OSDev.org

Hi,

i know that this is OT and i must apologize for this Question here, but i dont know where to ask else and i think OS Developers have the best Knowledge on this. I dont know whether this is possible or not, but i am looking for a way to start a ISO/IMG File from the HDD. The first Idea was to use some kind of chainloader that can read NTFS Drives, since i run Windows OS with NTFS FS. I dont want to start all my ISO/IMG Images inside a Virtual Machine or burn them on CD/DVD to start from them. This is mainly for Linux Live Systems. I want to be able to select from a kind of list in a bootloader or something like this and start directly into a Image file. I know how the start mechanism works from bios to first bootloader but maybe there is a aproach or someone knows a way to do this. The underlying FS is NTFS and it should work for Windows 2000/XP and Vista, since the Vista Bootloader is a little different from the other NT Lines,...

Thanks in Advance!

Regards

Kerem

I think you can alter the boot.ini using the /kernel switch to do what you want, however, I can not give you exact instructions as to how to do so, because I am actually learning that myself. Post back if you figure it out.

lurner wrote:I think you can alter the boot.ini using the /kernel switch to do what you want, however, I can not give you exact instructions as to how to do so, because I am actually learning that myself. Post back if you figure it out.

Hi, thanks for the reply, but the /KERNEL switch just directs the boot loader to load an alternate kernel file for the operating system, so you cant tell it to start an ISO/IMG file....


Regards

Kerem

keremg wrote:I am looking for a way to start a ISO/IMG File from the HDD.

Well, you obviously could with the methods mentioned above. However, a CD image is meant to occupy a full drive. That means that you have to make the OS believe its actually booting from CD, rather than just some random bits on the harddisk.

Which means you'll have to emulate something. The three real options are:

1. You load a bit of code that intercepts bios calls and makes it appear as if there's another drive, then forward it to a NTFS driver. For starters, this will probably do, but as soon as the kernel enters protected mode, this interface will no longer be called. If you intend to run something like a linux distro, it will at some point fail to find the CD anymore. If its something of your own make, you could probably cope with it.

2. You fully emulate a CD drive containing the image. The result is that you'll effectively end up using a virtual machine. In which case VMware et. al. would probably do.

3. You just copy a bit of the image into memory and then be done with it. You'll need in this case be very careful of wether the system will actually be able to live with it, as any attempts to read from CD will horribly fail. Again, if its something of your own make, it might be possible, but then you might want to consider using GRUB instead.

short answer: if you're trying to start windows/linux from cd this way expect it to fail.

Combuster wrote:

keremg wrote:I am looking for a way to start a ISO/IMG File from the HDD.

Well, you obviously could with the methods mentioned above. However, a CD image is meant to occupy a full drive. That means that you have to make the OS believe its actually booting from CD, rather than just some random bits on the harddisk.

Which means you'll have to emulate something. The three real options are:

1. You load a bit of code that intercepts bios calls and makes it appear as if there's another drive, then forward it to a NTFS driver. For starters, this will probably do, but as soon as the kernel enters protected mode, this interface will no longer be called. If you intend to run something like a linux distro, it will at some point fail to find the CD anymore. If its something of your own make, you could probably cope with it.

2. You fully emulate a CD drive containing the image. The result is that you'll effectively end up using a virtual machine. In which case VMware et. al. would probably do.

3. You just copy a bit of the image into memory and then be done with it. You'll need in this case be very careful of wether the system will actually be able to live with it, as any attempts to read from CD will horribly fail. Again, if its something of your own make, it might be possible, but then you might want to consider using GRUB instead.

short answer: if you're trying to start windows/linux from cd this way expect it to fail.

Hi,

these are all the points i was thinking about, since the Image and the Kernel on the Image expects to read the image from a physical device and if i start to write a layer i will end up in a virtual machine, so i can stay at MSVPC, Bochs, QEMU and other VM's,...

I think i have to stay at my VPC and QEMU Bochses. The Point was to test the images on the fly without wasting optical media on a REAL System and not emulation with a layer in between. Since Llive Images behave different on real hardware, because it is REAL hardware than on VM's. You dont have 3D Suppurt for Video and other Drivers/Hardware like you have the choices on an Real System and can change/replace the Hardware the way you like,...

Regards

Kerem

Waste? Why don't you just buy a few blank CD-RW disks? that way you can update it "on the fly".

Or look into PXE booting... floppy disks?.. etc..

Brynet-Inc wrote:Waste? Why don't you just buy a few blank CD-RW disks? that way you can update it "on the fly".

Or look into PXE booting... floppy disks?.. etc..

You can boot from cd-rw's?

crazygray1 wrote:You can boot from cd-rw's?

Why not? I'm not aware of any technical restrictions associated with CD-RW disks... as long as it has a valid bootloader, it should work just fine..

I didn't know if cd-rw would be supported in many BIOS's if any since cd-r and cd-rw are two different technologies?

Brynet-Inc wrote:

crazygray1 wrote:You can boot from cd-rw's?

Why not? I'm not aware of any technical restrictions associated with CD-RW disks... as long as it has a valid bootloader, it should work just fine..

It works fine. As you said, as long the RW-Media has valid boot sectors its no problem to boot from! But what i wanted was to download a ISO Image, place it on the HDD and make some entry inside a config-alike file and at next reboot i wanted to start that ISO from a Menu entry. But this is not possible so it looks,...possible yes, but not on he fly! I hoped that there culd be a ready 2 use solution for this,...but it does not look like that!

Regards

Kerem

There is a solution, lol. I told you already that you could do this using the boot.ini /kernel switch. I'm not sure what your .IMG consists of, but if it is capable of booting an OS, then it will work.

lurner wrote:There is a solution, lol. I told you already that you could do this using the boot.ini /kernel switch. I'm not sure what your .IMG consists of, but if it is capable of booting an OS, then it will work.

Hi,

could you please give me ann example how i have to format the line with the /kernel parameter, because i really dont know how this should work,...


Regards

Kerem

Not sure mate. Something like:

/kernel=MYBOOT.IMG
/kernel=MYBOOT.EXE
/Kernel=MYBOOT.COM

Something like that should work, but you have to use some Windows program (not bootcfg) to edit the boot.ini, not sure what the name is or how to use it, since I too am still learning how to do this but am too lazy/tired to study it at the moment. Just Google: Boot.ini /kernel switch or maybe someone here knows?

lurner wrote:Not sure mate. Something like:

/kernel=MYBOOT.IMG
/kernel=MYBOOT.EXE
/Kernel=MYBOOT.COM

Something like that should work, but you have to use some Windows program (not bootcfg) to edit the boot.ini, not sure what the name is or how to use it, since I too am still learning how to do this but am too lazy/tired to study it at the moment. Just Google: Boot.ini /kernel switch or maybe someone here knows?

Hi lurner,

be sure that this NEVER works, since the original ntoskrnl and the regarding hal.dll are native PE Images and have the structure and layout of a PE Image, internally compiled as system drivers with entry points and import/export sections, IAT, Resources, and very suprising for me does the ntoskrnl.exe on my retail system have a section called debug with DEBUG Information(symbols to imports/exports) compiled into its optional Header Section that also has some CodeView Block. I mean this is nice, but useless on a retail ntsokrnl.exe...strange! Maybe someone can explain me this,...

And the so called ISO/IMG Files dont have the structure and the NTLDR expects a File like the ones mentioned above! The ISO/IMG have the ISO 9660 / UDF File format which is not executable, its just a layout of a original CD/DVD or relevant Optical Media. No Secrets at all!

Forget about the /KERNEL and /HAL switch!

I think i have to stay at a Emulator like QEMU or MSVPC,....anyway,...if someone doesnt have a good alternative for this,...

Regards

Kerem

Well you did ask how to "make some entry inside a config-alike file and at next reboot i wanted to start that ISO from a Menu entry" and I told you how. Never said it would work for what you're doing. Why not write your own, now its...

cheers