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Grub 2 in LXF 174

 
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Nuke
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Joined: Wed Feb 09, 2011 12:11 pm
Posts: 211
Location: Chepstow, UK

PostPosted: Tue Jul 16, 2013 11:14 pm    Post subject: Grub 2 in LXF 174 Reply with quote

Must admit I'm a bit lost in Carl Fletcher's Grub 2 article [LXF 174].

He tells us how to install from a Ubuntu/Mint[DEB] distro, then how to install from a Suse/Fedora/[RPM] distro. Fair enough.

But then he says "where you have two .. distros installed, try switching from the one controlling Grub to the other"

Why? Once Grub 2 is installed it can boot either surely, it does not need to be "controlled" by the one you want to boot. Why does he go through a palava of "switching control" from Suse to Mint and then back again? Am I missing something here or is this just for fun ?

I also have a problem with the very concept of Grub being "controlled" by any one distro. I think/thought a boot manager should be OS neutral, especially if it is in the MBR. While, clearly, Grub needs to be installed by one distro or another, after that it should be independent surely?

FWIW, my boot manager is Smart Boot Manager [SBM] in the MBR, and it is this neutral SBM that gives me my choice of OS. To boot a Linux distro it hands over to a Grub [1] in the Boot Sector of that distro's partition which immediately boots it. So I have several Grubs (and a Windows bootloader - and a DOS bootloader believe it or not) around my drives. Come to think of it, those Grubs do have graphical backgrounds appropriate to that distro but I do not mind that because they are exclusively for that distro and in its partition.
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caf4926



Joined: Mon Dec 26, 2005 6:28 am
Posts: 40
Location: The English Lake District

PostPosted: Sat Jul 20, 2013 10:48 am    Post subject: Re: Grub 2 in LXF 174 Reply with quote

Nuke wrote:
Must admit I'm a bit lost in Carl Fletcher's Grub 2 article [LXF 174].

He tells us how to install from a Ubuntu/Mint[DEB] distro, then how to install from a Suse/Fedora/[RPM] distro. Fair enough.

But then he says "where you have two .. distros installed, try switching from the one controlling Grub to the other"

Why? Once Grub 2 is installed it can boot either surely, it does not need to be "controlled" by the one you want to boot. Why does he go through a palava of "switching control" from Suse to Mint and then back again? Am I missing something here or is this just for fun ?

I also have a problem with the very concept of Grub being "controlled" by any one distro. I think/thought a boot manager should be OS neutral, especially if it is in the MBR. While, clearly, Grub needs to be installed by one distro or another, after that it should be independent surely?

FWIW, my boot manager is Smart Boot Manager [SBM] in the MBR, and it is this neutral SBM that gives me my choice of OS. To boot a Linux distro it hands over to a Grub [1] in the Boot Sector of that distro's partition which immediately boots it. So I have several Grubs (and a Windows bootloader - and a DOS bootloader believe it or not) around my drives. Come to think of it, those Grubs do have graphical backgrounds appropriate to that distro but I do not mind that because they are exclusively for that distro and in its partition.

FYI I wrote that

It's just a project.

You are correct that once grub is installed by say Ubuntu it will boot Ubuntu and any other OS's installed (Linux or Windows), that's the idea any way. In practice, it doesn't always work out that way.

You ask why all the switching?
It's just to illustrate the practice. You would be surprised how often we get people asking in the forums..."I just installed Ubuntu to try it.. but I want my XXXX grub back, it's way prettier than Ubuntu's" OR
A user test another distro, planning to use it, but finds it doesn't meet up to expectations, he may want to switch grub back to his other distro etc..

Quote:
I also have a problem with the very concept of Grub being "controlled" by any one distro. I think/thought a boot manager should be OS neutral, especially if it is in the MBR.
Unfortunately it doesn't work that way - at least not at a standard user level. But it is true, technically you can edit any grub menu at boot to do whatever you edit in, assuming the boot option exists and you edit it in correctly, it will boot.

But when a distro is installed and allowed to write grub, as a generalization, it does take control of booting/grub.
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PCNetSpec
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Joined: Sun Feb 21, 2010 3:50 pm
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Location: Cornwall UK

PostPosted: Sat Jul 20, 2013 12:20 pm    Post subject: Reply with quote

Only *part* (stage 1) of GRUB is installed to the master boot record.

the other parts (stages) are in /boot

Think of /boot/grub/grub.cfg .. only the the changes made in "one" distros /etc/default/grub are going to be applied to it .. the one you run "update-grub" from.
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caf4926



Joined: Mon Dec 26, 2005 6:28 am
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Location: The English Lake District

PostPosted: Sat Jul 20, 2013 5:38 pm    Post subject: Reply with quote

PCNetSpec wrote:
Only *part* (stage 1) of GRUB is installed to the master boot record.

the other parts (stages) are in /boot

Think of /boot/grub/grub.cfg .. only the the changes made in "one" distros /etc/default/grub are going to be applied to it .. the one you run "update-grub" from.


Absolutely correct
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