> On 11 Feb 2025, at 1:39 AM, Lukas Wunner <lukas@xxxxxxxxx> wrote: > > On Wed, Jan 01, 2025 at 11:39:13AM +0000, Aditya Garg wrote: >> We have had issues with other people unable to use their eGPU if their >> Mac doesn't have the apple set os quirk. We probably could do dual VGA >> checks suggested by Lukas, but will it work with GPU hotplug? > > About hotplug: There is a tiny time window when the EFI stub runs > during which an eGPU may be hotplugged and incorrectly not be > detected. I.e. the quirk is not applied. I don't think this can > be fixed. > > If an eGPU is hotplugged while EFI boot services are still running, > Apple's EFI Thunderbolt driver will set up a tunnel to the device > and it will then be visible to the kernel's efi stub. E.g. if you > hold down the Option key during boot and attach an eGPU, then > select the operating system to boot, the eGPU should correctly be > seen by the efi stub and the quirk is applied. > > However hotplugging an eGPU at exactly the moment when the efi stub > runs results in a race between the efi stub doing all the initialization > and exiting boot services on the one hand, and the EFI Thunderbolt > driver bringing up the eGPU on the other hand. > > But IMO this is "good enough". Something is better than nothing. I'll test your patch, and imo restricting it to Apple devices should be a good idea. > > Thanks, > > Lukas
