[syslinux] syslinux mkisofs hard-disk-boot isohybrid

[Pascal]

Le mercredi 21 décembre 2016, Ady Ady via Syslinux <syslinux at zytor.com> a
écrit :

>
> > Hi,
> >
> > Pascal wrote:
> > > mkisofs -o core.iso -b boot/core.img -c boot/boot.cat -hard-disk-boot
> core/
> > > my iso image is ok with qemu on bios and uefi,
> >
> > Astounding. As CD-ROM this is not supposed to work with UEFI unless the
> > firmware emulates BIOS. What particular UEFI firmware did you use ?


 https://www.kraxel.org/repos/jenkins/edk2/

>
> > >  and with qemu as hard disk on uefi but not on bios.
> >
> > That's even more astounding. The UEFI would have to look into the ISO
> 9660
> > filesystem or interpret the El Torito boot info prepared for BIOS.
>
>
> I think that "in qemu as hard disk" means that he is not booting it as
> CD-ROM, so no iso9660 in this case; but I could be misinterpreting the
> words.


the iso image is used as a hard disk image like this :
qemu -hda core.iso -bios uefi.fd

uefi.fd (pure) come from https://www.kraxel.org/repos/jenkins/edk2/


> >
> >
> > > isohybrid: core.iso: unexpected boot catalogue parameters
> >
> > That's because ISOLINUX boot images are binary programs which get
> registered
> > in the El Torito catalog as "no emulation" images. Your core.img is
> registered
> > (by option -hard-disk-boot) as "hard disk emulation" image.
> >
> > http://git.zytor.com/syslinux/syslinux.git/tree/utils/isohybrid.c
> > bails out in line 526, because variable de_media is 4 and not 0.


rewriting error message ?


> >
> > For BIOS booting from CD-ROM you need to use "isolinux.bin" as boot image
> > which you give to mkisofs via option -b. Instead of
> >
>
>
> @Thomas, please remember that, if we forget for a moment about other
> constraints and conditions (e.g. isohybrid, UEFI, whatever), a CD-ROM
> using "El Torito hard disk emulation" can still be bootable in BIOS
> mode.


:-) and do you know how to do ? or is it better to stop with hard-disk-boot
and go on isolinux.bin ?


>
> >   -hard-disk-boot
> >
> > you have to use
> >
> >    -no-emul-boot -boot-load-size 4 -boot-info-table
> >
> > See http://www.syslinux.org/wiki/index.php?title=ISOLINUX
> >
> > For UEFI from CDROM you need a FAT filesystem image with EFI boot files
> > like  /efi/boot/bootx64.efi  in it. Note that the EFI boot software of
> > SYSLINUX does not boot from CD-ROM, even if properly wrapped and
> announced
> > in El Torito. ISOs which work from CD-ROM mostly use GRUB-equipped FAT
> > images for UEFI.
> >
> > The UEFI boot image has to be announced in El Torito by the ISO producer
> > program. See options
> >
> >   -e isolinux/efiboot.img -no-emul-boot
> >
> > or
> >
> >   -eltorito-platform 0xEF -eltorito-boot isolinux/efiboot.img
> -no-emul-boot
> >
> > in
> >   http://www.syslinux.org/wiki/index.php?title=Isohybrid#UEFI
> > ("isolinux/efiboot.img" is the FAT image with content from other boot
> loader
> > projects or an EFI-ready operating system kernel.)
> >
> > Such an ISO is then ready for being processed by isohybrid, so that
> > it afterwards has MBR BIOS x86 boot code and partition tables pointing
> > to the FAT filesystem for UEFI.
> >
> >
> > Have a nice day :)
> >
> > Thomas
> >
>
>
> Also, there is at least one more method to boot optical media in UEFI
> mode: using UDF. Unfortunately, this doesn't change the fact that
> syslinux.efi v.6.03 cannot boot optical media in UEFI mode (in spite of
> Peter hinting about such capabilities in some email in the past).
>
> Regards,
> Ady.
>
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