Here are my detailed tests with - debian-13.5.0-amd64-netinst.iso - grml-full-2026.04-amd64.iso - ubuntu-26.04-desktop-amd64.iso - ubuntu-26.04-live-server-amd64.iso
================================================================================ Test Debian 13.5 netinst - debian-13.5.0-amd64-netinst.iso mounted as virtual media (ISO) via IPMI This ISO then shows up as UEFI: ATEN Virtual CDROM YSOJ and boots in UEFI mode - debian-13.5.0-amd64-netinst.iso written via dd to USB stick This is shown after written the ISO to stick on my laptop: $ blkid /dev/sda1: BLOCK_SIZE="2048" UUID="2026-05-16-10-12-45-00" LABEL="Debian 13.5.0 amd64 n" TYPE="iso9660" PTUUID="605e893e" PTTYPE="dos" PARTUUID="605e893e-01" /dev/sda2: SEC_TYPE="msdos" UUID="DEB0-0001" BLOCK_SIZE="512" TYPE="vfat" PARTUUID="605e893e-02" $ fdisk -l /dev/sda Disk /dev/sda: 476.94 GiB, 512110190592 bytes, 1000215216 sectors Disk model: TS512GESD310C Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disklabel type: dos Disk identifier: 0x605e893e Device Boot Start End Sectors Size Id Type /dev/sda1 * 0 1546239 1546240 755M 0 Empty /dev/sda2 4112 11311 7200 3.5M ef EFI (FAT-12/16/32) This USB stick does not show up on the Supermicro server in the boot menu list (after pressing F11) -------- If I enter the BIOS and change the BIOS settings to "Legacy USB Support" selectedOption="Enabled" "Boot Mode Select" selectedOption="DUAL" (means UEFI aand legacy) "LEGACY to EFI Support" selectedOption="Enabled" the USB stick boots in legacy mode Inside the BIOS this USB stick is only shown in the Boot option list if Boot mode is legacy or DUAL, not if I choose there UEFI. ================================================================================ Now doing the same tests with different ISOs GRML test ========= writing grml-full-2026.04-amd64.iso via dd to USB stick $ fdisk -l grml-full-2026.04-amd64.iso Disk grml-full-2026.04-amd64.iso: 1.03 GiB, 1100675072 bytes, 2149756 sectors Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disklabel type: dos Disk identifier: 0x00000000 $ blkid /dev/sda: BLOCK_SIZE="2048" UUID="2026-04-29-10-30-00-00" LABEL="grml-full-amd64 2026.04" TYPE="iso9660" PTTYPE="dos" In boot menu list it shows as UEFI OS (< and description of USB stick>) and boots fine into linux with UEFI mode ================================================================================ Now doing the same tests with different ISOs Test Ubuntu desktop ISO ======================= ubuntu-26.04-desktop-amd64.iso via dd to USB stick $ fdisk -l ubuntu-26.04-desktop-amd64.iso Disk ubuntu-26.04-desktop-amd64.iso: 6.07 GiB, 6518974464 bytes, 12732372 sectors Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disklabel type: gpt Disk identifier: 2FDF80BE-E145-40C5-AA53-61A53AB5282E Device Start End Sectors Size Type ubuntu-26.04-desktop-amd64.iso1 64 12721411 12721348 6.1G Microsoft basic data ubuntu-26.04-desktop-amd64.iso2 12721412 12731707 10296 5M EFI System ubuntu-26.04-desktop-amd64.iso3 12731708 12732307 600 300K Microsoft basic data $ blkid /dev/sda2: SEC_TYPE="msdos" LABEL_FATBOOT="ESP" LABEL="ESP" UUID="172C-47F7" BLOCK_SIZE="512" TYPE="vfat" PARTLABEL="Appended2" PARTUUID="2fdf80be-e145-40c5-aa51-61a53ab5282e" /dev/sda3: PARTLABEL="Gap1" PARTUUID="2fdf80be-e145-40c5-aa50-61a53ab5282e" /dev/sda1: BLOCK_SIZE="2048" UUID="2026-04-23-02-18-51-00" LABEL="Ubuntu 26.04 amd64" TYPE="iso9660" PARTLABEL="ISO9660" PARTUUID="2fdf80be-e145-40c5-aa52-61a53ab5282e" In boot menu list it shows as UEFI OS (< and description of USB stick>) and boots kernel but no grpahics (maybe because it's a server, nodesktop) ================================================================================ Now doing the same tests with different ISOs Test Ubuntu server ISO ====================== ubuntu-26.04-live-server-amd64.iso via dd to USB stick $ gdisk -l /dev/sda GPT fdisk (gdisk) version 1.0.10 Partition table scan: MBR: protective BSD: not present APM: not present GPT: present Found valid GPT with protective MBR; using GPT. Disk /dev/sda: 1000215216 sectors, 476.9 GiB Model: TS512GESD310C Sector size (logical/physical): 512/512 bytes Disk identifier (GUID): 18602C22-4F22-4F06-9B9F-D3276CFC7EAB Partition table holds up to 248 entries Main partition table begins at sector 2 and ends at sector 63 First usable sector is 64, last usable sector is 5700324 Partitions will be aligned on 8-sector boundaries Total free space is 1 sectors (512 bytes) Number Start (sector) End (sector) Size Code Name 1 64 5689427 2.7 GiB 0700 ISO9660 2 5689428 5699723 5.0 MiB EF00 Appended2 3 5699724 5700323 300.0 KiB 0700 Gap1 $ blkdid /dev/sda2: SEC_TYPE="msdos" LABEL_FATBOOT="ESP" LABEL="ESP" UUID="F211-6A7E" BLOCK_SIZE="512" TYPE="vfat" PARTLABEL="Appended2" PARTUUID="18602c22-4f22-4f06-9b9d-d3276cfc7eab" /dev/sda3: PARTLABEL="Gap1" PARTUUID="18602c22-4f22-4f06-9b9c-d3276cfc7eab" /dev/sda1: BLOCK_SIZE="2048" UUID="2026-04-20-18-23-36-00" LABEL="Ubuntu-Server 26.04 amd64" TYPE="iso9660" PARTLABEL="ISO9660" PARTUUID="18602c22-4f22-4f06-9b9e-d3276cfc7eab" $ fdisk -l ubuntu-26.04-live-server-amd64.iso Disk ubuntu-26.04-live-server-amd64.iso: 2.72 GiB, 2918598656 bytes, 5700388 sectors Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disklabel type: gpt Disk identifier: 18602C22-4F22-4F06-9B9F-D3276CFC7EAB Device Start End Sectors Size Type ubuntu-26.04-live-server-amd64.iso1 64 5689427 5689364 2.7G Microsoft basic data ubuntu-26.04-live-server-amd64.iso2 5689428 5699723 10296 5M EFI System ubuntu-26.04-live-server-amd64.iso3 5699724 5700323 600 300K Microsoft basic data In boot menu list it shows as UEFI OS (< and description of USB stick>) and boots fine into linux with UEFI mode -- reagrds Thomas
