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Booting iso from disk


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#1 cjm51213

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Posted 07 April 2012 - 05:48 PM

Hi Folks,

Years ago I wanted to install Fedora which was distributed as a DVD but I had no DVD burner... So, I developed the technique to copy the iso to my boot partition, copy the selected vmlinuz and initrd.img from the distro isolinux directory, and run vmlinuz with the associated anaconda initrd.img, and Voila! Fedora comes to life. The syslinux stanza looks like this:


LABEL Install

	MENU LABEL ^Install / Upg Fedora-16

	KERNEL /Fedora/16/isolinux/vmlinuz

	INITRD /Fedora/16/isolinux/initrd.img

	APPEND lang=en_US keymap=us


Recently I tried this with other iso images with mixed success. CD iso represent little trouble since they are small enough that MEMDISK seems to have no trouble with them. So the syslinux stanza looks like this:


LABEL UBCD-Pro

	MENU LABEL Ultimate Boot CD (XP-Pro.SP2)

	KERNEL /syslinux/memdisk

	INITRD /iso/UBCD4Win-XP.Pro.SP2/UBCD4Win-XP.Pro.SP2.iso

	APPEND iso raw


And in fact what you see above will "boot" meaning I get the menu provided by UBCD, and I can select items, and I can even get the XP splash screen, but it blue screens, which I assume is UBCD paging in from the wrong device, but I don't really know. For comparison, this image does work perfectly if I burn it to optical media. Does anybody have any insight into what is happening to UBCD after I boot the iso with syslinux from my disk and select the UBCD menu item he provides and he subsequently blue screens?

Thanks for the help,

Chris.

#2 Wonko the Sane

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Posted 07 April 2012 - 06:09 PM

You miss a basic piece of info :ph34r:.
You need a driver to "hook" a NT based mem (or direct) mapped .iso.
What you are trying to boot is NOT the UBCD, it is the UBCD4WIN.

Read this first thing:
http://reboot.pro/8944/

Then search for "WinVblock" and "Firadisk".

In other words, it's not a problem of Syslinux, you need to add a driver to the build or use an emulated floppy drive with it (grub4dos would be probably easier to setup like this).


:cheers:
Wonko

#3 cjm51213

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Posted 07 April 2012 - 07:02 PM

Brilliant, Thanks for the help. Yes, you're right. I am talking about UBCD4Win, and I didn't realize there was a distinction. Sorry for the confusion. I will read that and see if I can understand and follow any instructions.

In the meantime, I thought I'd try an experiment by booting a Fedora Live iso. This suffers from similar behavior, meaning I can boot the iso and ask to run Fedora 16 Live, and watch as it loads, but it fails midway through the load with:
dracut Warning: No root device "live:/dev/disk/by-label/Fedora-16-i686-Live-LXDE.iso" found

I suspect this is failing for the same reason, but one problem at a time...

Thanks for the help,

Chris.

#4 steve6375

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Posted 07 April 2012 - 09:49 PM

see http://sites.google....utorials/fedora
I don't think booting from ISO is supported by Fedora (but I could be wrong!).

#5 Wonko the Sane

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Posted 08 April 2012 - 01:52 PM

see http://sites.google....utorials/fedora
I don't think booting from ISO is supported by Fedora (but I could be wrong!).


Unless something has been done in the last year or so, NO :(, you are right :thumbsup:
http://reboot.pro/13908/

@cjm51213
Though the "symptoms" are similar, the "ilnesses" are DIFFERENT :ph34r:.
Windows NT based systems miss a driver (that you need to add).
Linux builds have - generally speaking - "built-in" .iso support BUT they may miss a mechanism to let the *whatever* (kernel/driver/whatever) actually find the .iso file.

Since Fedora uses Dracut (seemingly - and said from a non-linux guy :blush: probably vastly wrongish opinion - one of the smelliest pieces of sh*t that any programmer ever made, but anyway and UNdoubtedly one of the most poorly mantained/bugfixed one), maybe something in this thread could be of help (or completely fail to - sorry to be this "vague" but not really my field :():
http://www.911cd.net...showtopic=24818

Check this:
http://reboot.pro/5041/page__st__132


:cheers:
Wonko

#6 cjm51213

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Posted 08 April 2012 - 07:18 PM

Hi Folks,

Wow... Where to begin. Steve6375, I'll start with your comment, which is well intended but does not address the original problem. It does have bearing on the justification for the original problem, and I see how you were misdirected. Oh, yeah, and it isn't quite correct, either. Let me explain so I don't bite the hand that is feeding me! I don't want to represent that I am in any way an expert on any of this stuff, but I do know the answer for just this one thing.

First: You absolutely can boot the Fedora-11, Fedora-12 AND Fedora-13 distribution DVD from an iso image on disk. F-11 was the first time I did this. There is a trick! And I had to discover the trick, but it wasn't too hard. You have to extract vmlinux and initrd.img, of course, but you also had to extract the "images" directory and put that where it could be found. The following syslinux stanza is an example, and I'd be happy to give anybody any more detail on this technique, but it is no longer relevant since Fedora-16 works with just vmlinz and initrd.img from the isolinux directory.

LABEL ins

MENU LABEL Ins / Upg Fedora-11

KERNEL /Fedora-11/isolinux/vmlinuz

APPEND initrd=/Fedora-11/isolinux/initrd.img ro lang=en_US keymap=us [u][b]repo=hd:/dev/sda2:/Fedora-11[/b][/u]


The contents of "isolinux" are necessary for booting and one file from images ("install.img" -- kinda gives it away, huh?) is necessary for anaconda to continue with installation. So, you can surmise from that above stanza that I have these paths in my boot partition /Fedora-11/isolinux and /Fedora-11/images, which were extracted from the distribution DVD, and the iso itself is in /Fedora-11 as indicated by the "repo" parameter above...

Second: I am not trying to boot the distribution for this post -- well I am but it is trivial and not the subject of my question; I am trying to boot a Live CD from the iso image on my disk. The small ultra-portables have a CD-ROM as an accessory, so since there are cases where the CD-ROM drive is a luxury, it occurred to me that I might do well to construct a bootable library. Installation/Rescue is fine. Spinrite and various DOS systems work with no problem. UBCD4Win has problems for which I have been given instructions that I am still working to understand. Microsoft installation media in general behave differently, and I haven't gotten to that yet. LiveCD seems to expose a problem with dracut, so I filed a bug with the dracut lads. We'll see where that goes.




With a 500 gig USB disk, I can have ALL my CD/DVD isos in a fraction of the space required by the CD case I had, and backup is a snap. This was originally motivate by the theft of my computer and CD case, which highlighted in a very clear and painful way that optical media may not be easy to replace.

#7 Wonko the Sane

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Posted 08 April 2012 - 07:26 PM

First: You absolutely can boot the Fedora-11, Fedora-12 AND Fedora-13 distribution DVD from an iso image on disk. F-11 was the first time I did this. There is a trick! And I had to discover the trick, but it wasn't too hard. You have to extract vmlinux and initrd.img, of course, but you also had to extract the "images" directory and put that where it could be found. The following syslinux stanza is an example, and I'd be happy to give anybody any more detail on this technique, but it is no longer relevant since Fedora-16 works with just vmlinz and initrd.img from the isolinux directory.

There is a clear misunderstanding here :w00t:.
Booting from .iso means - strangely enough - "booting from .iso" ;): if you extract files from it you are NOT "booting from .iso", you are "booting from .iso AND extracted files", and it is a workaround known since the dawn of time (though of course each distro may need a smaller or bigger set of files extracted).

:cheers:
Wonko

#8 cjm51213

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Posted 08 April 2012 - 07:42 PM

Hi Wonko,

Well, yes... I am not booting from iso by your definition, but I am getting that thing to run with relatively little trouble, unlike my Live CD and my as yet unresearched UBCD4Win woes, which is really the topic of this thread. Those dogs won't hunt... yet.

Chris.

#9 sbaeder

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Posted 09 April 2012 - 04:18 AM

@cmj51213

OK, yes, you are correct in your view of things, but what folks like Steve and Wonko are saying is that for them to help you (or help you understand), we need to try to be as technically correct as possible.

As both have pointed out, in general, the issue is not with the boot loader per se, but with what happens after that...(nad by the way, they are two of the most knowledgeable folks here!)

So in the case of windows, it is the lack of a proper driver to go into "real" mode and no longer use the more simple bios INT13 hooks. Same sort of thign for Linux, in that there isn't a driver that can really read the ISO file (which is why you had to extract some of the files) and not all ISO/Linux are so easy to make this happen.

So, there is no simple answer here that in universal in nature. You really have to dig into the way the bootloader works, and what it chains to (and how that works, and interacts with the previous environment), etc.

Go read and search and study the threads pointed to above, and eventually, you will achieve enlightenment...

:cheers:
Scott

#10 Wonko the Sane

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Posted 09 April 2012 - 07:51 AM

And for the record, try googling for "UBCD4WIN Firadisk" (without quotes).
It is very likely that you will land right here:
http://www.rmprepusb...orials/ubcd4win
which not-so-casually is a tutorial by Steve6375 :worship: which is the exact answer to your declared needs. :smiling9:

You were given a couple good hints ;).

.....
What you are trying to boot is NOT the UBCD, it is the UBCD4WIN.
....

Then search for "WinVblock" and "Firadisk".
.....


But IMHO before replicating the set of instructions you have to understand why they are needed....
(BTW grub.exe is both a DOS app and a Linux kernel, and as such it can be chainloaded by Syslinux/Isolinux allright)

:cheers:
Wonko




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