I can report progress: There are new compressed image files to be extracted and cloned to USB drives for UEFI and BIOS mode, that can boot also with secure boot in a computer updated to squash the boothole bug.
You find these image files at phillw.net/isos/linux-tools/uefi-n-bios, where you also find files with the corresponding md5sums.
These compressed image files are similar to the previous ones made recently, but the boot system is made by installing Ubuntu Focal from the current daily iso files (post 20.04.1 LTS) with up to date program packages, that include secure boot shims for the relevant components. This works also with a Lenovo V130, that refuses to boot USB boot drives cloned from current daily Groovy iso files in UEFI mode.
There is still a problem with usb-pack-efi and mkusb-dus to make persistent live drives that work with secure boot. It may take some time until I can fix it. Until then, secure boot must be turned off for them to run. The problem is that vital parts of the old tools have an old signature in the shims and lack the fix against the boothole bug.
Fortunately for users, who want a convenient tool with a graphical user interface to make persistent live drives, mkusb-plug is still working, where cloned drives are working [with secure boot], that is in most computers.
I think the proposed updates of the LTS release beyond the first point release are not very adventurous, and should not cause too many hiccups. Anyway, I am interested in your opinion about that.
- mkusb_grub-boot-template-for-uefi-n-bios_fat32_4GB_use-in-wins_2020-09-07.img.xz
This image is small, ~ 7.5 MB, and expands to slightly less than 4 GB in order to fit in a 4 GB USB pendrive or memory card.
When extracted, you mount the first partition, which is labeled 'ISODEVICE' and has the file system FAT32 (shown as 'vfat' by Ubuntu), and copy an Ubuntu family iso file [into this first partition 'ISODEVICE']. Rename the file to ubuntu.iso.
Code:
$ lsblk -fm /dev/sdc
NAME FSTYPE LABEL UUID MOUNTPOINT SIZE OWNER GROUP MODE
sdc 29,1G root disk brw-rw----
├─sdc1 vfat ISODEVICE 0338-85F9 /media/sudodus/ISODEVICE 3,4G root disk brw-rw----
├─sdc2 1M root disk brw-rw----
├─sdc3 vfat ESP 1841-531C 64M root disk brw-rw----
└─sdc4 ext4 usb-boot 733906cb-a2c4-47f2-8fd0-a2a0bdef765a /media/sudodus/usb-boot 128M root disk brw-rw----
$ ls -lh /media/sududus/ISODEVICE
total 1,8G
-rw-r--r-- 1 sudodus sudodus 1,8G sep 7 21:51 ubuntu.iso
I have tested iso files of 20.04.1 LTS as well as current daily Groovy, and I can boot live systems in BIOS mode as well as in UEFI mode also with secure boot [in a computer updated to squash the boothole bug].
If you have a bigger drive, you can use gparted to create new partition with the label 'casper-rw' or 'writable' and the file system ext4 and get a persistent live drive. You can also create a data partition with the file system NTFS to store data and exchange data with current versions of WIndows 10, that can manage more than one partition in USB drives. See the attached screenshots. (Older versions of Windows can only manage partition #1, and this is preconfigured as 'ISODEVICE' with the file system FAT32.)
- dd_unb_ubuntu-20.04_15GB_2020-09-07_with-proposed.img.xz
This image contains a whole installed and fully updated & upgraded Ubuntu 20.04.1 LTS system. The compressed image is 1.6 MB (1.5 MiB), smaller than the iso file because several files are removed near the end of the installation, for example language files. The language selected is US English, but you can add another language, and you can install whatever drivers and program packages, when your system is running.
When extracted, this installed Ubuntu system expands to slightly less than 16 GB in order to o fit in a 16 GB USB pendrive or memory card. If you have a bigger drive, you can use gparted to grow the root partition to use the whole drive.
See also these links (which should soon be updated with the current compressed image files),
help.ubuntu.com/community/Installation/UEFI-and-BIOS
BIOS/UEFI Template Image for Booting ISO Files