(U)EFI, Grub partition missing all the sudden

[Axxon95]

I had Linux Mint(13,Cinnamon,x86_64,EFI) installed perfectly on it's own 40GB HDD. Windows and Linux are totally separated, I only have 1 HDD plugged in at one time. (I don't really know how EFI works, so I usually don't mess with it)
After a day or 2 of being on Windows for my gaming habit, I went to get back on Linux... and the EFI partition isn't showing up on the (Asus)EZ Mode, or on the boot override list, I can't get into grub at all.

Grub is messing up?
What should I do?

Edit 1: I tested gparted(latest_stable,EFI boot), and everything looks as it should on my HDD. GPT w/ 100meg Fat32 partition with the label "boot" and the rest of the 40GB split for Linux Mint and swap(during install, I left the sizes default).

[srs5694]

There is no such thing as a "(U)EFI Grub partition," and you've posted no information that makes me think a partition is missing. My suspicion is that your NVRAM's entry for GRUB has been lost, but it could be that the GRUB files are missing from the EFI System Partition (ESP) or that something else is wrong.

Background information:

EFI systems boot by using boot loader files stored on the ESP, which is a FAT partition, typically 100-200 MiB in size, and also typically the first partition on the first disk. It's legal to have more than one ESP, although this configuration is unusual enough that a lot of computer manufacturers clearly haven't tested it. Boot loader files usually reside in /EFI/{osname} subdirectories on this partition, as in /EFI/Microsoft for Windows or /EFI/linuxmint for Mint. The computer knows which of these files to use because information on them is stored in NVRAM. Some EFI implementations provide a boot manager menu that enables you to select which boot loader to use, but this built-in boot manager is often primitive.

If your NVRAM entry for Mint is missing, you can add it back by using the "efibootmgr" utility from an emergency boot in EFI mode. The command would look something like this:

Code: Select all

efibootmgr -c -l \\EFI\\linuxmint\\grubx64.efi -L Mint


Alternatively, you can add a boot manager such as rEFIt or rEFInd. (rEFIt has a number of problems on UEFI-based PCs. rEFInd is a fork of rEFIt that I created to address these problems and expand its capabilities generally.) Once installed, these programs will scan the usual locations for EFI boot loaders and present a boot menu with everything they find. rEFInd also has features that enable bypassing GRUB in favor of the kernel's EFI stub loader, which is a feature in 3.3.0 and later kernels that enables the kernel to function as its own boot loader. Unfortunately, Mint still uses 3.2.x kernels, so this feature isn't yet useful with Mint unless you compile your own kernel.

In the long run, adding rEFIt or rEFInd might or might not solve the problem; it's conceivable that whatever caused GRUB to be lost from the menu could happen to rEFIt/rEFInd, too. If the problem is that GRUB is installed on an ESP on the removable disk, though, installing rEFIt/rEFInd to the internal disk will make it less likely that this GRUB location will cause problems, since rEFIt/rEFInd scans for boot loaders at boot time rather than relying on NVRAM settings that might be changed for various reasons.

[Axxon95]

Well(the first impressions of what I seen), it's an (EFI)partition that grub was in and/or a part of, so I called it the grub partition.
I also could not put all of what happened into a title, so I didn't use a lot of words.
And by it "missing all the sudden", of course I meant missing on my (U)EFI Asus EZ bios screen(and on Advanced mode, boot override).
Slight miscommunication.
Anyways.

After about 10-15 minutes I stopped trying to boot and went back to Windows.
I have stuff to do, so when I get free time(hopefully soon), I'll check out what you commented about and report back.

BTW: I had rebooted multiple times(and after shutting my computer down for the night) while Linux Mint was still working, and it still showed the EFI boot partition(on the (U)EFI bios screen).
Like as if you had a LiveUSB with EFI, you'd see UEFI: SanDisk as well as SanDisk on my bios, in addition, when I override boot to my HDD it says it can't find a boot loader(or something to that extent, I'll edit this after I try again to get the correct wording) and doesn't boot(I assume, not seeing grub...)
Just for some reason after a few days its just not showing.
In addition, on gparted live(Edit 1 on first post), it still showed the same amount of space used in the EFI(Fat32) boot partition as it did before.