Bug#1137930: debian netinst ISO does not boot in UEFI mode on Supermicro server

Package: debian-cd
Severity: minor


When I write the image debian-13.5.0-amd64-netinst.iso via dd to an
USB stick and boot the Supermicro server it only boots in
legacy mode. If I force UEFI in the BIOS the USB stick is not
detected at all.

Booting in UEFI mode works, if I boot from a virtual media via IPMI
(means a virtual CD).


Hardware:
Supermicro Server 	AS -8125GS-TNHR
Mainboard: 	H13DSG-O-CPU-D
Firmware 01.08.02
Redfish Version 	1.22.2
BIOS Firmware Version 	BIOS Date: 03/06/2026 Ver 3.9

Bios settings (force UEFI):

"Legacy USB Support" selectedOption="Disabled
"Boot Mode Select" selectedOption="UEFI"
"LEGACY to EFI Support" selectedOption="Enabled"



Supermicro says in two FAQs for different servers, that you must
"format your USB drive in GPT partition scheme for UEFI."

See
https://www.supermicro.com/en/support/faqs/faq.php?faq=22149
and
https://www.supermicro.com/en/support/faqs/faq.php?faq=41748


I will add more detailed tests with other ISOs, after I gott he bug number.