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michaelslack 02-28-2013 09:58 PM

samsung/gdisk/uefi booting anxiety
 
I'm in a similar situation to rkelsen: http://www.linuxquestions.org/questi...2/#post4888222 but with some differences.

I've acquired a samsung hybrid ultrabook/tablet (XE700T1C-A02AU, the Australian build of the so-called smart pc pro), with win8 pre-installed...of course. My original plan was to keep win8 there (at least for the time being) but dual-boot it with 32-bit slackware.

I shrunk the win8 partition, created a new partition for slackware and a separate one for swap, all from inside win8.

Next I looked into booting the install disk. Under the advanced boot settings in the uefi setup there are 3 choices: uefi only, csm (compatability support module, i.e. legacy) only or both.

Choosing ``both uefi and csm'' (also works under csm-only of course), I was able to boot up the install disk, after changing the boot order priority. I used mkswap, ran setup and managed to perform all of the installation properly except lilo (I'd seen warnings about it at slackdocs) and so created a USB boot stick.

Now it boots and works fine, but I am dependent on the bootstick. It boots under csm/legacy, not uefi. If I leave the boot setup at ``uefi and csm'' I have to have the bootstick in there or win8 boots *and* the boot setup forgets that setting. If I set it to ``csm only'' and I forget to insert the bootstick, it just opens up the uefi setup menu (reminding me to insert the bootstick and reboot). This is fine so long as I don't want to boot win8, but it is still far from ideal.

If I were happy to get slackware to boot with uefi, the info in some earlier posts would probably get me out of trouble. However as Pat noted:
Quote:

Originally Posted by volkerdi (Post 4889551)
Yes. This is just information for the people who want to brick their Samsung laptops now.

So it may be a bit dangerous for me to try to boot into slackware using uefi, although I have seen on some other webpages that not *all* samsung laptops are problematic, only some. But there is sufficient confusion to convince me to remain cautious and hold off from doing this for now.

So it would seem I should be booting under csm, i.e. convert the disk from GPT to MBR. It is not clear (to me at least) how to implement this. There is some good general info at rodsbooks.com/gdisk/mbr2gpt.html#gpt2mbr but it is still a bit unclear what I need to do in my situation. I would like to keep the win8 there if I can (there is a samsung win8 app that does mathematical handwriting recognition!!...no open source version exists AFAIK). Unfortunately, it seems I can't make a ``recovery disk''; there are some hidden and recovery partitions on the disk which need to stay there, presumably under GPT, for the ``power-up-with-volume-up-pressed'' recovery procedure to work. I don't know enough about it but I think that even if I use win8 to create a backup or even a factory image, if I wipe the disk clean there may be no (easy) way to recover my (samsung-specific, with custom e.g wacom tweaks) win8. I could perhaps keep the hidden/recovery partitions there even if I convert from GPT to MGR, although I don't know how exactly (and maybe this is pointless anyway?).

As far as I can tell, I should use gdisk (from inside slackware, as root) to change the disk from GPT to MBR, using the `r' command to take me to the recovery/transformation menu. Then I can either use `g' to convert it to MBR, or maybe even `h' to create a hybrid GPT/MBR disk, although this looks *way* beyond my comfort zone. Since there are more than 4 partitions, some will be made logical so long as there is an empty sector (or something) at the beginning of the partition. So using `g' may mean I lose some of these. I can perhaps keep them all using `h'. I don't know.

I am suitably unsure that I thought I would try to ask someone who actually knows what they are doing before I blunder in and possibly ruin everything. My apologies if I have omitted any vital info on this, my first LQ post.

Thanks in advance,

Michael

volkerdi 02-28-2013 11:17 PM

I don't think there's going to be any way to convert from GPT to MBR without wiping the disk of all data, and I also think that you really don't want to do that anyway. I'd suggest waiting until the next kernels come along in -current since those will be Samsung UEFI safe, and then trying to use those along with elilo. If that works, you can look into a boot manager like rEFIt or rEFInd for dual booting.

michaelslack 03-01-2013 12:17 AM

Thanks Pat for the quick reply. I'll wait for those new kernels and give elilo a go. In the meantime I'll try and read up a little more on (u)efi booting.

Cheers,

Michael

comet.berkeley 03-02-2013 09:05 PM

Try to create Windows recovery media (DVD/USB).

I know from restoring Windows 7 from an Acer system that 3 disk partitions are created/populated including the recovery partition, the boot partition and the main c: drive partition.

Hopefully Windows 8 recovery will also restore all the original disk partitions.

Maybe check the Samsung website/forums for details?

And be sure to backup any other data/programs that you created/installed as well.

michaelslack 03-03-2013 03:40 AM

Quote:

Originally Posted by comet.berkeley (Post 4903451)
Hopefully Windows 8 recovery will also restore all the original disk partitions.

Yes, "Hopefully" being the operative word.

I've since managed to create a ``factory image boot disk'' on a usb stick. However it is not clear if that will work or not if the disk is totally wiped.

When shipped it has 5 partitions:

1. windows RE (recovery environment?) (499MB)
2. EFI system partition (300MB)
3. Installed Windows system (the rest)
4. Samsung Recovery 1 (12 GB)
5. Samsung Recovery 2 (1 GB)

When I boot the factory image USB (with the disk still intact of course) it goes into the Recovery program as it should. I'm just not sure if this needs any of those other original partitions to be there for it to do so.

You're right though, this is not a slackware question now, rather a samsung (maybe also uefi?) one. I'll check out some other forums, although straight googling was not very fruitful.

Cheers,

Michael

FlorinU 07-02-2013 11:15 PM

Quote:

Originally Posted by michaelslack (Post 4903575)
Yes, "Hopefully" being the operative word.

I've since managed to create a ``factory image boot disk'' on a usb stick. However it is not clear if that will work or not if the disk is totally wiped.

When shipped it has 5 partitions:

1. windows RE (recovery environment?) (499MB)
2. EFI system partition (300MB)
3. Installed Windows system (the rest)
4. Samsung Recovery 1 (12 GB)
5. Samsung Recovery 2 (1 GB)

When I boot the factory image USB (with the disk still intact of course) it goes into the Recovery program as it should. I'm just not sure if this needs any of those other original partitions to be there for it to do so.

You're right though, this is not a slackware question now, rather a samsung (maybe also uefi?) one. I'll check out some other forums, although straight googling was not very fruitful.

Cheers,

Michael

Hello Michael,
Can I have your image backup? I have make backup to mine but only for partition and don't work any more wen I restore it. Now I stuck with Ubuntu and don't work as I want.
Please share that image. Thank you.


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