#32 Boot From CD


Can Bochs Boot from a CDRom or a CDRom Image? If So
what bochsrc settings are needed. I am using bochs on
a Windows 2000 machine. I can read a physical CDRom
disk and boot from image or Physical floppy as well as
Hard drive image. I would like to be able to boot
from CD.


  • stuart blake tener

    Logged In: YES

    I would agree, booting from CD-ROM would make less the pain
    of loading an OS which by todays standards mostly boot from

    The future holds the ability to boot from DVD-ROM (as SuSE
    Linux does). This is much needed functionality,
    and will allow testing of many other OSes once written.

    This is an important feature.

  • Bryce Denney

    Bryce Denney - 2001-09-16

    Logged In: YES

    At the moment Bochs cannot boot from a CD, on any operating
    system. The spec for the bootable CDROM format is called El
    Torito, and we have a copy at

    The basic idea is that the BIOS must recognize the CDROM
    device and make the boot code available using INT 13, so
    that it can be accessed somewhat like a disk drive. To add
    this capability to Bochs, probably all the work would be
    done in bios/rombios.c. It sounds like a perfect project
    for someone....

    Compiling a new BIOS requires a compiler called bcc, an x86
    assembler called as86, and a linker called ld86. I'll help
    anyone get these tools going, if they want to work on the

  • Bryce Denney

    Bryce Denney - 2002-03-06

    Logged In: YES

    Christophe Bothamy has added El Torito support in rombios.c,
    which allows Bochs to boot cdroms. To use this, you must
    set the rombios line in your bochsrc to point to
    BIOS-bochs-eltorito, and the boot line must be set to
    "cdrom". These changes will be included in version 1.4.
    Example bochsrc lines are:
    romimage: file=bios/BIOS-bochs-eltorito,
    boot: cdrom

    In recent emails Christophe has described what works and
    what doesn't. Here's a summary:
    - Bochs can boot from a disc or from an iso image.
    - It should work on all known kinds of Linuxes, win95 and
    win98, which use floppy images written on cd. El-Torito
    specs define a "floppy emulation" for booting such cds,
    using standard bios floppy functions.
    - not all of El Torito is supported. Win2k and presumably
    WinXP boot require other types of emulation and are not
    currently implemented.

    I hope Christophe will correct this if it's wrong. :)

    To Christophe, who now owns this feature request: Please
    close this when you think the cdrom boot code is ready for
    the 1.4 release. For the release we should document what
    works and what doesn't, perhaps in the CHANGES file or in
    the docbook documentation.

  • Christophe Bothamy

    Logged In: YES

    The default BIOS now can boot real cds, or iso files.
    use "boot: cdrom" in the configuration file.

    Everything but "hard-disk emulation" and "int13 AX in
    (4A, 4B, 4C)" is implemented.

    So this bootable cds should work :
    - floppy emulation : linuxes win98
    - direct cdrom access : win2k winXP

    So I'm closing this request now.

    However winXP and win2k fail during the NTDETECT process.
    This probably won't be fixed for 1.4, sorry.
    I am opening a bug report for this.

  • Bryce Denney

    Bryce Denney - 2002-03-12

    Logged In: YES

    GREAT JOB!!!!!!

  • Nobody/Anonymous

    Logged In: NO

    I have an workaround idea which may solve your problem (it solved
    mine): Make a boot floppy containing lilo or grub, configured to boot the
    cd, make an image of it and boot from the floppy image
    The lilo or grub should then be able to detect and boot the cd


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