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31
Living Room / Re: Multibooting and Partitioning Experiments
« on: November 11, 2007, 08:32 PM »
Hi saikee,

I don't know how to put this, so it is probably best to apologize beforehand in case I annoy you: Sorry for my bad attitude, no offense intended. :-[ I just try to get things straight in my mind. And also I like to discuss rather than argue.


... a Bios that will read off the first sector of the first hard disk it is asked to boot.  The Bios goes into the 446th to 51oth byte position to read off the 4 primaries.
I think, the BIOS will read the first sector of the hard disk, if it is asked to boot from it. Agreed. It seems to be ?standard? behavior to put it into RAM at location 0000:7C00. But the BIOS does not show any interest in the partition table (447th to 510th byte of the MBR). It is the Initial Program Loader (IPL = the first 446 bytes of the MBR) that copies the entire MBR (512 bytes =446 bytes IPL + 4*16 bytes partition table + 2 bytes signature) to a ?standard? location in memory (from 0000:7C00 to 0000:0600).


If a partition happens to be fat32 which is supported by virtually all OSes then every OS can read/write its content.
Maybe I have a lot of old hardware with old OS, but I think FAT16 is supported by a lot more OS's than FAT32. Not even Windows 95 or Windows NT 4.0 supported FAT32, not to mention MS DOS previous to version 7.1.


fat16 filing system has a maximum address of 4Gb and putting it beyond the first 4Gb area in the hard disk means no OS can access it.
I would like to repeat my statement of reply#6 of this thread:
I have tested my Windows 98 SE again, just to be sure. It is installed on a logical drive. That logical drive is located 12 GB past the start of the drive.
[Select]
First physical sector = 25,430,958   (Cyl 1,583, Hd 1  , Sect 1)
Last  physical sector = 29,623,859   (Cyl 1,843, Hd 254, Sect 63)
It boots OK.
And I want to add that it is a FAT16 formatted partition. It starts 12 GB past the start of the disk and ends 14 GB past the start of the disk. In case of interest, I can try to copy it to the very end of the hard disk (size is 250 GB or 240 GiB) and see if it is bootable. Actually I am interested myself now, so I will check it out and post the result.


I am aware 256 primaries is no object by putting in a hard disk management layer.
Would you mind very much if I took that technical phrase "hard disk management layer" and use it to describe my batch files? It makes it sound as if I knew what I am talking about.


What is good about installing a Linux as a virtual machine inside a Windows host if that Linux cannot communicate with other Linux partition and read/write information?
I have VMware running on Windows XP. In there I can boot Linux from a CDROM (have not yet installed it to a virtual disk) and I get read/write access to my Ubuntu partition which is installed on a logical drive of my physical hard disk. After finishing this post, I reboot into that Ubuntu installation and post what damage I have done. (I have created an empty file: "/WolfWasHere"). Have I misunderstood that question?


I hope that I don't come across as a smartassed Know-it-all, because I feel that I know much too little about multibooting to be able to give advice or even write tutorials like you have done. I appreciate the way you are sharing your knowledge and I am honored that you read this thread and answer my questions. :)



Greetings
Wolf

32
Living Room / Re: Multibooting and Partitioning Experiments
« on: November 10, 2007, 10:41 AM »
I don't own the PC standard but just use it like everybody else.
Yeah, right. Reading your publications I would say: you use it like nobody else.  :up:
But seriously, I am full of admiration for your work. "Der Bootmeister" for president.

Still seriously, if there is such a thing as "the PC standard", where can I read it? I always assumed that the way how CHS values and LBA values are written to the partition table entries are more like a loose convention. I have noticed on many occasions that the partition table (inside the master boot record (MBR)) and more often the extended partition tables (inside the extended partition boot record (EPBR)) written by Ranish Partition Manager (RPM) were declared as errors (partition table error 116, if I remember correctly) by PowerQuest Partition Magic, and PQmagic offered very kindly to correct those errors. Neither with nor without consequent PQmagic correction, have I ever experienced a problem with getting any MS OS to run from logical drive that has an incorrect CHS address in EPBR. Any thoughts on that? My thoughts are these:
  • All tested MS OS don't seem to care about CHS address, but use LBA address instead. Not to care here is meant to say: maybe the OS loader does read CHS address values, but it does not put out a message about them being off the mark.
  • As long as the crucial values are correct, the rest can be ignored or (ab)used otherwise, with no negative consequences. If I regard the boot sequence as a means to the end of having a OS at my command (GUI or CLI), the only negative consequence would be to not have that OS to boss around. Mind you, getting error messages from particular tools that don't like the way other tools or I manage the hard disk is nothing I would call positive consequence, it is merely a nuisance.

If there is a way to get more partitions out in the normal way then I would love to know.
Sorry for this stupid question: is your understanding of "normal way" the same as: only grub build in commands allowed?
Without that limitation I can think of at least one way to get more than 44 logical partitions. I don't want to bore you or the rest of the forum readers (in case there are any left) with lengthy details.
Just for the record: Ranish Partition Manager (shareware) supports a maximum of 32 primary partitions. Trombettworks' system supports as many primary partitions, until I run out of ink or paper (or disk space more likely). I have written for myself a batch that takes over the role of the ink and paper. Currently I juggle with about 50 primary partitions, but I guess the limit is way beyond 256 partitions.

LVM is not universally supported ...
What is LVM, please? Linux Virtual Machine :-* , no, but maybe Linux Volume Manager.
Actually a search came up with What is LVM? Answer: LVM is a Logical Volume Manager for the Linux operating system.


Greetings
Wolf

33
Living Room / Re: Multibooting and Partitioning Experiments
« on: November 09, 2007, 10:39 PM »
Hi saikee!

Thanks for your reply. I have found that my initial problems with a GRUB floppy were probably related to buggy BIOS, bad floppy disk, old hardware or some such. The floppy I have created following your walkthrough in the reply#37 works perfectly :) on only one of my laptops, but not on my desktop or inside a VM on that desktop. :( I have found another way here to create a GRUB floppy on a FAT formatted floppy (uses mkfs -t msdos /dev/fd0). That one, funny enough, is the other way round, works on my desktop and inside VM, but not on my laptop. Anyway, I now think that my first attempts were not all that bad, I might have tested that first floppy on the wrong machine. So thanks again for encouraging me to give it another go.

Have you ever tested GRUB4DOS?
What do you think of the possibilities to load disk images into RAM?
Is there a reward for beating your record of getting 44 different bootable Linux distros (or 44 logical drives) onto a single S-ATA disk? Just kidding. Would I be allowed to use workarounds (non-grub methods) to achieve that?


Greetings
Wolf

34
Living Room / Re: Multibooting and Partitioning Experiments
« on: November 07, 2007, 08:23 AM »
Hi saikee,

thank you for your links! :Thmbsup:

As it will take me a while to read those threads, I wonder if you could answer a basic question:

Is there a limit on the max number of logical partitions on a single HDD (S-ATA)? I mean, if I have an extended partition with 30,000 cylinders, does that allow 30,000 different logical drives inside? Surely not, but you wrote that the limit of 63 logical drives is not true anymore. I could not find yet the answer, still reading ...

Thanks in advance
Wolf


Edit(1): I guess it is 11?

Edit(2): Would you be kind enough to have a look at Reply#16 of this thread and maybe point me in the right direction to create a GRUB boot floppy. At present I use GRUB4DOS on my active primary partition, but I would appreciate any help.

35
Living Room / Re: Multibooting and Partitioning Experiments
« on: October 28, 2007, 06:21 PM »
would that do the same as
4dos /c del /s/y/z \*.*
does for DOS/Windows?

I guess yes. I have found that trying to get my 2nd monitor involved (which is attached to PCI graphics card, 1st monitor is on onboard graphics card) takes so much longer, but messes up things thoroughly as well. :) I am getting better at doing a fresh reinstall.

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