Why will a iso burned to a CD boot but a iso contents copied to a USB drive will not?

[bigpup]

I am not asking for ways to install to a USB drive and get it to boot.
I know how to do it!

What I am trying to figure out is simply this:

Using any of the recent versions of Puppy Linux, that have the needed boot loader stuff in the ISO, to boot on a legacy or UEFI bios computer.
Example:
Fossapup64 9.5
Slacko64 8.2.1
Etc.....

If you burn the iso contents to a CD.
It will boot with no problem to a working desktop.

If you copy the contents of the ISO to a USB flash drive.
The exact same files are on the USB drive.
The USB drive will not boot.
Yes, The boot flag is set.

Anyone know why?

To boot from a USB drive.
Is there some other needed boot loader stuff that is not in the ISO?
Some special setup needed to use just the files provided by the ISO?

Note:
I am using the USB flash drive setup the way most people will buy it.
One partition, formatted fat32.
Also trying after:
Me setting the boot flag.

[williwaw]

copying the contents of an iso to a USB does not install anything to the MBR in the case of a legacy bios.

setting the esp flag is needed for UEFI

[Feek]

If you copy the contents of the ISO to a USB flash drive.
The exact same files are on the USB drive.
The USB drive will not boot.
Yes, The boot flag is set.

Interesting.
Have you tried Bionicpup32?

I recently read fisunov's post about using the "cp" command to transfer an .iso file to a usb flash drive (vfat).
He says that everything worked except saving changes, which means that booting to a working desktop was ok.

[wizard]

@bigpup

Interesting, when you compare the file contents of the CD to the USB are they identical?

When I was testing different programs for creating bootable CD's and USB's for fossapup64 I found that the programs that create a iso9660(cd) format could always make a UEFI boot. Some could make a hybrid boot CD and only Rufus could make a hybrid fat32 USB.

Thanks
wizard

[mikewalsh]

Hmm. Interesting point, that.

I clearly remember my very first fully-working Puppy install; a USB of the original Tahrpup 6.0 CE in December 2014. I ran this on ye anciente Dell lappie; I copied the ISO contents across to a prepared USB stick - two partitions; a 1 GB swap, and the rest to ext3 - using the old Puppy Universal Installer. I do know for a fact that I made no other modifications to it, because I didn't even know about Grub4DOS at that point in time.

It booted straight up, showing the same splash screen that the ISO showed when booting, along with the delay for adding boot parameters down the bottom. I never did anything there, because again I was as green as grass, and knew nowt of what might be needed, so I just let it run. It booted to desktop, quite uneventfully.

Obviously the ISO booted with isolinux. I'm guessing the USB boot was initiated by syslinux.....at any rate, it booted like that ever afterwards.

---------------------------

This is the very same installer program that I know bigpup is so keen to see removed.....because it doesn't work for newer UEFI machines. It worked great for MBR, however. Perhaps take a look at the script for this, see what might be different to the current crop of installers? (None of which I've ever used, BTW, since my own method is to perform a quick'n'dirty install, followed by manual editing of menu.lst....)

Just my two-penn'orth, FWIW.

Mike.

[Flash]

It seems reasonable to me that UEFI boots from CD in a way that's different from USB. Probably whoever developed the UEFI specifications considered USB to be potentially more dangerous than CD because at the time only Windows could boot from CD, so they didn't make it so hard to boot from CD. That's just my WAG.

[ARAN]

I do think it is related to the "El-Torito" standard for creating bootable optical media.

The hardware of a computer handles the booting from a optical media different form a usb or hard drive media.

Becouse of this El-Torito standard burning a image to a hard drive or a usb drive fails to create a bootable device.

It exist however ISOHybrid images that are crafted to work as 1:1 copies on usb and optical media.

If the ISO image is not a ISOHybrid it will fail to boot on a usb or hard drive if flashed.

So if you burn a ISO image to a usb drive and it fails to boot its becouse it is not crafted as a ISOHybrid Image.

[Phoenix]

Rufus does offer this ability to 'hybrid'.

[williwaw]

@bigpup
can you clarify if you are burning the iso as an image, as the title might imply, or are copying the extracted files from the iso ?

If you copy the contents of the ISO to a USB flash drive.

[bigpup]

Somebody changed the subject.
I am changing it back!

I am simply talking about having the exact same files that are in the iso on the CD/DVD or the USB drive.

I think several posts have stated the added needed requirements for booting from a USB drive.

It is more than just having the same files that are in the ISO.

This topic is not about how to do it, but what added stuff is needed to boot a USB drive and possibly why.

[williwaw]

Popular MBR code programs were created for booting PC DOS and MS-DOS, and similar boot code remains in wide use. These boot sectors expect the FDISK partition table scheme to be in use and scans the list of partitions in the MBR's embedded partition table to find the only one that is marked with the active flag.

https://en.wikipedia.org/wiki/Master_bo ... tstrapping

[ARAN]

Why will a iso burned to a CD boot but a iso contents copied to a USB drive will not?

I see the topic has changed what it was before.

To be able to boot a USB drive a master boot record (MBR) is needed on the USB drive.

The master boot record (MBR) is the 512-byte boot sector that is the first sector of a partitioned data storage device
and can not be copied using a file copy program.

Becouse of this when copying the files from the ISO using a file copy program the master boot record is not copied / written to the usb drive
and it fails afterwards to boot.