IMG booting on Qemu but not on VirtualBox

Post by **scottgus1** » 29. Sep 2023, 19:57

It could be. Your VM is booting from Legacy BIOS. Legacy BIOS cannot boot from USB. The "when indicated as the bootable device during the creation wizard procedure of a VM" point is for ISO's only, where the ISO is of a CD image only, nothing else. Since your image was not an official ISO CD image (at least not compliant to the standard) Virtualbox couldn't use it at that input stage.

Post by **fth0** » 30. Sep 2023, 00:15

Since everyone seems to be a little bit confused, I'll sum up what I understood:

The OP had an original ISO image that only contained the ISO 9660 structures. They converted that first image to a raw hard disk image containing an MBR and no ISO 9660 structures. In summary, there were a simple ISO image and a simple raw hard disk image, and no hybrid ISO image was involved at all. The raw hard disk image couldn't be used as an ISO image in VirtualBox, which is expected. If this image would be written to a USB stick, everyone able to boot from USB mass storage devices could boot that USB stick like a HDD or SSD.

How this second image was used in a QEMU command line was not revealed and leaves several possibilities. But I don't see any open question regarding the behavior of VirtualBox.

Post by **mpack** » 30. Sep 2023, 10:56

No, there is no VirtualBox problem here. There is a lack of relevant information coupled with the OPs failure to really understand what an ISO image is. The constant repetition of these facts does not seem to be helping.

davide8226 · Post by **davide8226** » 30. Sep 2023, 17:36

davide8226 wrote: ↑29. Sep 2023, 19:28
mpack wrote: ↑29. Sep 2023, 19:23 I think the moral of this tale is that a hard disk image does not become an ISO simply because you changed the file extension. It remains a hard disk image, only now with a misleading extension.
Ok, so the fact that it initially booted in Qemu and not in VirtualBox (and still does not) is not a source of concern?
I'd guess that the definitive proof would be writing the image on a real USB drive, and see what would happen...?

Anyway, I have solved my problem thanks to the suggestion I got here to convert it to VDI. So, nothing more to expect or complain on my side.

I'll let the discussion about any right or wrong VirtualBox behaviour to you, experts

Thanks again!

Anyway, I have written the raw image on a USB pendrive and tried with an Acer Aspire 1825 PTZ notebook from 2011... and it boots!

I'll let the conclusions to you

P.S.: I have also tried VBoxManage covertfromraw on the official ISO (to be used to be written on a USB, to make the latter bootable) of Arch Linux distro, and the obtained VDI worked as a VM hard disk.
So, given the option I used is convertfromraw, the ISO of Arch Linux distro is a raw image, despite the .iso extension and the fact that the Mac command-line file tool classifies it as an ISO 9660?

. If I dump it with xxd, the ISO has also an EFI boot, which does not seem therefore to be ISO 9660...?
Sorry if OT but I wanted to clear (to me) also this point...

Post by **scottgus1** » 30. Sep 2023, 19:01

davide8226 wrote: ↑30. Sep 2023, 17:36 the official ISO (to be used to be written on a USB, to make the latter bootable) of Arch Linux distro

I've seen ISOs to be used as CD Images to burn to CD or boot from in VMs as a CD, but not an ISO image meant to be written to a USB.

Please post the link to this ISO.

Post by **mpack** » 30. Sep 2023, 19:08

There's no need to post a link. The statement is absurd on its face.

ISO means that the imaged media uses the "ISO 9660" filesystem. No USB flash drive uses the ISO 9660 filesystem. ISO only applies to optical drives and media.

As I said above, the problem here is the OPs failure to grasp what "ISO" means, and possibly even what "filesystem" means, despite being given the correct answer several times.

I admit that I'm now getting rather irritated at the need to repeatedly point out this error, only for the explanation to be ignored and the incorrect claim repeated. We seem to be getting nowhere, and will not change until thought is given to the meaning of the responses.

Post by **scottgus1** » 30. Sep 2023, 19:45

I would like to check if David did find a special "ISO" from Arch Linux that is intended to convert to a USB. If Arch does distribute such a special ISO, then maybe Davide has got something.

Otherwise, if the Arch "ISO" is the standard typical ISO like every other Linux and Windows ISO, then I agree that Davide was really doing some unusual manipulation with the ISO that wasn't needed and which is protected against by Virtualbox but is not protected against by Qemu.

davide8226 · Post by **davide8226** » 30. Sep 2023, 20:23

scottgus1 wrote: ↑30. Sep 2023, 19:45 I would like to check if David did find a special "ISO" from Arch Linux that is intended to convert to a USB. If Arch does distribute such a special ISO, then maybe Davide has got something.

Otherwise, if the Arch "ISO" is the standard typical ISO like every other Linux and Windows ISO, then I agree that Davide was really doing some unusual manipulation with the ISO that wasn't needed and which is protected against by Virtualbox but is not protected against by Qemu.

With the intention of irritating nobody, please find here the link to the ISO I downloaded (which worked as a bootable with my VirtualBox 7.0, but if you dump it seems to contain an EFI MBR and partition, which should not be included in and ISO 9660...? That's why I don't understand how the absolutely right distinction that mpack did between ISO images and raw images may still hold (in principle it should, but...)) :

http://archlinux.mirror.garr.it/archlin ... x86_64.iso

I am sorry again if this is OT or if (most probably) I am not able to fully catch the point.

Post by **fth0** » 30. Sep 2023, 22:15

scottgus1 wrote: ↑30. Sep 2023, 19:01 I've seen ISOs to be used as CD Images to burn to CD or boot from in VMs as a CD, but not an ISO image meant to be written to a USB.

No, you just never looked closely enough.

For more than a decade, many Linux distributions have been distributed now as hybrid ISO images (e.g. Debian/Ubuntu/Arch ISOs). You can burn the ISO image to a CD/DVD and boot the ISO 9660 file system. You can write the ISO image to a HDD/SSD and boot the FAT32/HFS+ file system with MBR/GPT/APM, dependent on your BIOS type. You can write the ISO image to a USB stick, which can present itself as a HDD/SSD/CD/DVD, and boot it accordingly.

You can analyze the Arch ISO image yourself or just look at Re: IMG booting on Qemu but not on VirtualBox, where I already explained it taking a Debian 12.1.0 ISO file that I have lying around.

PS: It looks like nobody is reading (or understanding) my posts.

Post by **fth0** » 30. Sep 2023, 22:45

mpack wrote: ↑30. Sep 2023, 19:08 ISO means that the imaged media uses the "ISO 9660" filesystem.

Yes, but it does not mean that it uses only the ISO 9660 filesystem.

Post by **fth0** » 30. Sep 2023, 23:04

davide8226 wrote: ↑30. Sep 2023, 17:36 Sorry if OT but I wanted to clear (to me) also this point...

No problem from my POV:

The Arch Linux ISO image is a hybrid ISO image, which contains an ISO 9660 file system and a MBR/GPT combined with ISOLINUX. The trick with hybrid ISO images is that anybody can recognize them differently, because they have several personalities simultaneously.

PS: When I wrote in a previous post that "no hybrid ISO image was involved at all", only the two Windows ISO images were in the game (one ISO 9660 only, and one MBR only).

davide8226 · Post by **davide8226** » 30. Sep 2023, 23:52

fth0 wrote: ↑30. Sep 2023, 23:04
davide8226 wrote: ↑30. Sep 2023, 17:36 Sorry if OT but I wanted to clear (to me) also this point...
No problem from my POV:

The Arch Linux ISO image is a hybrid ISO image, which contains an ISO 9660 file system and a MBR/GPT combined with ISOLINUX. The trick with hybrid ISO images is that anybody can recognize them differently, because they have several personalities simultaneously.

PS: When I wrote in a previous post that "no hybrid ISO image was involved at all", only the two Windows ISO images were in the game (one ISO 9660 only, and one MBR only).

Got it (and I was also aware of hybrid images, as I documented myself in order to get how to implement a conversion procedure from Joliet ISO to raw images...).

All is clear, now. Thanks again to you all!

Post by **mpack** » 1. Oct 2023, 11:36

fth0 wrote: ↑30. Sep 2023, 22:45 Yes, but it does not mean that it uses only the ISO 9660 filesystem.

That is precisely what it means, though I do include all later variants of ISO 9660.

AFAIK the Arch Linux project is not involved in defining the ISO standard.

Post by **fth0** » 1. Oct 2023, 16:31

mpack wrote: ↑1. Oct 2023, 11:36 AFAIK the Arch Linux project is not involved in defining the ISO standard.

Agreed. But AFAIK, the ISO 9660 standard is not involved in defining what an "ISO file" is either.

If we want to split hairs, we can say that the "ISO 9660 standard" only defines the "ISO 9660 filesystem" to be used on optical media (including a "System Area", "reserved for system use"). "ISO images" or "ISO files" naturally started as 1:1 copies of "ISO 9660 filesystems" without being explicitly standardized.

Later on, when USB sticks replaced CDROMs as the tool of choice to install operating systems on physical hardware, the SYSLINUX project invented a clever use case for the "System Area", integrating the most common boot systems and therefore making USB sticks (and "ISO files") booting "everywhere".

In consequence, we have a de-jure standard used by Windows ISO files and a de-facto standard used by Linux ISO files. And I don't see where the latter violates the former in any way.

PS: I looked into the ECMA-119 "4th Edition / June 2019" version of the ISO 9660 standard, if that plays a role. I don't intend to buy the original standard.