Is Iso Image Bootable

[Mica Withington]

Iwas trying to create a UEFI-bootable ISO with ImgBurn, but the ISO can not be booted on UEFI based systems. I tried to boot the generated ISO file on a virtual machine (VirtualBox) and two computers (after transferring ISO to USB drive by Rufus). I tried to create an ISO from extracted contents of the Windows 8.1 PE ISO image. Contents of the original image were extracted by automatic mount to a Windows volume. I tried to do the same with other software (mkisofs) and everything worked, so that the original ISO should be OK. I needed to create an ISO as intermediate step in customizing a pre-compiled Win PE ISO image downloaded from this site. I needed to add my own software (IGLib, IGShell and AnnApp based) to the ISO for testing and deployment.

I tried to create an ISO from USB, since this is what I've done when using mkisofs. The USB contents were created by Rufus from the same original ISO image used to generate the other images (Gandalfs_Win8.1U1SE_x64_updateable_final.ISO). I have uploaded the first bytes of generated ISO and the corresponding log file to the Dropbox directory with the above link.

Sorry, I don't know the answer to your question. It would probably depend on what it's meant to be for the file you're pointing it to as the boot image. Normally you'd get the information from a disc that works.

Hi, I've put around first 25 MB of TEST_double_mkisofs_OK.001 to the TEST_double_mkisofs_OK__split subdirectory, split into 19 files of 1.44 MB. I have a slow connection and it willl take some time for all files to be uploaded.

I tried different things and I noticed that the original (Gandalfs_Win8.1U1SE_x64_updateable_final.ISO) is not UEFI bootable on VirtualBox VM, and also if I create new ISO images from the original bymkisofs (same parameters as described) they are only legacy bootable.

As I mentioned, the double bootable ISO image that works was created by mkisofs from the double USB drive that was created from the original ISO image by Rufus, so obviously Rufus added the stuff that makes the USB (and ISO images created from it by mkisofs) UEFI bootable.

OK, that was a missunderstanding. So Gandalfs_Win8.1U1SE_x64_updateable_final.ISO, this was my original and is not UEFI bootable (didn't even check that), and I uploaded only the 1.44 MB part of it if you need to check anything.

To further clarify, the problem is that I can create UEFI bootable ISO from UEFI bootable USB by using mkisofs (creating TEST_double_mkisofs_OK.ISO, which is both legacy and UEFI bootable) but I can not do this by using ImgBurn by suggested settings (the result is TEST_uefi_fromUSB_not_good.ISO, which is not UEFI bootable).

Does it even look like its attempting to load anything from the disc? I don't have anything uefi capable but legacy bios boot sometimes shows error messages when something about the el Torito boot configuration isn't quite right.

I just took an original Windows 8.1 image, mounted it in a virtual drive, pointed build mode at the virtual drive it and configured the 'bootable disc' tab with the UEFI platform, the efisys.bin boot image and set the 'sectors to load' to the value I gave you earlier (2880) and it's booted fine in VMware (set in EFI mode).

I also created a legacy bios bootable version (so just changing the boot image to etfsboot.com, sectors to load to 8 and the platform id to 80x86) and that failed to boot in the EFI enabled VMware. Switch VMware out of EFI mode and the legacy one booted fine.

This is strange because the file is there, and it is precisely the same location and contents as the one contained on the original ISO image and the one contained in the mkisofs - created image that boots without errors on the same configuration (I boot form VirtualBox, have also used my laptob before).

Hmm... This would suggest either that the Windows 8.1 PE disk that I was using is different from the original Windows 8.1 in something that is important for booting, or that VirtualBox' implementation of UEFI is different from VMWare's.

Also, in my previous testing, I could UEFI - boot those DVDs or USBs that I could also boot on VirtualBox on two actual systems (Acer Aspire V3 (quite old) and MS Surface Pro 4), and I couldn't boot those which I couldn't boot on VirtualBox. I haven't yet tried to boot the ISO image created with the latest settings (i.e. 2880 sectors to load) on actual systems (I will not have access for some time).

Is it possible that VMware doesn't have a strict implementation of UEFI standard and is tolerant to some minor error in images created by ImgBurn? It would be nice to verify that on some other systems, but I will not have this possibility for some time.

Based on your last screenshot, I don't believe you issue is related to anything to do with the el Torito / bootable disc stuff at all. After all, it *has* booted, it's just falling over sometime after that.

The strange thing is that when I compare the Gandalfs Win8.1U1SE_x64 updateable final.iso (source image) and TEST_double_mkisofs_OK.ISO (created by mkisofs, bootable in UEFI), practically all files that could be related to booting and to the system, are the same, byte to byte and by paths within ISO. So if the original image really came to the point where Windows are started, how could it fail when the one created by mkisofs does not fail, and all Windows-related files are (in my opinion) exactly the same? As I understand, from the point when Windows begin to load, all data on disk is accessed through the file system paths and not through hardware addresses? This would then mean that if two disks have the same file structure, either Widows should run properly on both or should fail on both?

The USB stick boots perfectly in UEFI mode although it doesn't have boot.catalog. Why is that, is boot.catalog specific to optical drives, or the reason for boot/not boot lies in lower level (not at the file system level)?

I have successfully installed 20.04 and done lots of customization. In the event of a tragedy I would not like to have to start all over again. Is there a simple way (suitable for us newbies) to create a bootable thumb drive image of the customized system, preferably (but not necessarily) including user files, that I could use to restore the system to its current state?I am running on a Dell XPS 410 desktop computer.My apologies if this has been answered previously.Thank you.

Hi,

What version of Etcher are you using and on what platform ? If you trying to flash a downloaded file you could post a link to the file and we can take a look if we can reproduce the problem.

Regards

Thomas

actually thinking about it, ISO images when designed for a CD do not necessarily need to contain a partition table. I am quite sure though that to boot from USB stick you will need one. Converting from one format to the other might not be trivial and you are probably better of downloading an image that is meant for flashing on a USB stick in contrast to being booted from CD.

Etcher copies images to drives byte by byte, without doing any transformation to the final device, which means images that require special treatment to be made bootable, like Windows images, will not work out of the box. In these cases, the general advice is to use software specific to those kind of images, usually available from the image publishers themselves.

-us/software-download/windows10ISO

click on 64-bit,and after downloading flash it with etcher,you will see the notification MISSING PARTITION TABLE

Remember the problem happen with the latest version of etcher both in linux and windows(as I have tested)

I decided I will blog short technical guides when I do something undocumented. These are probably of zero interest to the blog followers and are just meant for Google. If they annoy, tell me and I'll get a wiki or something.

Nice. Now we need a bootloader. Again to the ArchWiki GRUB page (that wiki is a gold mine). We can just follow the Install to external USB stick instructions, mounting the image with kpartx instead of the stick.

This installed GRUB2, easy. Now we have to configure it. This is harder because grub-mkconfig relies on config files present on the running system, while we want to point it at our mounted system. Here the Gentoo wiki page comes handy, and I was about to just create grub.cfg manually when I realized I don't have any kernel installed at all. I'll need to chroot in and install it.

Last step: fix fstab. We don't want to boot successfully just to have the kernel not find its root, so we replace /dev/xvda with /dev/sda1. Finally fix network (in my case assigning the static "Failover" IP that is routed to this machine's MAC via the hypervisor bridge), clean up, and try it!

Use this option and download Media Creation Tool if you want to create bootable USB media to perform a clean install on new or existing hardware. To get started you first need a license to install Windows 11 or have a Windows 10 device that qualifies for an upgrade to Windows 11.

To get started, you will first need to have a license to install Windows 11. You can then download and run the media creation tool. For more information on how to use the tool, see the instructions below.

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