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m1ngsheng
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PostPosted: Wed May 06, 2015 5:25 pm    Post subject: "Operation System not found", XPS 13, By the Book Reply with quote

Reaching out for ideas y'all. I (believe) I followed the handbook installation by the book - pretty much no deviation. At the "end" where system is rebooted, I sadly found myself with "Operation System not found". And every boot after that - unless of course I boot from my USB stick.

Searching here and web I really don't see a concrete direction to try. Some posts mention EFI vs. BIOS system partition. I chose BIOS 'cuz honestly I've not used EFI on any of my systems in the past and figured why complicate the install. Mentioning this in case this actually is the issue. Also honestly: I'm not sure how to know whether XPS 13 must use EFI if that is the case.

I suppose a bonus request is tip/s how I might avoid redoing install from scratch in case I have a faulty partition setup.

Thanks sincerely,
Rjae

P.S. I guess I should mention that I did the install with the latest bits from Gentoo...but I'm thinking version really won't matter at all here.
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irafiral
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PostPosted: Wed May 06, 2015 6:27 pm    Post subject: Reply with quote

m1ngsheng,

"Operation System not found" is a well known message for me, as I own a xps17 and have had this problen too.

The message says me, that your drive is gpt partitioned and you are trying to boot in legacy (pc) mode (like me some years ago).

I guess no faulty partition setup ... the magic is to a setup a hybrid MBR (with gdisk).

For grub you need additional a very small partition (128KB are enough) with type EF02 which can reside within the first mb of your drive after the gpt stuff.

No need to use efi;)
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m1ngsheng
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PostPosted: Wed May 06, 2015 6:43 pm    Post subject: Reply with quote

Thanks irafiral! I don't know the technical carry-through on what you offered but sounds like once I research the steps it will solve problem.

Since I used all my drive space for existing partition layout, I suspect I'll need to "redo" one of the partitions. Guess other option - which ain't bad - is I could create the EF02 you mention on my USB stick.
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irafiral
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PostPosted: Wed May 06, 2015 6:53 pm    Post subject: Reply with quote

I guess sector 34 up to sector 2047 are unused.
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m1ngsheng
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PostPosted: Wed May 06, 2015 7:26 pm    Post subject: Reply with quote

Thanks. I'll give this a shot maybe this weekend...and will post results here.
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NeddySeagoon
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PostPosted: Wed May 06, 2015 7:34 pm    Post subject: Reply with quote

m1ngsheng,

With a brain dead BIOS and a GPT partitioned disk, the BIOS will attempt to find the bootable flag an the 'protective' MSDOS partition table that is provided free with GPT.
As its not set, you get this error from your BIOS and in won't load your boot loader.

The fix is to set the bootable flag on the MSDOS partition.
Boot your live media and run
Code:
fdisk -t dos /dev/...

Only set the bootable flag. Do not attempt to make any other changes to this (fake) partition table.

This will get you on to your next Gentoo learning experience.
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Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail.
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m1ngsheng
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PostPosted: Thu May 07, 2015 11:18 am    Post subject: Reply with quote

I may have spotted an unintentional mistake during installation. Not knowing I had an EFI system, which seems to be the case, I did not make the boot partition FAT32. This is what install guide says about that:

Quote:

Warning
If the boot partition is not using the FAT32 (vfat) file system, then the systems UEFI firmware will not be able to find the Linux kernel and boot the system!


When I run parted this is what I get:

Code:

Disk /dev/sda: 244198MiB
Sector size (logical/physical): 512B/512B
Partition Table: gpt
Disk Flags: pmbr_boot

Number  Start    End        Size       File system     Name    Flags
 1      1.00MiB  3.00MiB    2.00MiB                    grub    bios_grub
 2      3.00MiB  131MiB     128MiB     ext2            boot    boot, esp
 3      131MiB   643MiB     512MiB     linux-swap(v1)  swap
 4      643MiB   244197MiB  243554MiB  ext4            rootfs


@NeddySeagoon I tried booting after setting the boot flag - and was hoping this minor tweak would be the solution - but I restarted to same "Operation System...". For completeness:

fdisk
Code:

Device     Boot Start       End   Sectors   Size Id Type
/dev/sda1  *        1 500118191 500118191 238.5G ee GPT


gdisk
Code:

Number  Start (sector)    End (sector)  Size       Code  Name
   1            2048            6143   2.0 MiB     EF02  grub
   2            6148          268287   128.0 MiB   EF00  boot
   3          268288         1316863   512.0 MiB   8300  swap
   4         1316864       500116143   237.8 GiB   8300  rootfs


While it is not the worst thing in the world for me to redo much of the Gentoo installation - I probably have better things to do with the time. :^) So I'm still hoping to avoid doing that if possible. I have a couple thoughts:

  • If the problem is that my boot partition (2) needs to be vfat then perhaps it's possible to convert it without losing data?
  • Use my idea about always booting off my USB stick.

If I've left out any details, sorry about that...just let me know and I'll post them.

And thanks for the help! I much appreciate it.
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v_andal
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PostPosted: Thu May 07, 2015 2:27 pm    Post subject: Reply with quote

If you have EFI system, then you must have partition with FAT32 and code EF00 (EFI System). EFI shall use it for searching for bootable images. Default path for bootable image on 64-bit systems is EFI/Boot/bootx64.efi (relative to that partition). You can copy data from your partition 2 to some location, format it, and then copy your data back, but it really shouldn't contain anything but EFI/Boot/bootx64.efi

Some BIOSes allow disabling of EFI, in which case MBR should contain bootloader.
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m1ngsheng
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PostPosted: Thu May 07, 2015 4:12 pm    Post subject: Reply with quote

Thanks @v_andal! I've tried searching web to determine whether or not I have an EFI system - because it seemed like something my configuration had to be based off of.

I still don't know for sure. Any thoughts how to know for sure whether my system is EFI? My BIOS settings do not show any indicator/control of it.

Thanks again.
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NeddySeagoon
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PostPosted: Thu May 07, 2015 6:57 pm    Post subject: Reply with quote

m1ngsheng,

What motherboard or system do you have?
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NeddySeagoon

Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail.
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m1ngsheng
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PostPosted: Thu May 07, 2015 8:39 pm    Post subject: Reply with quote

This pretty much matches my system: http://wiki.gentoo.org/wiki/Dell_XPS_13_Ultrabook

I hope that helps. Thanks!
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m1ngsheng
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PostPosted: Fri May 08, 2015 12:16 pm    Post subject: Reply with quote

I created a USB stick, using fdisk, basically following the handbook but using vfat for boot partition. I copied my backed up boot files and, after config changes and grub install/make, was able to boot into my root partition.

So what seems to have worked for my system is using MBR. Go figure.

I'm either going to backup/reformat/restore, or if possible I'd like to change my GPT to MBR with some tool.

Thanks so much for all the help!
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