4 ms·

Anyone know why you can’t use the first usb-c port on a Mac laptop to make the bootable os?

plussed_reader 3y ago
What if it's through a USB c adapter to a usbA thumbstick?
Tsiklon 3y ago
The ports mentioned expose the serial interface that can be used to restore/revive the machine in DFU mode https://support.apple.com/en-us/108900 https://support.apple.com/en-us/108900 That said, no idea why they can’t be used in this case
- joecool1029 3y ago
  > That said, no idea why they can’t be used in this case My intuitive guess here is how the ports are connected to the T2 security chip. One port is as you said a console port that allows access to perform commands to flash/recover/re-provision the T2 chip. Same as an OOB serial port on networking equip. The rest of the ports the T2 chip has read/write access to devices connected to it. Since this is an OS drive, I'm guessing it needs to be encrypted and the T2 chip handles this function.
  - amelius 3y ago
    That doesn't make it technically impossible to implement booting from that port.
    - p_l 3y ago
      The firmware is based on iPhone boot process from my understanding, and simply does not have space in ROM to implement boot from external storage. The rest of the code necessary to boot from external sources is located on main flash
      - amelius 3y ago
        Yes, but the decision to use this firmware was made by Apple. This is like saying my software did not work because it was based on an incompatible version of some library. Maybe so, but that is a bad excuse. Implementing systems is hard, and like the rest of us, Apple should not get away with bad excuses. And this is even more true because they control more of the stack.
        pjerem 3y ago
        OTOH, the current implementation works and is sufficient so Apple could easily decide that it’s not worth modifying firmware that already works to solve an inexistant issue.
        amelius 3y ago
        That's how you end up with a UX that works only for programmers (see e.g. Linux in the 90s).
        pjerem 3y ago
        We are talking about booting from USB. On a Mac M2. That’s literally the most power user feature of a MacBook. The 3 users of this feature on this planet are already happy that it’s even possible at all. The only thing Apple could do is to document this clearly like adding a text in the boot drive selector.
    - PeterisP 3y ago
      Sure, but it also doesn't make it necessary or useful to implement booting from that port - booting from a port IMHO is not a feature that Apple wants to offer to its target audience at all, so it's sufficient if some repair technician can do that according to a manual which says which port to use in which scenario.
- nottorp 3y ago
  > Mac laptop computer: Use any USB-C port except the leftmost USB-C port when facing the ports on the left side of the Mac. Also on my mbpro at least the mentioned port is the one closest to the magsafe connector and may have funny electrical connections to it, perhaps.

What if it's through a USB c adapter to a usbA thumbstick?

The ports mentioned expose the serial interface that can be used to restore/revive the machine in DFU mode https://support.apple.com/en-us/108900 https://support.apple.com/en-us/108900 That said, no idea why they can’t be used in this case

joecool1029 3y ago
> That said, no idea why they can’t be used in this case My intuitive guess here is how the ports are connected to the T2 security chip. One port is as you said a console port that allows access to perform commands to flash/recover/re-provision the T2 chip. Same as an OOB serial port on networking equip. The rest of the ports the T2 chip has read/write access to devices connected to it. Since this is an OS drive, I'm guessing it needs to be encrypted and the T2 chip handles this function.
- amelius 3y ago
  That doesn't make it technically impossible to implement booting from that port.
  - p_l 3y ago
    The firmware is based on iPhone boot process from my understanding, and simply does not have space in ROM to implement boot from external storage. The rest of the code necessary to boot from external sources is located on main flash
    - amelius 3y ago
      Yes, but the decision to use this firmware was made by Apple. This is like saying my software did not work because it was based on an incompatible version of some library. Maybe so, but that is a bad excuse. Implementing systems is hard, and like the rest of us, Apple should not get away with bad excuses. And this is even more true because they control more of the stack.
      - pjerem 3y ago
        OTOH, the current implementation works and is sufficient so Apple could easily decide that it’s not worth modifying firmware that already works to solve an inexistant issue.
        amelius 3y ago
        That's how you end up with a UX that works only for programmers (see e.g. Linux in the 90s).
        pjerem 3y ago
        We are talking about booting from USB. On a Mac M2. That’s literally the most power user feature of a MacBook. The 3 users of this feature on this planet are already happy that it’s even possible at all. The only thing Apple could do is to document this clearly like adding a text in the boot drive selector.
  - PeterisP 3y ago
    Sure, but it also doesn't make it necessary or useful to implement booting from that port - booting from a port IMHO is not a feature that Apple wants to offer to its target audience at all, so it's sufficient if some repair technician can do that according to a manual which says which port to use in which scenario.
nottorp 3y ago
> Mac laptop computer: Use any USB-C port except the leftmost USB-C port when facing the ports on the left side of the Mac. Also on my mbpro at least the mentioned port is the one closest to the magsafe connector and may have funny electrical connections to it, perhaps.