Re: Debian Installer use GPT partition but Uboot does not recognize it ?
I then installed an internal 2.5" hard drive inside the enclosure of
the Open-Rd and tried to install debian on it using the same
I think the 2.5" HDD had an EFI partition to start with.
If the GPT table was already there then afaict that would explain why you ended up with GPT at the end. Afaict the debian installer does not change the partition table types of drives (at least not unless expliticly told to)
I also connected the 2.5" drive to a regular PC and did a gptsync.
Then Uboot can see the partitions but the boot parition was empty
Be aware that due to the way the hybrid partition table works the first partition on the drive will not be correctly represented. On intel macs (the origin of the hybrid format) this doesn't usually matter as apple tools always put an efi system partition as the first partition.
If you just want to get debian installed using that drive and it doesn't have any data you want to keep on it I would suggest zeroing out the drive first. That way d-i will start with a clean slate.