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At the point the hardware shipped, it was impossible to boot non-Apple operating systems on M1 systems. Post-release updates added this, but Apple had not publi

by mjg59 6y ago

At the point the hardware shipped, it was impossible to boot non-Apple operating systems on M1 systems. Post-release updates added this, but Apple had not publicly committed to doing so before that.

saagarjha 6y ago
Apple committed to this during WWDC, when they mentioned that they would have an option to dial the boot security back.
- mjg59 6y ago
  WWDC included discussion of "Reduced security" mode, which allows downgrading to old signed versions of MacOS, but I don't remember any disclosure of plans to permit arbitrary operating systems at that point - do you have a pointer? Edit: The transcript at https://developer.apple.com/videos/play/wwdc2020/10686/ https://developer.apple.com/videos/play/wwdc2020/10686/ discusses reduced security, but doesn't say anything about booting arbitrary code.
  - saagarjha 6y ago
    You found the right talk, but it’s actually only waved at and not explicitly discussed so it’s not in the transcript. At about 19 minutes the engineer mentions that a csrutil will be able to do more things and on the slide disabling secure boot is one of them. (This actually got moved into bputil, but the intent was there at least.)
    - mjg59 6y ago
      That indicates that csrutil would be able to do /something/ with secure boot policy, but I really don't interpret that as a commitment to being able to boot arbitrary operating systems - if we were still unable to do so today, I don't think you'd be able to put up a strong argument that Apple had broken a commitment.
      - saagarjha 6y ago
        The only thing I can plausibly interpret that as is “we’ll let you turn off secure boot” (I mean, what else can you do?). I agree that Apple never committed to anything beyond that (and I am pleasantly surprised as to how much effort and documentation went into what they have currently given) but I think it is a reasonable interpretation from the slides that getting some sort of OS loaded that isn’t Apple’s is something they had advertised.

by mjg59 6y ago

At the point the hardware shipped, it was impossible to boot non-Apple operating systems on M1 systems. Post-release updates added this, but Apple had not publicly committed to doing so before that.

saagarjha 6y ago

Apple committed to this during WWDC, when they mentioned that they would have an option to dial the boot security back.

mjg59 6y ago
WWDC included discussion of "Reduced security" mode, which allows downgrading to old signed versions of MacOS, but I don't remember any disclosure of plans to permit arbitrary operating systems at that point - do you have a pointer? Edit: The transcript at https://developer.apple.com/videos/play/wwdc2020/10686/ https://developer.apple.com/videos/play/wwdc2020/10686/ discusses reduced security, but doesn't say anything about booting arbitrary code.
- saagarjha 6y ago
  You found the right talk, but it’s actually only waved at and not explicitly discussed so it’s not in the transcript. At about 19 minutes the engineer mentions that a csrutil will be able to do more things and on the slide disabling secure boot is one of them. (This actually got moved into bputil, but the intent was there at least.)
  - mjg59 6y ago
    That indicates that csrutil would be able to do /something/ with secure boot policy, but I really don't interpret that as a commitment to being able to boot arbitrary operating systems - if we were still unable to do so today, I don't think you'd be able to put up a strong argument that Apple had broken a commitment.
    - saagarjha 6y ago
      The only thing I can plausibly interpret that as is “we’ll let you turn off secure boot” (I mean, what else can you do?). I agree that Apple never committed to anything beyond that (and I am pleasantly surprised as to how much effort and documentation went into what they have currently given) but I think it is a reasonable interpretation from the slides that getting some sort of OS loaded that isn’t Apple’s is something they had advertised.