[gentoo-user] grub over the top of Win XP

[gentoo-user] grub over the top of Win XP

[Mark Knecht]

Hi,
   OK, the target machine is now rebuilt. I decided since I had to
rebuild both WinXP and Gentoo that I'd just put them on the same hard
drive. The Gentoo install is complete right up to the point where I
run grub and write it somewhere and I want to make sure I understand
the right way to do this.

   The disk layout is like this

(MBR) - Win XP
/dev/hda1 - Win XP
/dev/hda2 - extended partition
/dev/hda5 - /boot
/dev/hda6 - swap
/dev/hda7 - /
/dev/hda8 - /home

   Now, my question, where do I write grub? I believe it's into the
MBR and not into partition 1, correct? If so I'd use:

grub

grub> root (hd0,4)
grub> setup (hd0)           (Install GRUB in the MBR)
grub> quit    

   Is this correct?

Thanks,
Mark

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Re: [gentoo-user] grub over the top of Win XP

[Glenn Enright]

On Wed, 07 Sep 2005 04:40, Mark Knecht wrote:
> Hi,
>    OK, the target machine is now rebuilt. I decided since I had to
> rebuild both WinXP and Gentoo that I'd just put them on the same hard
> drive. The Gentoo install is complete right up to the point where I
> run grub and write it somewhere and I want to make sure I understand
> the right way to do this.
>
>    The disk layout is like this
>
> (MBR) - Win XP
> /dev/hda1 - Win XP
> /dev/hda2 - extended partition
> /dev/hda5 - /boot
> /dev/hda6 - swap
> /dev/hda7 - /
> /dev/hda8 - /home
>
>    Now, my question, where do I write grub? I believe it's into the
> MBR and not into partition 1, correct? If so I'd use:
>
> grub
>
> grub> root (hd0,4)
> grub> setup (hd0)           (Install GRUB in the MBR)
> grub> quit
>
Youve got the right idea, but hd0,4 is the logical holder for your linux 
partitions, not the boot partition that holds the grub files. So root is 
your /boot partition, ie hd0,5. 

All this information can be found in your info files for grub, and by using 
your method, section 3.2 (Installing Grub Natively)

-- 

Breaking up Microsoft isn't enough. What the court needs to do is start
breaking kneecaps. 

   -- The BSD Daemon, when asked by Humorix for his reaction
      to the proposed Microsoft two-way split
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Re: [gentoo-user] grub over the top of Win XP

[Christoph Gysin]

Glenn Enright wrote:
> On Wed, 07 Sep 2005 04:40, Mark Knecht wrote:
>>
>>   The disk layout is like this
>>
>>(MBR) - Win XP
>>/dev/hda1 - Win XP
>>/dev/hda2 - extended partition
>>/dev/hda5 - /boot
>>/dev/hda6 - swap
>>/dev/hda7 - /
>>/dev/hda8 - /home
>>
>>grub> root (hd0,4)
>>grub> setup (hd0)           (Install GRUB in the MBR)
>>grub> quit
> 
> Youve got the right idea, but hd0,4 is the logical holder for your linux 
> partitions, not the boot partition that holds the grub files. So root is 
> your /boot partition, ie hd0,5. 

/boot isn't hd0,5, its hd0,1

Christoph
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Re: [gentoo-user] grub over the top of Win XP

[Christoph Gysin]

Mark Knecht wrote:
>    The disk layout is like this
> 
> (MBR) - Win XP
> /dev/hda1 - Win XP
> /dev/hda2 - extended partition
> /dev/hda5 - /boot
> /dev/hda6 - swap
> /dev/hda7 - /
> /dev/hda8 - /home
> 
>    Now, my question, where do I write grub? I believe it's into the
> MBR and not into partition 1, correct? If so I'd use:
> 
> grub
> 
> grub> root (hd0,4)
> grub> setup (hd0)           (Install GRUB in the MBR)
> grub> quit    
> 
>    Is this correct?

Not quite. At least you got the confusing numbering scheme right ;-)

(hd0,4) would be your / partition. But grub expects the partition containing the 
grub installation files, which are located on /boot so it should be (hd0,2)

Christoph
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Re: [gentoo-user] grub over the top of Win XP

[Christoph Gysin]

Christoph Gysin wrote:
> (hd0,4) would be your / partition. But grub expects the partition 
> containing the grub installation files, which are located on /boot so it 
> should be (hd0,2)

stupid me, of course it should be (hd0,1) as mentioned in my other post.

If you're confused now, go with Heinz's "trial and error" way ;-)

Christoph
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Re: [gentoo-user] grub over the top of Win XP

[Heinz Sporn]

Am Dienstag, den 06.09.2005, 21:40 -0700 schrieb Mark Knecht:

> Hi,
>    OK, the target machine is now rebuilt. I decided since I had to
> rebuild both WinXP and Gentoo that I'd just put them on the same hard
> drive. The Gentoo install is complete right up to the point where I
> run grub and write it somewhere and I want to make sure I understand
> the right way to do this.
> 
>    The disk layout is like this
> 
> (MBR) - Win XP
> /dev/hda1 - Win XP
> /dev/hda2 - extended partition
> /dev/hda5 - /boot
> /dev/hda6 - swap
> /dev/hda7 - /
> /dev/hda8 - /home
> 
>    Now, my question, where do I write grub? I believe it's into the
> MBR and not into partition 1, correct? If so I'd use:
> 
> grub
> 
> grub> root (hd0,4)

LOL! Now you gave the poor guy at least three different numbers. One
thing is right though: find /boot within Grub's numbering scheme.
Instead of GUESSING try the following:

1. Enter grub as usual
2. Enter root ( and press tab. Grub lists the available disks /
partitions
3. Select the one you're think is right. At the end of the line e.g.
root (hd0,1) add / and press tab again. Grub now list the directory
content of that root partition. If you found what you were looking for
you're done - else continue with step 2.


> grub> setup (hd0)           (Install GRUB in the MBR)
> grub> quit    
> 
>    Is this correct?
> 
> Thanks,
> Mark
> 
-- 
Mit freundlichen Grüßen

Heinz Sporn

SPORN it-freelancing

Mobile:  ++43 (0)699 / 127 827 07
Email:   heinz.sporn@sporn-it.com
         heinz.sporn@utanet.at
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Re: [gentoo-user] grub over the top of Win XP

[Neil Bothwick]

[-- Attachment #1: Type: text/plain, Size: 1480 bytes --]

On Wed, 07 Sep 2005 09:23:50 +0200, Heinz Sporn wrote:

> >    The disk layout is like this
> > 
> > (MBR) - Win XP
> > /dev/hda1 - Win XP
> > /dev/hda2 - extended partition
> > /dev/hda5 - /boot
> > /dev/hda6 - swap
> > /dev/hda7 - /
> > /dev/hda8 - /home
> > 
> >    Now, my question, where do I write grub? I believe it's into the
> > MBR and not into partition 1, correct? If so I'd use:

Correct, and /dev/hda5 is (hd0,4) despite all the conflicting advice
you've been given.  All my boxes have /boot on hda5 and all use hd0,4
(well, except the iBook which uses that horrible yaboot thing, anyone
who wants to start a grub vs. lilo flame war should be made to use
yaboot).

> LOL! Now you gave the poor guy at least three different numbers. One
> thing is right though: find /boot within Grub's numbering scheme.
> Instead of GUESSING try the following:
> 
> 1. Enter grub as usual
> 2. Enter root ( and press tab. Grub lists the available disks /
> partitions
> 3. Select the one you're think is right. At the end of the line e.g.
> root (hd0,1) add / and press tab again. Grub now list the directory
> content of that root partition. If you found what you were looking for
> you're done - else continue with step 2.

Or, enter grub and type "find /grub/grub.conf" or "find /grub/menu.lst"
and all will be clear.


-- 
Neil Bothwick

TROI : What am I sensing?? I'm sensing INCOMPETENCE, you pretentious
bald pseudo-French dickweed!

[-- Attachment #2: Type: application/pgp-signature, Size: 189 bytes --]

Re: [gentoo-user] grub over the top of Win XP

[Christoph Gysin]

Neil Bothwick wrote:
> Correct, and /dev/hda5 is (hd0,4) despite all the conflicting advice
> you've been given.  All my boxes have /boot on hda5 and all use hd0,4
> (well, except the iBook which uses that horrible yaboot thing, anyone
> who wants to start a grub vs. lilo flame war should be made to use
> yaboot).

Sorry for the confusing answers. I was pretty sure grub doesn't care wether your 
partions are primary or logical, giving each a number starting from 0. 
Appearantly this is *not* the case. From the docs:

      (hd0,1)

    Here, `hd' means it is a hard disk drive. The first integer `0'
indicates the drive number, that is, the first hard disk, while the
second integer, `1', indicates the partition number (or the PC slice
number in the BSD terminology). Once again, please note that the
partition numbers are counted from _zero_, not from one. This
expression means the second partition of the first hard disk drive. In
this case, GRUB uses one partition of the disk, instead of the whole
disk.

      (hd0,4)

    This specifies the first "extended partition" of the first hard disk
drive. Note that the partition numbers for extended partitions are
counted from `4', regardless of the actual number of primary partitions
on your hard disk.

Hope this made things clearer now...

Christoph
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Re: [gentoo-user] grub over the top of Win XP

[Heinz Sporn]

Am Mittwoch, den 07.09.2005, 10:25 +0200 schrieb Christoph Gysin:
> Neil Bothwick wrote:
> > Correct, and /dev/hda5 is (hd0,4) despite all the conflicting advice
> > you've been given.  All my boxes have /boot on hda5 and all use hd0,4
> > (well, except the iBook which uses that horrible yaboot thing, anyone
> > who wants to start a grub vs. lilo flame war should be made to use
> > yaboot).
> 
> Sorry for the confusing answers. I was pretty sure grub doesn't care wether your 
> partions are primary or logical, giving each a number starting from 0. 
> Appearantly this is *not* the case. From the docs:
> 

Grub's a nasty hog, that's for sure (but still superior over Lilo IMHO).
Another very important point to consider is that Grub looks at drive
sequences from a BIOS perspective. Say you have disk 1 (primary IDE) and
disk 2 (secondary IDE). When you boot Grub in sunshine mode it'll see
disk 1 as hd0 and disk 2 as hd1. But if you jump into your BIOS and set
disk 2 to your primary boot medium Grub will change it's perspective and
match disk 2 to hd0.

>       (hd0,1)
> 
>     Here, `hd' means it is a hard disk drive. The first integer `0'
> indicates the drive number, that is, the first hard disk, while the
> second integer, `1', indicates the partition number (or the PC slice
> number in the BSD terminology). Once again, please note that the
> partition numbers are counted from _zero_, not from one. This
> expression means the second partition of the first hard disk drive. In
> this case, GRUB uses one partition of the disk, instead of the whole
> disk.
> 
>       (hd0,4)
> 
>     This specifies the first "extended partition" of the first hard disk
> drive. Note that the partition numbers for extended partitions are
> counted from `4', regardless of the actual number of primary partitions
> on your hard disk.
> 
> Hope this made things clearer now...
> 
> Christoph
> -- 
> echo mailto: NOSPAM !#$.'<*>'|sed 's. ..'|tr "<*> !#:2" org@fr33z3
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Mit freundlichen Grüßen

Heinz Sporn

SPORN it-freelancing

Mobile:  ++43 (0)699 / 127 827 07
Email:   heinz.sporn@sporn-it.com
         heinz.sporn@utanet.at
Website: http://www.sporn-it.com
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         A-4540 Bad Hall
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Re: [gentoo-user] grub over the top of Win XP

[Mark Knecht]

On 9/7/05, Heinz Sporn <heinz.sporn@sporn-it.com> wrote:
> Am Mittwoch, den 07.09.2005, 10:25 +0200 schrieb Christoph Gysin:
> > Neil Bothwick wrote:
> > > Correct, and /dev/hda5 is (hd0,4) despite all the conflicting advice
> > > you've been given.  All my boxes have /boot on hda5 and all use hd0,4
> > > (well, except the iBook which uses that horrible yaboot thing, anyone
> > > who wants to start a grub vs. lilo flame war should be made to use
> > > yaboot).
> >
> > Sorry for the confusing answers. I was pretty sure grub doesn't care wether your
> > partions are primary or logical, giving each a number starting from 0.
> > Appearantly this is *not* the case. From the docs:
> >
> 
> Grub's a nasty hog, that's for sure (but still superior over Lilo IMHO).
> Another very important point to consider is that Grub looks at drive
> sequences from a BIOS perspective. Say you have disk 1 (primary IDE) and
> disk 2 (secondary IDE). When you boot Grub in sunshine mode it'll see
> disk 1 as hd0 and disk 2 as hd1. But if you jump into your BIOS and set
> disk 2 to your primary boot medium Grub will change it's perspective and
> match disk 2 to hd0.
> 
> >       (hd0,1)
> >
> >     Here, `hd' means it is a hard disk drive. The first integer `0'
> > indicates the drive number, that is, the first hard disk, while the
> > second integer, `1', indicates the partition number (or the PC slice
> > number in the BSD terminology). Once again, please note that the
> > partition numbers are counted from _zero_, not from one. This
> > expression means the second partition of the first hard disk drive. In
> > this case, GRUB uses one partition of the disk, instead of the whole
> > disk.
> >
> >       (hd0,4)
> >
> >     This specifies the first "extended partition" of the first hard disk
> > drive. Note that the partition numbers for extended partitions are
> > counted from `4', regardless of the actual number of primary partitions
> > on your hard disk.
> >
> > Hope this made things clearer now...
> >
> > Christoph
> > --
> > echo mailto: NOSPAM !#$.'<*>'|sed 's. ..'|tr "<*> !#:2" org@fr33z3
> --
> Mit freundlichen Grüßen
> 
> Heinz Sporn
> 

Hi Heinz,
   OK, the machine is up and dual booting so everything worked out
fine. Thanks to all for your answers. What I suggested in my first
email was correct. Before I did it I followed Neil's suggestion abut
using the find command within grub. That did clarify things a bit and
made me feel a bit better when I pulled the trigger.

   Anyway, I read all the responses this morning and had a good laugh.
I guess I'm not the only one who has a question or two about how all
of this is done! I must say that I'm appreciative of all the
responses.

   As for the comment above about BIOS order, I think that's correct,
but I tried an experiment on this machine and told it to boot from the
second EDIE controller. That did not change the order grub saw the
drives so I'm not sure every option in BIOS would fit your rule above,
or maybe I still don't understand.

   As for grub rules I think I understand, it's these:

1) The order that the system sees hard drives is the order grub will
enumerate them. For instance, in this system:

/dev/hda - hard drive
/dev/hdb - hard drive
/dev/hdac - cdrom

or this system:

/dev/hda - hard drive
/dev/hdc - cdrom
/dev/hde - hard drive

both produce the same results in grub:

hd0 == /dev/hda
hd1 == /dev/hdb or /dev/hde

where the drives are numbered in the order Linux shows them.

As for partition numbers it is my understanding that grub is always
the /dev/hdX value minus 1.

Beyond that I don't pretend to know anything.

The one thing that always confuses me is the difference between
placing grub in the MBR and placing it in a partition. It is my
understanding that the MBR is a separate part of the drive structure,
and is not part of any partition. Is this true?

When we place an bootloader in the MBR that's what the system jumps to
first? After that the bootloader in the MBR can transfer to either an
operating system or to a second boot loader. I've done this where I
had a copy of grub from Gentoo in the MBR, and then a copy of grub in
a partition. Each copy had their own grub.conf file and managed it's
own set of kernels, etc.

However, what Windows does is a bit beyond me. I suppose it places
it's own bootloader in the MBR. We then overwrite it, but then we have
a command to jump to that OS. (chainloader +1 I suppose?)

Anyway, confusing.

Hey, emerge sync running now. Windows boots, Gentoo boots. All is
good. this is my first dual boot machine that didn't use System
Commander.

Thanks much,
Mark

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Re: [gentoo-user] grub over the top of Win XP

[Willie Wong]

As posted on /. recently, 

On Wed, Sep 07, 2005 at 12:12:21PM -0700, Mark Knecht wrote:
> Beyond that I don't pretend to know anything.
> 
> The one thing that always confuses me is the difference between
> placing grub in the MBR and placing it in a partition. It is my
> understanding that the MBR is a separate part of the drive structure,
> and is not part of any partition. Is this true?
> 
> When we place an bootloader in the MBR that's what the system jumps to
> first? After that the bootloader in the MBR can transfer to either an
> operating system or to a second boot loader. I've done this where I
> had a copy of grub from Gentoo in the MBR, and then a copy of grub in
> a partition. Each copy had their own grub.conf file and managed it's
> own set of kernels, etc.
> 
> However, what Windows does is a bit beyond me. I suppose it places
> it's own bootloader in the MBR. We then overwrite it, but then we have
> a command to jump to that OS. (chainloader +1 I suppose?)
> 

a good source for some basics on how bootloaders work and why we need
them and what the heck MBR actually is:

http://www-128.ibm.com/developerworks/library/l-bootload.html?ca=dgr-lnxw01LILOandGRUB

W
-- 
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the elephant. But since we're physicists, lets consider the alternate example. 
In this case, we scatter the elephant off the fly."
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Sortir en Pantoufles: up 26 days, 23:48
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RE: [gentoo-user] grub over the top of Win XP

[Michael Kintzios]

> -----Original Message-----
> From: Mark Knecht [mailto:markknecht@gmail.com] 
> Sent: 07 September 2005 20:12
> To: gentoo-user@lists.gentoo.org
> Subject: Re: [gentoo-user] grub over the top of Win XP

[snip]
>    As for the comment above about BIOS order, I think that's correct,
> but I tried an experiment on this machine and told it to boot from the
> second EDIE controller. That did not change the order grub saw the
> drives so I'm not sure every option in BIOS would fit your rule above,
> or maybe I still don't understand.

Without knowing the options of your BIOS I can guess two possibilities:

a) your change was temporary and was not saved in the BIOS settings;
b) your grub.map retained the old mapping of devices and that's what was
followed.

> The one thing that always confuses me is the difference between
> placing grub in the MBR and placing it in a partition. It is my
> understanding that the MBR is a separate part of the drive structure,
> and is not part of any partition. Is this true?

Yes.

> When we place an bootloader in the MBR that's what the system jumps to
> first? 

That's what the BIOS jumps to.  The system is still inactive data
scattered on the respective OS partition.

> After that the bootloader in the MBR can transfer to either an
> operating system or to a second boot loader. 

Not exactly: after that, the bootloader jumps to the boot sector of a
partition (also called Partition Boot Record PBR). It is the code in the
boot sector of a partition that will be loading the boot files which
will bring up the OS (bootstrapping).  The PBR also contains the
Parameter Table outlining the layout and file system of the partition.
Note here that the PBR refers to the boot partition (i.e. the partition
that contains the boot files e.g. ntldr et al for WinXP or the Grub
Stage2 files for Linux.)  This can be different to the OS partition
sector.

> However, what Windows does is a bit beyond me. I suppose it places
> it's own bootloader in the MBR.

A *single* booting WinXP will follow the same process as I describe
above (the multiboot M$Windoze arrangement is a bloody mess because it
mixes up the boot files and partition boot sectors of the various
M$Windoze operating systems on the drive).  As you say, WinXP places its
own boot loader in the MBR and it also configures its own PBR.  Both of
which are proprietary M$ code that Grub cannot read (hence the need for
the 'noverify' to avoid Grub hanging).  When we chainload WinXP using
Grub or Lilo we jump to the WinXP PBR and pass on the controls to the
PBR-->ntldr-->WinXP_kernel_image for it to boot.

> We then overwrite it, but then we have
> a command to jump to that OS. (chainloader +1 I suppose?)  

The chainloader +1 points Grub to load the first sector in the partition
we specify.  This is where the PBR exists which thereafter takes over to
load WinXP.

In the non-chainloading boot process (i.e. when Grub boots a system
directly, like Linux) Grub will load the Stage2 boot files, which will
load the kernel image.

I hope this helps.
-- 
Regards,
Mick

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