Q: Can't boot from Ubuntu partition after upgrading to Yosemite

A extensive report already written is in the Ubuntu stacks as

Dual boot Linux and Yosemite

Basically you need to follow http://www.rodsbooks.com/refind/yosemite.html

wherein it explains that Yosemite is using a new LVM bootup from within the Recovery Partitions 10.10.

This messes up REFIT/REFIND tools  which have previously installed Partition 1.S

See my current Table below , wherein << are my comments

Current GPT partition table:

#      Start LBA      End LBA  Type

1             40       409639  EFI System (FAT)    << old preferred site for REFIT/REFIND tools

2         409640    154061023  Mac OS X HFS+ << main Mac partition

3      154061024    155330559  Mac OS X Boot  << Recovery 10.10 , installed by Yosemite update, used to start MAC boot.  BUT is not shown by Disk Utility, to prevent its naive deletion which would kill the MAC boot.

4      155330560    156598271  Mac OS X HFS+ << old Recovery 10.9, simply retained

5      157869786    228772129  Unknown << My Ubuntu partition

6      228772130    236765969  Linux Swap << which was shortened by 200 MB to make room for 7)

7      236765970    236974814  Mac OS X HFS+ << installation site of REFIND.  Though 4) could have been used, there is a possibility that Apple might have future plans for this small 4) partition.  

With 7) created (see detail below),  my REFIND install command under MAC, within Downloads/refind-bin-0.8.3/ was:

sudo ./install.sh  --alldrivers --ownhfs  /dev/disk0s7

There was still required the edit if refind.conf.sample specified in Yosemite.html, which I named refind.conf.edit1

This was copied with:

sudo cp refind.conf.edit1  /Volumes/macefi/System/Library/CoreServices/refind.conf

macefi  is my name for the MAC  /dev/disk0s7 mount point, equivalent to /dev/sda7 under Linux

CAREFULLY do read Yosemite.html,  as the instructions here are too terse by themselves!!!!

There are 2 routes to  boot Ubuntu, and then creat 7) with GPARTED

a) If you can access the GRUB shell under an old REFIT/REFIND installation, partitions will be shown by:

grub> ls

Presence of a Linux file system can be confirmed by a command like:

grub> ls (hd0,gpt5)/

Output of

grub > ls (hd0,gpt5)/boot/grub/

should include a grub.cfg file.  Then you can boot as usual with

grub > configfile  (hd0,gpt5)/boot/grub/grub.cfg

After boot up, start GPARTED

b) Alternatively boot with the Ubuntu install disk, and choose the Demo option

Open a text console, and get admin proviledge with:

$ sudo su

# gparted

Using GPARTED, unmount if necessary  any terminal SWAP partition, such as my 6) above

Then shrink the SWAP partition end by a trivial 200 MB,

Create a HFS+ partition in like my 7) for a coming REFIND installation

Note, that a file /etc/fstab contains a SWAP partition specification, which should be edited for automated SWAP start.

# sudo blkid  /dev/sda7

will report the SWAP space specs LONG  uuid code.  This can be copied into memory by dragging the mouse over the uuid

Then SHIFT-CONTROL-C  will copy it into memory.   Start an edit with:

$ sudo nano /etc/fstab

delete the old swap uuid, and paste in the replacement with

SHIFT-CONTROl-V

and swap should mount upon reboot, or with:

$ sudo swapon -a

Check with:

$ free

which should report none-zero swap space.