Re: [edk2] ISO9660 driver

Subject: Re: [edk2] ISO9660 driver

From: Jordan Justen <>


Date: 2012-02-26 23:17:00

On Sun, Feb 26, 2012 at 09:38, Andrew Fish  wrote:
> EFI supports El Torito (CD-ROM standard) which is a subset of ISO-9660. EFI uses El Torito to find a single file on the CD-ROM, and this file contains a FAT partition. This often confused folks as what you see in EFI, and what you see in the OS are totally different.

Yes, the EFI standard support for a CD/DVD is el-torito with an
'emulated' floppy or hard disk image including a FAT filesystem.

But, some EFI systems also include an ISO9660 filesystem driver, so
they can access the disk contents aside from just the el-torito
emulated disk areas.

Additionally, some OS CD/DVD images are created with the /EFI/BOOT
items under the ISO9660 filesystem area.

Perhaps they have noticed it works on certain EFI systems, and
therefore just assume that is the best way to include the EFI support
on the disk.  Or, perhaps they prefer to stick with their current
el-torito 'no emulation' boot image rather than change to an emulated
floppy or hard disk image to support EFI.


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