[CentOS] mkisofs help?

James Pearson james-p at moving-picture.com
Wed Mar 24 20:26:31 UTC 2010

Slack-Moehrle wrote:
> Hi All,
> I am following: http://www.linuxinsight.com/how-to-flash-motherboard-bios-from-linux-no-dos-windows-no-floppy-drive.html
> to make a bootable CD to flash my bios
> I get to mkisofs step, but what I get is not what I think I want.
> I dont understand if I unmount /tmp/floppy how the Mkisofs command of: mkisofs -o bootcd.iso -b FDOEM.144 FDOEM.144 how I get everything in /tmp/floppy
> Here is what I did:
> wget http://www.fdos.org/bootdisks/autogen/FDOEM.144.gz
> gunzip FDOEM.144.gz
> mkdir /tmp/floppy
> mount -t vfat -o loop FDOEM.144 /tmp/floppy
> Copied the flash files to /tmp/floppy
> umount /tmp/floppy
> mkisofs -o bootcd.iso -b FDOEM.144 FDOEM.144
> Can anyone help?

The file FDOEM.144 contains an image of a vfat file system - it is 1.4Mb 
- the size of a floppy disk.

The mount command mounts this image using the loop device - see the 
mount man page - and you then copy files to this file system

Once unmounted, the FDOEM.144 file now contains a file system with the 
files you've copied to it.

The mkisofs command line then creates a CD image iso9660 file - which 
contains one file - FDOEM.144

The -b option tells mkisofs to create a 'boot record' in the iso image 
which points to the FDOEM.144 file on the CD.

You then write this iso image to a CD.

When your machine is configured to boot from CD, it loads this file from 
CD and boots up whatever is in this image, which in this case is FreeDOS 
- see the mkisofs man page

James Pearson

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