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OpenBSD Installation and Upgrading Installing and upgrading OpenBSD. |
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MultiBooting OpenBSD.
I try to make a multibooting system between openbsd and WinXP but i have some problems. Situation as below...
1: I have total size of 60GB hard disk. 2: Drive C: 26.5GB and i deleted drive D: for openbsd installation of size 29.9GB. 3: This is what the system shows Disk: wd0 Offset: 0 Signature: 0xAA55 Starting Ending LBA Info: #: id C H S - C H S [ start: size ] ------------------------------------------------------------------------ *0: 07 0 1 1 - 3470 254 63 [ 63: 55761552 ] HPFS/QNX/AUX 1: 00 3471 0 1 - 7294 254 63 [ 55761615: 61432560 ] Extended LBA 2: 00 0 0 0 - 0 0 0 [ 0: 0 ] unused 3: 00 0 0 0 - 0 0 0 [ 0: 0 ] unused offset:55761615 Signature:0xAA55 Until this step, i'm not sure how to continue with. How do i install openbsd in the freespace 29.9GB? I don't understand how Starting and Ending C H S works. please help. |
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Be sure to study Section 4.8 of the FAQ which describes the steps needed to create a multibooted environment with Windows using Windows' boot manager: http://openbsd.org/faq/faq4.html#Multibooting |
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That is approximately 117 million sectors. (You did not show the complete fdisk output, which includes the number of sectors and the disk geometry.) Your two MBR partitions on the drive extend through LBA 61432560, so only about 30GB of your 60GB is allocated in MBR partitions.
Disk geometry (cylinder / head / sector ) is no longer as critical as it once was long ago, as all modern drives have on-board electronics that manage their own physical geometry, which vary greatly. Most EIDE/ATA/SATA drives inform their controllers they have a cylinder geometry containing 255 read/write heads and 63 sectors per track, which has nothing to do with their internal physical geometries. Even so, many BIOSes and OSes rely on MBR partitions starting on cylinder boundaries. However, note that Partition #0 does not start at the beginning of cylinder #0, but starts at the beginning of the second track. The first track (63 sectors) is reserved for the MBR and related structures. If the disk has a BSD disklabel, it can be found in here as well. OpenBSD's fdisk(8) gives you complete control of MBR partitioning. You must set your OpenBSD MBR partition to start on a cylinder boundary. Primary partition #0 is your Windows NTFS C: drive Primary partition #1 is an area reserved for extended partitions. I can only guess that your "deleted" D: drive may have been configured as an extended partition. If so, be aware that deleting the extended partition does not delete this reserved area. If you have no extended partitions any longer, or do not need any, you may delete this extended partition (editing any partition and setting its ID to 0 will mark the partition unused. You may also reuse the partition and/or resize it. OpenBSD MBR partitions use Partition ID A6. You may keep Partition #1 as is, or reuse it, or mark it unused and select another primary partition for OpenBSD. In all cases, you will want to edit in CHS mode. (See the -e option in the fdisk(8) man page.) Partition #0 uses cylinders 0-3470, and Partition #1 uses cylinders 3471-7294. If you are replacing Partition #1 with an OpenBSD partition, edit the partition, set the partition ID to A6, request editing in CHS mode, and leave its starting cylinder as 3471. Set its ending cylinder wherever you want. The partition editor will show you the ending cylinder number, and, if you select it, will show you the final head/sector numbers, which may be shorter than 255/63. If you are keeping Partition #1, edit Partition 2 or 3, and set its starting cylinder to 7295. |
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For numerous reasons, hard drives in the mid-'80's to early '90's were logically partitioned into smaller logical block devices. Partitions were used to keep the size of logical devices to within MS-DOS' restrictions, & allow other operating systems to be installed on the same block device. MS-DOS restricted the number of primary partitions to four, & this legacy persists today. Extended partitions was a hack added later to allow more logical devices to be configured. Even if it was a hack, it was a clever hack. Extended partitions were implemented by having the MBR partition entry point to yet another table specifying the logical partitions within that particular extended partition. When a Wintel computer first boots, it will go through POST & initialize all devices found in the system. Once stasis of the overall system has been reached (including spinning up the hard drive(s)...), the BIOS will search for its configured primary boot block device, & the last thing done before relinquishing control is determine whether the MBR signature, 0xAA55 (also called boot sector's magic number...) has been written to 0x01FE & 0x01FF in the first sector of the boot device. If this value is found, it then loads the boot sector into memory, & begins to execute instructions. The first instructions found in the MBR checks the validity of the four partitions. Only one partition can be marked active, & execution is intended to abort if this criteria is not met. This is the role OpenBSD's fdisk(8) (or any other operating system's fdisk(8)-like utility...) plays in the installation process. It will initialize the boot sector with the appropriate instructions, & provide an editor for manipulating the MBR's partition table. If a partition is to be marked active, fdisk(8) will ensure that only one is marked active. More exciting information can be found in Section 14.6 of the FAQ: http://openbsd.org/faq/faq14.html#Boot386 Class dismissed. |
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jggimi, thanks for your explanation. I'm still a newbie and for my current knowledge that's way too complicated for me... I would like to install openbsd on the partition #1(deleted drive D); how should start?
It will be great if u help me. |
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The OpenBSD install script runs the fdisk(8) program for you. If you answer the question, "Do you want to use *all* of <drive> for OpenBSD?" with the default "no", the install script places you in an interactive fdisk console session (# fdisk -e <drive>). If you answer the question with "yes", it will issue an fdisk reinit, rewriting the MBR table, creating a single A6 MBR partition the spans the entire drive.
After the fdisk program (interactive or the entire drive), the install script then places you in an interactive disklabel(8) session to create the BSD partitions. |
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Step by step, to use the existing MBR Partition #1 for OpenBSD, without changing its size (Untested, but may be helpful as a general guide):
Last edited by jggimi; 22nd October 2008 at 11:54 AM. |
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The Jggimi howto is fantastic. I agree with Jggimi about boot loader. I also prefer GAG over Windows boot loader. I have only one multiboot machine. The story of that machine goes something like this. I got a laptop from my University as my official personal computer. The laptop was pre-installed with Windows XP professional.
I took GParted and moved the Windows XP about 7 GB forward towards extended partition. I installed the GAG and added Windows XP to its menu. Then I did installation along Jggimi description on the first 7GB of the hard drive. I added the OpenBSD to GAG menu and I have now dual boot laptop. It is interesting to see that my default OpenBSD desktop installation including all of multimedia, TeXLive and a full web-browser is less than 2GB. On the another hand my minimal Windows XP installation is 19GB. |
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Does anyone happen to know if the OpenBSD root partition must still be installed within the first 8GB of the disk? Or is that a thing of the past?
Been a while since I've done an OpenBSD/Windows multiboot installation. |
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http://www.dewassoc.com/kbase/hard_d...e_barriers.htm |
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