Debian 11 not boot HP Workstation Z840

[Ghonz]

Hello, I have Customized Software Packed in Customized Debian 11 ISO File with no EFI support, normally i burn this iso file to usb or cd then install and boot the system and run. this was valid in different computer "Toshiba Laptop"  and also valid in virtual box until i tried to install this iso in the HP Workstation Z820 then tried Z840.

first notice HP workstation only boot from USB or CD (which have the customized Debian) when choosing only legacy boot and after all installation progresses the system not boot

after many search i found that the z840 workstation write boot to bios and my customized debian didnot do that, i tried normal debian and there is a message while installation asking to write uefi information and this make normal Debian boot successfully but my customized debian missing that. 

conclusion 

1- adding efi support to iso file which i don't know how 

2- make z840 boot after installation such as virtual box or some other kind computers. BIOS Setting??

i dont need to run second operating system just need the customized Debian using built in RAID10 Hardware in the Z840, i am using 4 x 4TB SATA HDD which seen 8TB storage by Debian, this configuration tested with normal Debian.

[Matt429]

Hello Ghonz,

If you press the F9 button during BIOS post and go into the Boot Menu, do you see your disk as a bootable option?

If not, can you go into the option that says "Boot From File"? If you're able to find your disk, you should be able to find and manually select your bootloader to boot.