Re: : accessing the MBR in multibooted systems?
On Thu, May 31, 2007 at 09:34:16PM -0400, Daniel Dickman wrote: On 5/31/07, James Hartley [EMAIL PROTECTED] wrote: Section 4.8 of the FAQ discusses how to capture the PBR for multibooting with dd: # dd if=/dev/rwd0a of=openbsd.pbr bs=512 count=1 Two questions. * For stand-alone installations, is the PBR the same thing as the MBR? * More importantly, how can I use dd to access the MBR in a multibooted system of Vista OpenBSD? Thanks for any insight. I can only guess your end goal is to be able to multiboot Vista and OpenBSD. That's the setup I have on my machine. It's a little tricky, but here's basically how I did it: 1) install Vista on a primary partition first. 2) install OpenBSD on another primary partition, make sure to keep the Vista MBR though. (in another words be careful what you're doing during the fdisk stage of OBSD installation). At this point you have both OS's on your machine but can only boot into Vista. So now: 1) Use windows dd from Vista to copy the PBR from OpenBSD onto your windows partition (This app can be found here: http://www.chrysocome.net/downloads/dd-0.5.zip) 2) Note one tricky thing here. When you open the Vista command console to run dd you must right click and select Run as administrator. As an alternative you can during installation create a third MSDOS partition formatted FAT32 to use to transfer the PBR. Create the file using dd during OpenBSD installation. Boot into Vista and fetch the PBR file from the MSDOS partition. Or use an external USB drive for the same purpose. Windowses has a history of being pecky about the MBR and it is generally safest to use Windows bootloader for multibooting. 3) Use the Vista bcdedit command to set OpenBSD as a boot option under Vista. Here's the best tutorial I've seen on the topic (http://www.bsdforums.org/forums/showthread.php?t=48405). Note that if you don't know what you're doing you can very easily lose ALL your data with the smallest of mistakes, so be sure not to try this on a machine that has data you care about unless you have everything you need backup up. Enjoy. -- / Raimo Niskanen, Erlang/OTP, Ericsson AB
accessing the MBR in multibooted systems?
Section 4.8 of the FAQ discusses how to capture the PBR for multibooting with dd: # dd if=/dev/rwd0a of=openbsd.pbr bs=512 count=1 Two questions. * For stand-alone installations, is the PBR the same thing as the MBR? * More importantly, how can I use dd to access the MBR in a multibooted system of Vista OpenBSD? Thanks for any insight.
Re: accessing the MBR in multibooted systems?
James Hartley wrote: Section 4.8 of the FAQ discusses how to capture the PBR for multibooting with dd: # dd if=/dev/rwd0a of=openbsd.pbr bs=512 count=1 Two questions. * For stand-alone installations, is the PBR the same thing as the MBR? no. * More importantly, how can I use dd to access the MBR in a multibooted system of Vista OpenBSD? Read: http://www.openbsd.org/faq/faq14.html#Boot386 over and over until it makes sense to you. Read every single man page linked in that section. Read it about twice more AFTER the answer to the previous question becomes obvious. :) I really hesitate to answer this, but what the heck. Here are the bullet: dd if=/dev/rwd0c of=disk.mbr bs=512 count=1 dd and fdisk are useful guns. That round thing is your disk, those fleshy things on the floor in front of you are your feet. Fire away... Thanks for any insight. Not sure what you are planning on doing with that info, but I'd say goodbye to your data now, it will be harder once it is gone. You are messing with things you had better understand well. OpenBSD will actually be pretty forgiving (assuming you recreate things properly), but I'd bet Vista, given a chance, will try to save you from ever seeing your data again. Knowing how long it takes to reinstall Windows XP and 2003, I can only imagine how long it will take to reinstall (and patch) Vista. Nick.
Re: accessing the MBR in multibooted systems?
On 5/31/07, James Hartley [EMAIL PROTECTED] wrote: Section 4.8 of the FAQ discusses how to capture the PBR for multibooting with dd: # dd if=/dev/rwd0a of=openbsd.pbr bs=512 count=1 Two questions. * For stand-alone installations, is the PBR the same thing as the MBR? * More importantly, how can I use dd to access the MBR in a multibooted system of Vista OpenBSD? Thanks for any insight. I can only guess your end goal is to be able to multiboot Vista and OpenBSD. That's the setup I have on my machine. It's a little tricky, but here's basically how I did it: 1) install Vista on a primary partition first. 2) install OpenBSD on another primary partition, make sure to keep the Vista MBR though. (in another words be careful what you're doing during the fdisk stage of OBSD installation). At this point you have both OS's on your machine but can only boot into Vista. So now: 1) Use windows dd from Vista to copy the PBR from OpenBSD onto your windows partition (This app can be found here: http://www.chrysocome.net/downloads/dd-0.5.zip) 2) Note one tricky thing here. When you open the Vista command console to run dd you must right click and select Run as administrator. 3) Use the Vista bcdedit command to set OpenBSD as a boot option under Vista. Here's the best tutorial I've seen on the topic (http://www.bsdforums.org/forums/showthread.php?t=48405). Note that if you don't know what you're doing you can very easily lose ALL your data with the smallest of mistakes, so be sure not to try this on a machine that has data you care about unless you have everything you need backup up. Enjoy.
