I've just encountered the weirdest problem and so far, internet searches don't help ... so: (apologies for the saga ... I think it helps though)

I recently purchased a LENOVO Thinkpad Edge E540 for my daughter. As a linux-only family I really wanted to nuke the windows partition, but my husband had one piece of software that was not running properly under wine or linux ...
SO,
* I shrunk the windows partition
* installed MAGEIA on the remaining space
These were both successful, and the only drawback was that if you needed to boot to WINDOWS you had to go into the BIOS and set it back to boot in both UEFI and LEGACY mode. Inconvenient, but it solved the minor need to access windows.

Then, after the last boot into windows (my husband needed to access his propriety software) windows decided to do some kind of update. We cared less about the update, and so I said just *hit the power button and reboot into the bios* (yes not the most sensible thing ... but hey, we didn't care about the windows side much). After a couple of tries, (weird! but my husband was driving the keyboard) we get into the BIOS and change back to LEGACY boot only.
REBOOT time ... and the system gets stuck.

It was really odd - I couldn't see anything immediately wrong (log in as root, look at system logs etc.) and then something twigged me to look at the partition table. IT HAD BEEN CHANGED TO A GPT !!!!! All the linux partitions were labelled as microsoft basic data partition types. WHAT THE #¤%#&¤!!!!

Has anyone seen this kind of sneaky update before?

Does anyone have a (non destructive) way of restoring the MBR table? (Fortunately my daughter has very little data on it, and in rescue mode I can still see all the files etc.)

On principal, I do not like being dictated by the OS on how I set up my system, esp. the way it was done here. However, if the best option really is to convert it properly to a GPT : how should I go about doing this?

Anyway, all comments and opinions as well as help are greatly appreciated.

It is possible to reinstall Linux and the it uses GPT.

Yes I can, and I will do that as a "nothing else will work option". It just takes time to do that.

However, I'm still miffed it happened at all!

Sounds very suss to me. Are we to presume this is Win8(.1) and it still boots ok ?.

For Linux to boot gpt on BIOS, the bootloader will need to be re-installed into a special BIOS boot partition. And of course the partition type for Linux partition(s) would need to change.
All of this, and the conversion back to MBR can be done by gdisk. Use at your peril - gdisk will work, but may not retain (all) your data, or worse may do what you ask, not necessarily what you thought you asked for.

Note my sigline.

Thanks!

I haven't tried booting Windows again (and yes, it's Win8(.1)). I'll give that a go and see what happens. When you say "suss"
do you mean the partition table being changed? I've never come across anything like it before. I asked my colleagues (I work
in HPC), and they've not encountered it either.

Up to now, what I found on the net said exactly what you mentioned ... you can restore MBR but it will probably not work
quite right. There are a few guidelines for installing linux under GPT and so far it sounds like my best bet is to reinstall.

If your windows 8 was pre-installed on the computer, it was likely installed using UEFI/GPT and you would need to install Mageia using UEFI/GPT or you will get...well, you've experiened what happens. If you are using the Legacy BIOS, you need a very small BIOS Boot partition to use GPT. If you are using UEFI, you should have a FAT32 partition near the beginning of the drive, 200-500MB in size which should contain both the windows and Linux efi files.

You should not have to make changes in the BIOS to boot either.
It might be that not doing a proper shutdown of windows is part of the problem. Windows 8 usually doesn't shut down but hibernates which causes problems also.

Hi,

Have you considered a Windows virtual machine? This way your main OS is Linux and whenever you need windows, just fire up the VM without having to go through all that trouble.

The Arch wiki has great instructions on how to install GRUB on a UEFI system: https://wiki.archlinux.org/index.php/GRUB
It seems that GRUB can't detect other OSes in UEFI mode, so you have to manually add Windows to the boot menu. The link above has step-by step instructions on how to do that.

Note: I have a UEFI laptop, and mine always hangs for about 2 seconds before it will let me do any selections. I don't know if it's just my laptop, or UEFI in general, but if it happens to you it shouldn't be a problem.

Hope this helps!

Thanks for the replies up to now - I've been distracted by my paying job, and hope to attempt the
last suggestion this weekend. (thanks maples)


YANCEK : hmm ... your comment got me wondering that I might have created the partition confusion in the
first place when I installed Mageia.

erik2282: worth a try - though I thought you needed an install disk to do this. Anyway, I'll look into it.

verayh,

You do not need a separate disk for a Virtual Machine, though you can put the virtual machine on a seperate disk if you wanted to. It uses space you allocate to the VM. I personally dislike dualbooting, but thats just me.

Installation Disk...

The internet tells me you can download a Windows 8 installation disk file from inside your present Windows 8 installation.

The license for the OS allows you to use it on the same system to which it is liscensed in any way you wish and re-install it as you will or need.

It might be good to have as a fail-safe even if you don't use it.

http://www.howtogeek.com/186775/how-...media-legally/

verayh,

As recommended above, first make sure that all personal data is backed up to an external drive.

Disable both Fast Boot and Secure Boot in W8.1.

You can check your existing partitions by booting from a Gparted DVD or USB flash drive:
http://gparted.org/

You must use UEFI (not Legacy), and GPT, plus a 64 bit version of a Linux OS (Mageia or other).

For further info, look at this dual-boot with W8 and Ubuntu 14.04:
http://www.dedoimedo.com/computers/d...-8-ubuntu.html

Good luck.

https://www.virtualbox.org/wiki/Downloads

In case you want to try going this way instead, here is the link to downloading Virtual Box. I use it for my Windows 7 Pro VM and a few other Linux distros. Works great, way better than dual-booting if you ask me.