4 ms·

So this means modern macs essentially have 4 copies of OS X installed? One regular, 2 recoveries, and whatever runs on their management controller(Bridge OS? Do

by meibo 6y ago

So this means modern macs essentially have 4 copies of OS X installed? One regular, 2 recoveries, and whatever runs on their management controller(Bridge OS? Does that still exist on M1 macs?) and the touch bar. Seems to work out fine for them if it creates resilience and makes code-sharing/interoperability easy.

choeger 6y ago
Maybe they had to make up for the Minix running on the Intel processors...
giuliomagnifico 6y ago
>have 4 copies of OS X Probably 2, the official boot and the recovery are macOS: the other 2 are iOS kernel for touchbar and controller. But I haven't digged into it.
- messe 6y ago
  > the other 2 are iOS kernel for touchbar and controller On Intel yes, as it's managed by the T2 chip which runs bridgeOS (which IIRC is based on watchOS rather than iOS, but it's XNU all the way down regardless). On M1 chips the controller functions have been integrated into the M1 chip, and I was under the impression that the touchbar was too; i.e. it's now controlled directly by macOS.
  - adolph 6y ago
    Within the M1 is a “Secure Enclave” for the stuff that was formerly in T1. Does that mean that there is an iOS running inside the macOS? https://support.apple.com/guide/security/secure-enclave-sec59b0b31ff/web https://support.apple.com/guide/security/secure-enclave-sec5...
    - SllX 6y ago
      No. From the document you cited: “ The Secure Enclave Processor runs an Apple-customized version of the L4 microkernel. It’s designed to operate efficiently at a lower clock speed that helps to protect it against clock and power attacks. The Secure Enclave Processor, starting with the A11 and S4, includes a memory-protected engine and encrypted memory with anti-replay capabilities, secure boot, a dedicated random number generator, and its own AES engine.” iOS still has an XNU kernel. L4 is a different beast entirely and being used for a different role here.
      - adolph 6y ago
        Thanks! It’s interesting to read about the history of L4, which Wikipedia claims developed out of dissatisfaction about XNU predecessor Mach’s performance. https://en.wikipedia.org/wiki/L4_microkernel_family https://en.wikipedia.org/wiki/L4_microkernel_family
        SllX 6y ago
        No problemo. :)
xenadu02 6y ago
M1 Macs do not have a T2 coprocessor like Intel Macs. The Touch Bar on M1 systems is run by macOS directly. macOS also handles talking to the Secure Enclave.

by meibo 6y ago

choeger 6y ago

Maybe they had to make up for the Minix running on the Intel processors...

giuliomagnifico 6y ago

>have 4 copies of OS X Probably 2, the official boot and the recovery are macOS: the other 2 are iOS kernel for touchbar and controller. But I haven't digged into it.

messe 6y ago
> the other 2 are iOS kernel for touchbar and controller On Intel yes, as it's managed by the T2 chip which runs bridgeOS (which IIRC is based on watchOS rather than iOS, but it's XNU all the way down regardless). On M1 chips the controller functions have been integrated into the M1 chip, and I was under the impression that the touchbar was too; i.e. it's now controlled directly by macOS.
- adolph 6y ago
  Within the M1 is a “Secure Enclave” for the stuff that was formerly in T1. Does that mean that there is an iOS running inside the macOS? https://support.apple.com/guide/security/secure-enclave-sec59b0b31ff/web https://support.apple.com/guide/security/secure-enclave-sec5...
  - SllX 6y ago
    No. From the document you cited: “ The Secure Enclave Processor runs an Apple-customized version of the L4 microkernel. It’s designed to operate efficiently at a lower clock speed that helps to protect it against clock and power attacks. The Secure Enclave Processor, starting with the A11 and S4, includes a memory-protected engine and encrypted memory with anti-replay capabilities, secure boot, a dedicated random number generator, and its own AES engine.” iOS still has an XNU kernel. L4 is a different beast entirely and being used for a different role here.
    - adolph 6y ago
      Thanks! It’s interesting to read about the history of L4, which Wikipedia claims developed out of dissatisfaction about XNU predecessor Mach’s performance. https://en.wikipedia.org/wiki/L4_microkernel_family https://en.wikipedia.org/wiki/L4_microkernel_family
      - SllX 6y ago
        No problemo. :)

xenadu02 6y ago

M1 Macs do not have a T2 coprocessor like Intel Macs. The Touch Bar on M1 systems is run by macOS directly. macOS also handles talking to the Secure Enclave.