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Re: Details behind a GRUB2 warning message?

On Sun, Apr 6, 2014 at 1:22 AM, Richard Owlett <rowlett@cloud85.net> wrote:
> Tom H wrote:
>> Let's assume that you have two Linux installations on sda, on sda1 and
>> sda2, and that grub is embedded in the mbr of sda for sda1 and in the
>> pbr/vbr of sda2 for sda2.
> I have two distinct use cases
>   1. one machine has multiple Debian installs {primary and logical
> partitions}
>   2. one machine has WinXP on sda1 with multiple Debian installs on both
>      primary and logical partitions with several logical partitions
> formatted
>      as NTFS
>   1. I have no idea what "pbr/vbr" means
>   2. I've not yet Googled 'chainloading of boot loaders'
>> If it's sda1's grub to which the bios hands over the boot process,
>> you'll be booting the installation on sda2 with one of these three,
>> "linux (hd0,msdos2)/boot/vmlinuz...", "configfile
>> (hd0,msdos2)/boot/grub/grub.cfg", "multiboot
>> (hd0,msdos2)/boot/grub/i386-pc/core.img", and none of them can be
>> affected by the block list issue.
> My machine with only Debian *appears* well behaved.
> My machine with both Windows and Debian gives me fits.

pbr/vbr is partition boot record/volume boot record (I don't know
which of them is more accurate/appropriate) and they refer to the boot
record of a partition as opposed to the boot record of a disk, the

I'm replying to you after 2-3 weeks so you might already have gogoled
chainloading but just in case:

If you're chainloading Linux, then the simplest way is to use one of
the above three methods.

If you're chainloading Windows, then you have to use "set root=(hd0,1)
; chainloader +1"; and you can use "drivemap..." or "parttool..." if
you need to fool the Windows bootloader into thinking that it's on the
first disk or the first partition respectively.

I haven't dual-booted Windows and Linux for a while, but I have, in
the past, when using Windows bootloader rather than grub to boot
WIndows, dd'd the Linux vbr to a file on "c:\" and created a
"c:\boot.ini" entry for Linux. With more recent versions of Windows
you'd have to use bcdedit to add a Linux entry but I've never done so,

FTR, if/when you upgrade your box(es), you should get EFI because it
makes dual-,triple-, ...-booting far simpler.

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