an iso of the recovery disc using QEMU 
with -hda being the real hard drive. In fact, I think you can even install 
Windows with an iso + QEMU if you don't let it reboot in QEMU, but turn the 
whole machine off and boot into the hard drive you're installing Windows to, 
because if I remember right, Windows gets all specific to the hardware _after_ 
making the hard drive bootable. If you went through the whole installation in 
QEMU, Windows would get configured for QEMU's emulated hardware platform, 
rather than the real hardware. That's another advantage of Linux - not getting 
specific to the hardware. You _could_ go through the whole Linux installation 
process in QEMU and it'd boot just fine on your real hardware too.

That's one thing about Windows - booting it. It's not multi-boot compliant. You 
always have to cater to Windows. With Linux I can just say "here's the kernel, 
here's the initial ramdisk, boot it". I don't have to have a bootloader for 
every OS/distro if they're all multi-boot compliant. All you have to do is get 
that kernel and initrd in memory and touch it off. Windows needs a special 
bootloader that doesn't take change (resizing/moving/adding/removing 
partitions) well, often demands to be the first hard drive, and only supports 
booting off a GPT disk if it's EFI booting (last time I checked). Meanwhile 
Linux can do acrobatic stunts such as booting off a software RAID array, 
knowingly booting itself out of an iso, embedded booting...anything you can 
think of - all multiboot compliant.

Sent from my iPhone

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