What is EFI boot?

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Level 1

31 points

What is EFI boot?

I had Yosemite on my MacBook Pro. I used Diskmaker X to create a bootable flash drive. Yesterday I did a clean install of El Capitan on my MBP. When I held down the "option" key, I saw "Macintosh HD" & the flash drive. I had minor problems installing El Capitan on my MBP but I figured them out & installed it.

This morning I tried to do a clean install of El Capitan on my Mac mini. It has Yosemite on it. I was able to cancel the installer & get to the Yosemite Desktop without screwing anything up. I started the disk utilities & the flash drive installer was listed. When I held down the "option" key, I saw "Macintosh HD", "Recovery" & "EFI boot". Why didn't I see the flash drive icon? What is EFI boot? I googled it & found out that it has something to do with Time Machine backups, but I don't have an external drive that I use to make Time Machine backups. What's going on? How do I get the flash drive icon to show up instead of EFI boot?

Mac mini, OS X Yosemite (10.10.3)

Posted on Nov 5, 2015 5:22 AM

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Answer 1

macnerd48 Author

Level 1

31 points

Nov 5, 2015 6:00 AM in response to macnerd48

I read about "bless --info" so I did it & this is what came up:

finderinfo[0]: 49 => Blessed System Folder is /System/Library/CoreServices

finderinfo[1]: 3751013 => Blessed System File is /System/Library/CoreServices/boot.efi

finderinfo[2]: 0 => Open-folder linked list empty

finderinfo[3]: 0 => No alternate OS blessed file/folder

finderinfo[4]: 0 => Unused field unset

finderinfo[5]: 49 => OS X blessed folder is /System/Library/CoreServices

64-bit VSDB volume id: 0x6500D7AE3A72109E

I don't understand why I was able to do a clean install of El Capitan on my MBP, but not on my mini. I didn't have the "EFI boot" problem when I did a clean install of Yosemite on my MBP & mini. Only the keyboard, mouse & Superdrive are plugged into the back of the mini. Should I unplug the Superdrive? Is it "confusing" OS X?

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Answer 2

macnerd48 Author

Level 1

31 points

Nov 5, 2015 7:47 AM in response to macnerd48

I just checked my laptop. I did a clean install of El Capitan on 11/3. The date on the boot.efi file is 11/3.

I checked my mini & the date for the boot.efi file is 5/24/2015. I didn't do a clean install of Yosemite on 5/24. I installed it last year. I don't use Time Machine.

What is going on??? How do I get the flash drive to show up when I do a clean install of El Capitan on my mini?

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Answer 3

lllaass

Level 10

210,423 points

Nov 5, 2015 9:23 AM in response to macnerd48

A Mac startup disk includes three items:

- The actual startup did. Default name is Macintosh HD

- EFI

- Recovery partition.

Sometimes an OSX update will update the EFi or Recovery and thus that will get a new date.

If you now insert the bootable Yosemite install in the MacBook and boot with the Option key is the Yosemite install listed?

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Answer 4

macnerd48 Author

Level 1

31 points

Nov 5, 2015 9:52 AM in response to lllaass

Tuesday, when I did a clean install of El Capitan on my laptop, the flash drive icon showed up NOT EFI Boot. This morning when I tried to install El Capitan on my mini, using the same flash drive, there was a white circle with a multicolored "X" in the option list NOT the flash drive icon. When I look at the info in Finder on the mini, I see "OS X 10.11.1 installer". I don't understand why the same flash drive has 2 names - "EFI Boot " & OS X Installer". I also don't understand why the flash drive icon shows up in the option list on the laptop & it's labelled "OS X Installer", but a white circle with a multicolored "X" shows up in the option list on the mini & it's labelled "EFI Boot". This morning I was scared that I'd screw something up, so I aborted the install on the mini. In Disk Utilities, I saw "OS X Installer". When I click on "Info" in Disk Utilities, I see Disk 1, Partition 2. I used Diskmaker X. Does the bootable flash drive have 2 partitions? So, you can see my confusion & fear. How do I get the flash drive icon to show up in the option list on the mini just like on the laptop?

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Answer 5

macnerd48 Author

Level 1

31 points

Nov 8, 2015 6:33 AM in response to macnerd48

I did it!

I successfully installed El Capitan on my mini.

The install steps on the mini weren't the same as on the laptop.

It is confusing to an Apple newbie when the mini shows "EFI Boot" & the laptop shows "OS X Installer". It sure would be great if Apple would be consistent & have the exact same install process on all of their computers.

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