Re: New Downloadable Version
Hello Thomas,
Thanks for the precise description. Since the ISO image for creating
both the DVD and USB-Sticks, finding a boot method that allows booting
in EFI mode in both scenarios is not easy. Also, DVDs use a different
sector size than USB HD storage, so the MBR containing a Partitioning
scheme for USB sticks, which SHOULD be ignored when using the Image as
DVD, may be wrongly interpreted by the computers firmware.
In the current setup, it looks like EFI boot of Knoppix (even with
"secure boot" enabled) works fine when the image is flashed to USB
HD/pen, but not in DVD mode. Some computers boot DVDs automatically in
the CSM (Bios) mode, and switch to EFI only for HDs. Knoppix will work
in these scenarios with the simple syslinux/syslinux.efi boot loader.
About grub.efi, I'm still undcided. It looks like the new Debian version
boots successfully in EFI+DVD-Mode with a signed grub-based boot loader,
but will this also work for a large range of EFI or non-EFI firmwares
with a 1:1 (dd) copy on USB flash pen? I am somewhat reluctant to
changing the syslinux boot system which is, as of now, still working
very well on very old computers, probably because of its simplicity and
reduced complexity.
About CD versions of Knoppix: Maintaining a CD parallel to a DVD version
is tricky. I'm thinking about reducing the size of the primary
compressed image KNOPPIX/KNOPPIX so that it fits on a CD together with
two kernels (32+64bit), and adding additional software by a second and
third image as aufs overlay, but this would cause a major rework of the
chroot-based build process, and I'm already way behind schedule for a
new public DVD-sized 8.6 release.
Regards
-Klaus Knopper
On 30.07.19, Thomas Schmitt wrote:
> Hi,
>
> Felix Miata wrote:
> > On Gigabyte Kaby Lake normally booted to UEFI, its F12 boot menu offers the 8.2
> > DVD disc in its Plextor DVD drive in both plain description:
> >
> > P3: PLEXTOR PX-891SAF (choice #2)
> >
> > and UEFI description:
> >
> > UEFI: PLEXTOR PX-891SAF (choice #11)
> >
> > two different options for the same disc. Selecting choice #2 produces a
> > familiar
> > Knoppix boot screen. Choosing #11 puts a non-blinking cursor on the screen
>
> That's a known problem of SYSLINUX EFI software with optical media.
> Afaik, it does not find the optical drive after having been started
> by the EFI firmware.
>
> Klaus Knopper hoped to circumvent this by putting a whole mini Linux
> into the EFI partition. It works for him on virtual machines (OVMF as
> EFI firmware, i guess). But obviously it does not work on most of the
> real iron EFI implementations. For me it does not even work with OVMF.
>
> This EFI-from-DVD problem is the reason why nearly all GNU/Linux ISOs
> are equipped with GRUB software for EFI. There are EFIs which boot
> SYSLINUX from USB stick but fail with GRUB. Rare, but credibly reported.
>
> In principle Knoppix could have different FAT filesystems for booting
> from optical media via El Torito and from hard-disk-like devices by
> the partition table. This would increase the ISO size and might be
> quite some work to make both EFI partitions deliver the same boot
> menu and boot result.
> Finally the firmware could go mad on such an unusual situation. YMMV.
>
>
> Whatever, the problem of JD is with USB stick i.e. a hard-disk-like
> storage device. Further he reports a GRUB prompt.
> So i suspect rather that the USB socket is not in the list of bootable
> devices of the firmware. But as stated: Why does GRUB then not boot
> the operating system for which it was most probably installed ?
>
>
> Have a nice day :)
>
> Thomas
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