Reinstalling grub?
in [UK Linux]
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From: Will Kemp on 17 Dec 2008 06:46 jasee wrote: >>> Muppet wrote: >>> >>>> How do I reinstall GRUB please? >>> Buy a copy of my book* and read section 3.8.2. This is the relevant >>> bit: >>> > >> I've often wanted to be able to modify grub and this looks like a good >> explanation, however > >>> (Once you have run grub from the rescue disk). >>> >>>> The way grub describes disk drives and partitions is not >>>> the same as the method used by the running system. Grub needs >>>> to find where the "stage1" program is stored on your disk, and >>>> build this information into the initial loader that it >>>> installs at the beginning of your hard disk. There are three >>>> steps to this process. >>>> 1. Find the stage1 program. If you know where it is you can >>>> skip this step. If not you can use grub to find it. The >>>> program is in a file that will have the path >>>> /boot/grub/stage1 on the running system. >> Running system=an existing installation of Linux? >> >>>> If you have a >>>> separate partition that will be mounted as /boot the file >>>> will be /grub/stage1 within that partition. >> Can't understand this maybe it means if you have a seperate partition >> (from which the machine boots) and it's also mounted as" /boot" then the >> file will >be in that partition in /grub/stage 1? > >>>> If you do not >>>> have a separate boot partition /boot will be a directory >>>> within your root partition and the path to the file will >>>> be /boot/grub/stage1. > >> That makes sense if what I've understood above is correct > >>>> To find the boot loader if you have a separate boot >>>> partition type >>>> find /grub/stage1 >>>> if you have one big partition type >>>> find /boot/grub/stage1 >>>> and if you do not know try both. >>>> When Grub finds the loader it will display something like >>>> (hd0,4) >>>> which means "Partition 4 on hard drive 0". If you have >>>> more than one version of Linux installed choose the one >>>> you want to boot - the partition numbers displayed by >>>> grub may not be the same as the partitions displayed by >>>> fdisk, but they will be in the same order. >>>> 2. Tell grub which program to use. Type this command >>>> root (hdx,y) >>>> replacing x and y with the values that the find command >>>> gave you. >>>> 3. Write the initial loader to disk. Type >>>> setup (hd0) >>>> to write the loader to the first block of the first hard >>>> disk. You can use a different drive name in place of hd0 >>>> to write the loader in another place, but hd0 will be >>>> correct for the vast majority of computers. >>>> You can now leave grub with the quit command and type exit >>>> to reboot your computer. > >> This all looks sensible to me, however it doesn't explain what the stage1 >> program is. It seems as though it's part of grub? So supposing you want to >>> boot multiple versions of Linux, there should be multiple versions of the >> loader in the different partitions? How did they get there? And how do you >> insert mutiple choices in grub? Your quoting is bizarre, but i think the above paragraph is your question... "Stage 1" is the first part of the boot loader - the part that is run by the BIOS on bootup. It's the part that actually sits in the boot sector. This part runs first and then loads "stage 2", which is what actually loads the operating system and passes control to it. The reason there has to be two stages is because the boot sector isn't very big and you can't fit the whole thing into it. So stage 1 is in the boot sector and stage 2 is in /boot/grub (or wherever). There are a couple of ways to boot multiple versions of linux - either you can have a single boot loader in the master boot record (MBR) of the hard drive, which is configured to load the relevant kernel etc, from its partition. Or each version can have its own boot loader in the boot sector of the partition it lives on and there can be a "master" boot loader in the MBR which is configured to "chain" load the boot loaders in the partition boot sectors. -- http://NovemberEchoRomeoDelta.com
From: jasee on 17 Dec 2008 12:30 "Will Kemp" <will(a)xxxx.swaggie.net> wrote in message news:4E52l.6255$We2.5540(a)newsfe24.ams2... > jasee wrote: >>> This all looks sensible to me, however it doesn't explain what the >>> stage1 program is. It seems as though it's part of grub? So supposing >>> you want to >>>> boot multiple versions of Linux, there should be multiple versions of >>>> the >>> loader in the different partitions? How did they get there? And how do >>> you insert mutiple choices in grub? > > Your quoting is bizarre, but i think the above paragraph is your > question... > > "Stage 1" is the first part of the boot loader - the part that is run by > the BIOS on bootup. It's the part that actually sits in the boot sector. > This part runs first and then loads "stage 2", which is what actually > loads the operating system and passes control to it. The reason there has > to be two stages is because the boot sector isn't very big and you can't > fit the whole thing into it. So stage 1 is in the boot sector and stage 2 > is in /boot/grub (or wherever). > > There are a couple of ways to boot multiple versions of linux - either you > can have a single boot loader in the master boot record (MBR) of the hard > drive, which is configured to load the relevant kernel etc, from its > partition. Or each version can have its own boot loader in the boot sector > of the partition it lives on and there can be a "master" boot loader in > the MBR which is configured to "chain" load the boot loaders in the > partition boot sectors. Yes, thanks, that's all pretty clear now (the bizarre quoting was Outllook's Expresses fault, if you save, then edit it, it has already inserted quotes) I'm just not now sure how you get multiple operating system lines in the boot loader, it's pretty clear from the previous explanation how you get one, but can you simply add another using grub?
From: Maurice Batey on 17 Dec 2008 13:17 On Wed, 17 Dec 2008 17:30:12 +0000, jasee wrote: > not now sure how you get multiple operating system lines in the > boot loader I've recently started using the GAG boot loader for that purpose. (Can be installed on a floppy first to try it out, then you can ask it to install itself into the MBR.) For each of the e.g. Linux installations to be booted, you just do a grub-install to its boot partition, before asking GAG to build a boot-list from them. -- /\/\aurice (Retired in Surrey, UK) Linux Mandriva 2.6.27.5-desktop-2mnb 2009.0 32-bit KDE 3.5.10 Virtualbox 2.0.6 (Replace "nomail.afraid" by "bcs" to reply by email)
From: Martin Gregorie on 17 Dec 2008 14:23 On Wed, 17 Dec 2008 17:30:12 +0000, jasee wrote: > > Yes, thanks, that's all pretty clear now (the bizarre quoting was > Outllook's Expresses fault, if you save, then edit it, it has already > inserted quotes) I'm just not now sure how you get multiple operating > system lines in the boot loader, it's pretty clear from the previous > explanation how you get one, but can you simply add another using grub? Just edit GRUB's boot menu, usually /boot/grub/grub.conf -- martin@ | Martin Gregorie gregorie. | Essex, UK org |
From: jasee on 17 Dec 2008 14:37
"Maurice Batey" <maurice(a)nomail.afraid.org> wrote in message news:pan.2008.12.17.18.16.57.406549(a)nomail.afraid.org... > On Wed, 17 Dec 2008 17:30:12 +0000, jasee wrote: > >> not now sure how you get multiple operating system lines in the >> boot loader > > I've recently started using the GAG boot loader for that purpose. > > (Can be installed on a floppy first to try it out, then you can ask > it to install itself into the MBR.) > > For each of the e.g. Linux installations to be booted, you > just do a grub-install to its boot partition, before asking GAG > to build a boot-list from them. Thanks, I've used Gag, it's ok, but it's being picky I know but the icons are enormous! And anyway if you've already got Grub installed it seems unnecessary. |