Re: changing from BIOS to GPT
Gary Dale a écrit :
> I have a computer that was set up with an the older style partition
> table and wanted to convert it to GPT.
May I ask why ?
> Since the first partition started
> at 2048, I figured this wouldn't be a problem. Just use gdisk to write a
> new partition table after stealing some space from swap for an EFI boot
> partition. Then reconfigure grub...
If you changed the disk format you must reinstall GRUB's boot loader
with grub-install so that the new core image includes the GPT module,
not just reconfigure it with update-grub.
>From the subject of your post, you seem to be confusing the boot mode
and the disk format.
The boot mode is either BIOS/legacy or (U)EFI.
The disk format is either MBR/MSDOS or GPT.
Linux and GRUB accept any combination, provided the proper version of
GRUB is installed (grub-pc for BIOS/legacy, grub-efi-amd64 for UEFI).
> The HD originally had all 250G dedicated to Windows 7/Pro 64 (the way I
> got it - not my choice). I shrunk that down to the smallest Windows
> would allow - 137G - and created new Linux and Swap partitions that I
> installed Jessie to.
Note that unlike GRUB and Linux, Windows 7 can only boot from a GPT disk
in UEFI mode or from a MBR disk in BIOS mode. If you change the
partition table format, then Windows won't be able to boot any more. If
you were able to boot Windows before converting the disk to GPT, then
the boot mode was BIOS/legacy with grub-pc.
> Now I don't even to get a grub rescue prompt. I've tried reinstalling
> grub in a chroot after booting with system rescue cd but that didn't
> work. I've reinstalled grub to /dev/sda but again without success.
> Update-grub sees the partitions but doesn't give me a bootable system.
>
> BTW: Grub is the grub-efi-amd64 package.
Was it grub-efi-amd64 already before converting the disk to GPT or did
you install it afterwards, replacing grub-pc ?
If, the system was previously booted from grub-efi-amd64 in UEFI mode,
then an EFI system partition must have been already present and mounted
on /boot/efi. This partition is mandatory for booting in UEFI mode.
Please clarify the original situation and changes done.
Arno gave you a tip about the default EFI boot loader. The Debian
installer is also bootable in EFI mode.
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