Dual boot between El Cap and Sierra

Discussion in 'macOS Sierra (10.12)' started by Autistic Behaviour, Jun 14, 2016.

  1. Autistic Behaviour macrumors member

    Autistic Behaviour

    Joined:
    Sep 9, 2015
    Location:
    montreal
    #1
    I've asked this question already, and googled extensively without clear answers.
    My situation: Replaced optical drive with SSD and original HD with another SSD in mbp 13 mid 2012. El cap on my main drive, and, going to test Sierra on my 2nd.

    If, theres a efi bootrom update with Sierra, could it negatively affect how my El cap partition works?
    Or, are efi bootrom updates meant to be totally backwards compatible with older OS's?

    Thanks
     
  2. Weaselboy Moderator

    Weaselboy

    Staff Member

    Joined:
    Jan 23, 2005
    Location:
    California
    #2
    No guarantees I suppose, but in previous betas like El Capitan these EFI updates did not cause any issues with the older OS X versions.

    I would be surprised if Apple intentionally did anything to break older OS X versions, since you still need to be able to do Internet recovery which gets you the OS that came from the factory.
     
  3. Autistic Behaviour thread starter macrumors member

    Autistic Behaviour

    Joined:
    Sep 9, 2015
    Location:
    montreal
    #3
    Yeah, thats basically what Im thinking....Just irritating that I can't seem to find exact documentation on that particular subject ;)
    --- Post Merged, Jun 14, 2016 ---
    On the other hand, I do recall a few cases where people downgraded efi 1.7 to 1.6, because of problems with negotiated link speeds affected on installed ssd's, so....yeah, never know, I guess....;)
     

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