Richard Speed reports via The Register: Asahi Linux, a project aimed at porting Linux to Apple Silicon Macs, reported a combination of bugs in Apple’s macOS that could leave users with hardware in a difficult-to-recover state. The issues revolve around how recent versions of macOS handle refresh rates, and MacBook Pro models with ProMotion displays (the 14- and 16-inch versions) are affected. According to the Asahi team, the bugs lurk in the upgrade and boot process and, when combined, can create a condition where a machine always boots to a black screen and update recovery from the Device Firmware (DFU) is required.
Asahi Linux technicians looked into the problem, first suspecting that it had something to do with installing Asahi Linux on a Mac, then upgrading to macOS Sonoma, or installing ‘Asahi Linux after a Sonoma upgrade. However, the problem does not seem to be related to the project. The team said: “As far as we know, ALL users who upgraded to Sonoma in the normal way have an outdated or even broken system recovery, and especially MacBook Pro 14 owners ” and 16″ are vulnerable at the end. with a completely unbootable system.” While this may sound alarming, the team worked to assure users that data was not at risk and that only certain versions of macOS were affected: Sonoma 14.0+ and Ventura 13.6+.
The first bug is related to macOS Sonoma using the previously installed version as system recovery, which can cause issues when an older RecoveryOS is running on newer firmware. The second occurs if a display is set to a refresh rate other than ProMotion. According to the Asahi Linux team, the system will no longer be able to boot on older macOS or Asahi Linux installations. “This includes recovery mode when these systems are set as the default boot operating system, as well as recovering the system at least until the next subsequent operating system upgrade.” The team noted: “Even users with only 13.6 installed in single boot are affected by this issue (no Asahi Linux required).
“We do not understand how Apple managed to release an operating system update that, during a normal upgrade, prevents machines from booting if their display refresh rate is not that par This appears to have been a major quality assurance oversight on Apple’s part.”