In the beginning I was fooling around with a quad-boot system including OpenSolaris.
Unfortunately I haven’t been using OpenSolaris that much, so I kept forgetting what the equivalent to the Unix command sudo was. However I still remember that whenever I did use OpenSolaris, somehow it took me a while to find the answer – this might seem strange because when googling for “sudo in opensolaris” at this point in time, you will get the correct answer right away.

Nevertheless I thought this might be worth a tiny blog post and personal reminder that the OpenSolaris equivalent to Unix’s sudo is pfexec: pfexec <command>

or if I may quote Sun/Oracle: "In effect, pfexec functions as a passwordless su or sudo in Linux."

The boot process would then be like this:

• load OpenSolaris GRUB from third primary
1. boot OpenSolaris from third primary
2. load Microsoft bootloader from first primary
3. load Microsoft bootloader from second primary
1. boot Windows 7 from C: (as first primary)
2. boot Windows XP from E: (as second primary)
4. boot Ubuntu (several entries for different kernels) from logical

It turned out that when installing Windows 7 over XP, it kept the second primary partition as booting partition and installed its bootloader there. Choosing load Microsoft bootloader from second primary in GRUB got me to the MS bootloader screen, where I was able to choose which Windows I would like to boot into. However, if I went for load Microsoft bootloader from first primary, I was getting this error message:
BOOTMGR is missing
Press Ctrl+Alt+Del to restart
or in German:
BOOTMGR fehlt
Neustart mit Strg+Alt+Entf

It means that there was no MS bootloader (of any sort) located on the first primary partition (obviously because Win7 kept the second primary as boot partition).
I was able to fix this by booting via the second primary partition into Windows 7 and running “bcdboot.exe C:\Windows C:” on the command line with elevated rights. This command would create the file C:\bootmgr as well as the directory C:\Boot (which contains the BCD registry file along with language files).
After that I was perfectly able to choose the entry from GRUB which would load the MS bootloader from the first primary partition.
(As a note: if you found this blog entry without having the same setup and a working Windows 7 or Vista installation, you can achieve the same effect via the Installation-DVDs. Maybe not via bcdboot but bootrec)

The second effect I encountered was, when I was trying to edit the text of the MS bootloader on the second partition (change “Earlier Windows version” into “Windows XP”), which is done via bcdedit.exe, all I found was this error message:
The boot configuration data store could not be opened.
The system cannot find the file specified.
in German:
Der Speicher für die Startkonfigurationsdaten konnte nicht geöffnet werden.
Das System kann die angegebene Datei nicht finden.
The reason for this is, bcdedit looks for its registry file (\Boot\BCD) only on the active partition. (You can check this on this Microsoft site)
Note: BE CAREFUL about the program with which you make a partition active! You can safely do this for example via GRUB or Gparted. I strongly discourage from using diskmgmt.msc (under Windows): it removed Ubuntu’s swap and root partition from the partition table and I had no choice but to reinstall Ubuntu (this might be a bug in the Win 7 RC, but I think it’s rather a bug in the disk management console itself).

So, after some fuss about changing the active partitions back and forth while setting messages for the (different) MS boot loader(s), I renamed (just in case) the folder \Boot and file bootmgr on the second(!) primary partition, leaving just NTLDR on it.
Because Windows XP was booting just fine, I am assuming, that an MS bootsector first looks for bootmgr and if it doesn’t find one, it looks for ntldr. (The reason why I believe this is, if I renamed the file ntldr as well, I got the above message about BOOTMGR missing).

The current setup now looks like this (after making the third primary, OpenSolaris, partition active again):

• load OpenSolaris GRUB from thirrd primary
1. boot OpenSolaris from third primary
2. load Microsoft bootloader from first primary, which boots via bootmgr (into Win7)
3. load Microsoft bootloader from second primary, which boots via ntldr (into WinXP)
4. boot Ubuntu (several entries for different kernels) from logical

The primary targets were Windows XP (SP3) and Ubuntu (9.04) for coding purposes, secondly Windows 7 RC for testing purposes and OpenSolaris for experience.
I did a lot of installing and reinstalling this past week, until I finally managed to get all four systems working and accessible.

The original partitioning plan was to have two primary partitions and a few logical partitions (inside an extended partition, of course), so there will be room for more systems. After installing Windows XP to the second (primary) partition and Windows 7 in the first, I found out, that the OpenSolaris installer did not create a logical partition (as expected) in the extended partition, but deleted the extended and created a solaris partition (with new size) instead. But because I wanted OpenSolaris to be in a logical partition, I used GParted to created the extended partition again and prepared a dedicated (logical) partition for OpenSolaris. Unfortunately OpenSolaris doesn’t see behind the walls of the extended partition, so – again with GParted – I shrunk the extended and created a third primary partition for OpenSolaris. This time the installer used the partition correctly – nevertheless it contains bugs, and that’s why the installation failed on first try. But with the help of this awesome guide I managed to also take this hurdle. Finally, after installing Ubuntu, I decided I would want to use OpenSolaris’ grub rather than Ubuntu’s (I can’t quite recall whether it was just a visual reason or whether there was more…).

Furthermore I had to face other issues: Windows XP installed itself on drive E:, because it recognized the first primary partition as C: and the card reader as D: (even though E: is the second primary partition), I still haven’t figured out why. Also, after installing Windows 7 and OpenSolaris, I couldn’t boot XP anymore (copying NTLDR and stuff didn’t help). And last but not least, for (still) unknown reason, Windows 7 wouldn’t start bcdedit anymore (yes, even though I started it from a commando prompt with elevated rights).

In order to get Windows XP booting again, I had no choice but to reinstall it (fixmbr from the installation disk wouldn’t work). So I also had to reinstall Windows 7, because from the RC disk I couldn’t start bcdedit, either. This time, however, the Windows 7 installer did not recognize Windows XP as a previously installed version – nevertheless I was able to add Windows XP to the MS bootloader.
OpenSolaris and Ubuntu were still were they belonged, but I had to get them booting again. Trying to restore OpenSolaris’ GRUB (and load it into the MBR) failed with read/write errors, as also shown in this thread. I tried it many times, never successfully though. I thought, the heck with it, I’ll use Ubuntu’s GRUB. Well, I wasn’t able to restore that one, either: stage1 couldn’t be read correctly. According to this wiki entry, with an inode size other than 128, GRUB isn’t able to read from the filesystem. I thought the situation is rather kinda stupid, that the Ubuntu installer creates a partition with an inode size that GRUB won’t be able to read? So I decided to try with OpenSolaris’ GRUB again.

I could boot into OpenSolaris, but just using the LiveCD and entering GRUB commands manually (rootnoverify (hd0,2), chainloader +1) – because at the moment, Windows 7′s bootloader was booting at system start. Since trying to restore OpenSolars’ GRUB back to the MBR (see this) still failed, I was again looking for solutions online. I stumbled across this page (currently only accessible via Google cache), which sounded really easy: just activate the OpenSolaris partition again. Could it really be that simple? It was. After making the partition active, GRUB fired up at system start, and I could boot into all four systems. For Ubuntu I had to adjust the menu.lst settings though: Jaunty uses uuid rather than root by default, but somehow OpenSolaris’ GRUB can’t yet deal with this.

Status quo: At system start I will see the OpenSolaris GRUB with Windows 7, Windows XP, OpenSolaris and Ubuntu as boot options. Windows 7 gets me to the Microsoft bootloader (where I again can choose between 7 and XP, which I added via bcdedit in the beginning). Otherwise I can boot the three remaining systems directly.

Finally, I got the system I wanted: Four operating systems, bootable without inconvenience

[UPDATE 07/07/09:] In order to fix problems with the Windows boot loader, I was using the description at this page.
But using the “manpages” via bcdedit.exe /? also helped. [/UPDATE]