What Happens During Startup?
12 days ago
- #Mac startup
- #FileVault
- #Apple silicon
- Apple silicon Mac startup sequence includes Boot ROM, Low-Level Bootloader (LLB) and iBoot (Stage 2), kernel, and userspace.
- Boot ROM hands over to LLB and iBoot, which do not write to the Unified log but leave cryptic breadcrumbs.
- Kernel boot starts with 'kprintf initialized' and includes wallclock adjustments, synchronizing the system clock.
- During the kernel phase, all CPU cores are started, and launchd is loaded before Data volume access.
- With FileVault enabled, macOS cannot access the Data volume until the user enters their password.
- The login window appears 10-15 seconds after boot, and Data volume unlocking is logged with specific entries.
- After Data volume unlock, log entries increase significantly, with userspace boot and access to user files.
- Before Data volume unlock, log entries are around 1,000 per second; after, they average 5,000 per second.