[conspire] Kubuntu Parted Question

Tony Godshall togo at of.net
Tue Nov 20 15:14:09 PST 2007

Sometimes I think my function in life is not to actually impart any
information (since my memory works well enough to jot rough
relationships but I usually end up having to look up or trial-and-error
the details) but rather to jump in with an "answer" that's just scratchy
enough to get an expert to weigh in and scratch the itch properly. ;-)


On Nov 20, 2007 1:38 PM, Rick Moen <rick at linuxmafia.com> wrote:
> Quoting Tony Godshall (togo at of.net):
> > Boot flag is what DOS bootloaders use to distinguish between data
> > and OS partitions.  It's irrelevant if your bootloader is grub.
> It's irrelevant if your bootloader is GRUB _and_ GRUB's first-stage
> code got written to the MBR.  However, correct me if I'm wrong, but:
> I got the strong impression that most people install GRUB to the
> superblock of the Linux boot partition, not to the MBR.
> If my assumption's correct, then the MBR program area (initial 446 bytes
> out of 512 total in sector zero) probably still contains Microsoft/IBM's
> unnamed MBR bootloader left over from DOS.  That program's just smart
> enough to parse the partition table looking for the first primary
> partition with the "boot" (active) flag, and branch to whatever's in its
> initial sector -- which per my understanding is where people tend to put
> the GRUB first-stage code, which then takes over and controls the rest
> of the boot process, presenting the GRUB boot menu, etc.
> Answering John's questions:
> > Is it all right to have 2 partitions marked with boot flag?
> It's imprudent to have two entries with the active aka boot flag.
> Just don't.  It's possible that your booting software might not be
> confused, but why be in a hurry to find out?  Keep it simple.  Use what
> works.  Don't dick around with boot configurations and partitions
> without knowing what you're doing and why.
> > What does boot flag mean and do?
> It doesn't necessarily "mean" anything:  It's just a flag, i.e., a bit,
> that can either be set or not on each of the four entries in an
> IBM/Microsoft-style partition table in sector zero of a hard drive or
> hard drive-like device.
> See above for how the unnamed IBM/Microsoft MBR bootloader interprets
> the flag if it encounters same.
> It doesn't "do" anything:  It's just a flag, i.e., a bit,
> that can either be set or not on each of the four entries in an
> IBM/Microsoft-style partition table in sector zero of a hard drive or
> hard drive-like device.  A first-stage bootloader in a hard drive or
> hard drive-like device's sector zero either does or does not pay
> attention to the bit, depending on what bootloader it is and how it was
> written.
> > Should I have the lba flag on other primary partitions?
> In the general case, you should leave your partitions the hell alone,
> especially if you're fond of their contents.
> I'm trying to figure out what this line of questioning's all about.
> Several messages ago, you were saying something about problems building
> (i.e., compiling from source) GRUB v. 1.95.  You provided no clue about
> why you were doing such an extremely odd thing as compiling GRUB, or
> in particular why you were compiling it from an upstream source tarball.
> Reading further up to prior threads suggests that, first,
> you were trying to install Kubuntu (version unclear but possibly the
> rather ancient, i.e., mid-2006, Kubuntu Dapper Drake aka v. 6.06) to a
> G3 PPC iMac:  You had problems with a Firewire-attached hard drive, then
> succeeded but weren't running X11.  Then, you stopped talking about the
> PPC box, and suddenly without explanation started talking about some
> other machine -- you didn't really tell us anything about it -- that
> cannot possibly be the PPC, because you talked about installing MEPIS
> (which lacks PPC support) as well as Kubuntu to it.
> On this _second_ box (one infers), you had a series of rather unfocussed
> questions about booting MS-Windows and about booting in general.  You
> seem unclear about where you installed GRUB:  That would probably be
> a big part of your problem.  You talk about MEPIS writing to things, and
> PCLinuxOS writing to things, and Kubuntu writing to things -- but you
> evidently weren't paying attention to where they were writing.
> Maybe you should slow down, stop changing things and thereby continually
> introducing yet more variables, boot a maintenance Live-CD Linux
> distribution, figure out what's _really_ on your two hard drives'
> various partitions, decide what you want bootable and from where,
> construct an appropriate grub.conf, and install GRUB's bootloader.
> > Why are both Partition Tables msdos?
> They are in the standard IBM/Microsoft partition table format used by
> essentially every commonly encountered OS for x86 except for the BSDs.
> This is A Good Thing, in context.
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Best Regards.
Please keep in touch.

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