UEFI oddity.

[Chris Murphy]

On Mar 19, 2014, at 9:35 AM, Erik P. Olsen <epodata at gmail.com> wrote:

> I have recently built a fedora 20 system using UEFI. And by and large it seems to be OK. I took care to allocate enough space on disk to allow for another system. It's all done on a Lenovo L430 with a 500GB large harddisk. I intent to use it for testing purposes and the UEFI based system is my first try of this type of "BIOS".
> 
> I was very surprised to see the output from fdisk:
> 
> Disk /dev/sda: 465.8 GiB, 500107862016 bytes, 976773168 sectors
> Units: sectors of 1 * 512 = 512 bytes
> Sector size (logical/physical): 512 bytes / 512 bytes
> I/O size (minimum/optimal): 512 bytes / 512 bytes
> Disklabel type: gpt
> Disk identifier: 4547BE5B-EB5B-4756-8225-C346783B73AA
> 
> Device           Start          End   Size Type
> /dev/sda1         2048      1026047   500M Microsoft basic data
> /dev/sda2      1026048    205826047  97.7G Microsoft basic data
> /dev/sda3    205826048    222111743   7.8G Linux swap
> /dev/sda4    222111744    508831743 136.7G Microsoft basic data
> /dev/sda5    508831744    509241343   200M EFI System
> /dev/sda6    509241344    510265343   500M Microsoft basic data
> /dev/sda7    510265344    526551039   7.8G Linux swap
> /dev/sda8    526551040    631408639    50G Microsoft basic data
> /dev/sda9    631408640    976773119 164.7G Microsoft basic data
> 
> There doesn't seem to be much space left for yet another system :-(

Well you have two systems on here it looks like. Two /boot partitions, two swaps, and four other partitions that are conceivably root and home, times 2. So maybe mount sda2, sda4, sda8, sda9 and see if you can find an /etc/fstab. I bet you find two, and it'll tell you, along with blkid, how these two systems are assembled.




> 
> Doing a df -H yields:
> 
> Filesystem      Size  Used Avail Use% Mounted on
> /dev/sda8        53G  6.8G   44G  14% /
> devtmpfs        4.1G     0  4.1G   0% /dev
> tmpfs           4.1G   70k  4.1G   1% /dev/shm
> tmpfs           4.1G  1.2M  4.1G   1% /run
> tmpfs           4.1G     0  4.1G   0% /sys/fs/cgroup
> tmpfs           4.1G   41k  4.1G   1% /tmp
> /dev/sda9       174G  1.5G  164G   1% /home
> /dev/sda6       500M   99M  371M  21% /boot
> /dev/sda5       210M   10M  200M   5% /boot/efi
> 
> And here it looks like I have ample space for a second system.

You have a 2nd system. It's on /dev/sda[1234].

> 
> What should I believe and what does Microsoft do on my system?

You mean the "Microsoft basic data" partition type? Yeah, that. So with GPT partition scheme, the partition type isn't a 1 byte value anymore, it's 16 bytes. There are effectively unlimited partitiontypeGUIDs available, yet the parted project decided to use the existing Microsoft basic data partitiontypeGUID. I don't know why but it bends my brain trying to think of a good reason to have done that, when they did pick unique GUIDs for Linux swap, Linux (auto)RAID, and Linux LVM. But then used Microsoft basic data for "other" which includes rootfs, separate boot, var, LUKS, and home partitions. Madness.

Some years ago Rod Smith, creator of gdisk, started setting a unique GUID for Linux general purpose use. Parted doesn't have an upstream release with that patch yet. However Fedora rawhide does carry it and will start using that partitiontypeGUID starting with Fedora 21. Much later than it should be, but at least it's going to happen, finally.

And then recently there's an explosion of partitiontypeGUIDs, most of which aren't yet in parted, some of which are in gdisk. I'm not sure where fdisk is at with this as it just recently started supporting gpt partition scheme.
http://www.freedesktop.org/wiki/Specifications/DiscoverablePartitionsSpec/


Chris Murphy