In the development Linux 6.11 kernel, EFI changes have been incorporated. On the EFI side, notable this cycle is the removal of support for EFI pseudo-memory mapping, as well as a workaround to provide dual-GPU support for some older x86-based Apple MacBook Pros by pretending to boot Apple macOS instead of Linux.
EFI pseudo-memory mapping support is being removed from the Linux kernel because it is not currently used and results in confidential computing (CoCo) virtual machines, unaccepted memory handling, and other complications. This feature has been primarily used for EFI debugging in the past.
Another change worth mentioning is a SMBIOS "tweak" that instructs the x86 MacBook Pro's firmware to enable both integrated and discrete GPUs. The Linux kernel already supports MMIOGMUX on T2-based Apple Macs for use with discrete GPUs. However, preventing firmware from disabling the integrated GPU requires special handling. In particular, the firmware needs to disable the iGPU and only enable the dGPU when booting Apple macOS.
Therefore, in Linux 6.11, for a few known Apple MacBook Pro models, the EFISMBIOS code reports that "Mac OS X 10.9" is booting from the operating system vendor "Apple Inc." to prevent the iGPU from being disabled. The MacBookPro models currently set to disable iGPU are: MacBookPro11,3, MacBookPro11,5, MacBookPro13,3, MacBookPro14,3, MacBookPro15,1, MacBookPro15,3, MacBookPro16,1 and MacBookPro16,4.
This follows a GRUB patch in 2013 where certain MacBook models would identify themselves as MacOSX on boot, in response to the firmware's different configuration of the hardware, if not reported as "MacOSX" on boot. So if you're using one of these older x86 MacBook Pro models and Linux 6.11 is recognized as "Mac OS
For more details on all EFI feature updates this cycle, see yesterday's EFI merge into Linux 6.11 Git.