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I'm trying to understand what exactly is made possible by Media Device Discovery Extensions, what responsibility the containing app has, and what exactly is made available to other apps or the system, if anything.
I haven't been able to find any meaningful high level documentation, and WWDC 2022 session 10096 only mentions these new extensions in passing. The most comprehensive body of information I found is the example project:
https://developer.apple.com/documentation/devicediscoveryextension/discovering_a_third-party_media-streaming_device?changes=latest_beta&language=objc
However, I don't think it's working the way it should out of the box:
I've got the Client target app built and running on an iPad Pro running iPadOS 16 Beta 2
I've got the MacServer target running on a Mac Mini with macOS 13 Ventura Beta 2
I've got the Server target running on an iPhone with iOS 15.5. (Non-beta)
If I tap the AirPlay icon on the Client's video player, I can see the two servers, but selecting one just causes a spinner to show up next to its name. This keeps going for a while, eventually the spinner goes away again, but the device selection tick stays next to 'iPad'. The text "Select route" also doesn't change, which I think it's supposed to, judging by the code.
I've tried a variety of combinations of settings on the servers - bluetooth only, bonjour only, different protocols, etc., but I'm always getting the same behaviour.
Has anyone had any success in getting the example to work, and how? Is there any high level documentation available that I've missed?
Can someone explain what exactly we can build with this in more detail than "implementations of custom A/V streaming protocols?" The WWDC session video talks about 3rd party SDKs, so do these extensions have to be embedded in every app that would be streaming the video, implying that it's not useful for mirroring?
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I'm trying to use the SIMD group reduction/prefix functions in a series of reasonably complex compute kernels in a Mac app. I need to allocate some threadgroup memory for coordinating between SIMD groups in the same thread group. This array should therefore should have a capacity depending on [[simdgroups_per_threadgroup]], but that's not a compile time value, so it can't be used as an array dimension.
Now, according to various WWDC session videos (e.g. WWDC2022 "Scale compute workloads acroos Apple GPUs), threadExecutionWidth on the pipeline object should return the SIMD group size, with which I could then allocate an appropriate amount of memory using setThreadgroupMemoryLength:atIndex: on the compute encoder.
This works consistently on some hardware (e.g. Apple M1, threadExecutionWidth always seems to report 32) but I'm hitting configurations where threadExecutionWidth does not match apparent SIMD group size, causing runtime errors due to out of bounds access. (e.g. on Intel UHD Graphics 630, threadExecutionWidth = 16 for some complex kernels, although SIMD group size seems to be 32)
Will the SIMD group size always be the same for all kernels on a device, so should I trust threadExecutionWidth only for the most trivial of kernels? Or should I submit a trivial kernel to the GPU which returns [[threads_per_simdgroup]]?
I suspect the problem might occur in kernels where Metal offers an "odd" (non-pow2) maximum thread group sizes due to exhaustion of some resource (registers?), although in the case I'm encountering, the maximum threadgroup size is reported as 896, which is an integer multiple of 32, so it's not as if it's using the greatest common denominator between max threadgroup size and SIMD group size for threadExecutionWidth.
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I'm trying to get to grips with the new System Extensions mechanism, as it looks like I'll need to port some of the kexts I help maintain to this new tech, at least once it reaches sufficient feature parity. I can't really start filing ERs until I've given it a try though. So I've been putting together a demo app with a system extension but have now run into a roadblock.Basically, my activation request is failing with OSSystemExtensionErrorExtensionNotFound and I don't understand why or how to fix it.I created a new Cocoa App Xcode project, then added an "App Proxy" type network extension target to the project. Xcode automatically set it up to be embedded in the .app bundle at Contents/Library/SystemExtensions/ - I ultimately need to use the Endpoint Security API, but there's no Xcode integration for that yet, it seems.I've got SIP disabled (so it shouldn't be an issue of missing entitlements in the signing cert), and the extension and app are both signed with a Mac Developer cert. I've added com.apple.developer.system-extension.install to the App's .entitlements.In the App, I have: OSSystemExtensionRequest* request =
[OSSystemExtensionRequest activationRequestForExtension:@"my.rdns.prefix.EndpointSecurityDemo"
queue:dispatch_get_main_queue()];
request.delegate = self;
[[OSSystemExtensionManager sharedManager] submitRequest:request];I build the extension & app, then copy the app to /Applications to avoid OSSystemExtensionErrorUnsupportedParentBundleLocation.When run, the above code results in the request:didFailWithError: delegate method being called with an error code of OSSystemExtensionErrorExtensionNotFound.In Console.app, I can't see anything other than what my app logs, plus sysextd's "request contains no authorizationref" and "attempting to realize extension with identifier my.rdns.prefix.EndpointSecurityDemo". As there's no API for specifying an auth ref, I assume the first message isn't something I can do anything about.I've verified that the bundle identifier in the code matches the one in the system extension's plist once it's in the built app bundle. And the extension is definitely located at Contents/Library/SystemExtensions within the built .app.I'm at a loss as to why sysextd(?) can't find my extension. Is there any example code I can compare against? Any documentation I might have missed? The DriverKit WWDC session video is a nice conceptual intro but is very light on practicalities. Beyond that, I'm just using the OSSystemExtensions (and EndpointSecurity) headerdocs.Bonus question: In the headerdocs for OSSystemExtensionRequestDelegate I noticed a mention of "If the local system has System Extension developer mode enabled, this callback will always fire when an existing extension is found, regardless of version identifiers." What is this mode and how do I enable it?Update: For the heck of it, I tried with a DriverKit driver target (.dext). sysextd does find this one, and request:didFinishWithResult: returns 0 (OSSystemExtensionRequestCompleted) and I get a kext-like approval dialog. (I'm not convinced the dext actually ran after I approved it though, I certainly can't find the "Hello World" it's supposed to os_log anywhere, and it doesn't appear in ioreg.)
I'm trying to port an existing kext-based driver to DriverKit. My client has requested the relevant signing entitlements, but they haven't come through yet. Fortunately, the documentation says that we can develop and test DriverKit drivers without these entitlements if we disable SIP on the target machine. Right?Quoting https://developer.apple.com/documentation/driverkit/requesting_entitlements_for_driverkit_development?language=objc> Note> While waiting for Apple to grant your entitlement requests, you can continue to develop and test your drivers on your local systems. For information about how to disable the necessary security checks, see Debugging and Testing System Extensions."That referenced page, https://developer.apple.com/documentation/driverkit/debugging_and_testing_system_extensions?language=objc then goes on to say I need to disable SIP on the target system, along with a command for disabling the /Applications/ directory requirement.Well, I can't get it working. I've set up a Cocoa app, and embedded a DriverKit target within it. I'm signing the app using a Mac Developer certificate and an explicitly-created provisioning profile which has the system extension capability and which matches the app's bundle ID. I've wired up a button in the app to set up and submit a OSSystemExtensionRequest and implemented the delegate methods.Configuring the entitlements and signing of the .dext bundle is where I'm having trouble:If I don't set the com.apple.developer.driverkit entitlement, I can sign, build, and embed the dext, but submitting the system extension activation request fails with error code 9: "Invalid extension configuration in Info.plist and/or entitlements" (OSSystemExtensionErrorValidationFailed)If I do set the com.apple.developer.driverkit entitlement, I cannot find any combination of settings with which Xcode will even allow me to kick off the build (names have been anonymised):error: Automatic signing is unable to resolve an issue with the "DriverTarget" target's entitlements. Automatic signing can't add the com.apple.developer.driverkit entitlement to your provisioning profile. Switch to manual signing and resolve the issue by downloading a matching provisioning profile from the developer website. Alternatively, to continue using automatic signing, remove this entitlement from your entitlements file and its associated functionality from your code. (in target 'DriverTarget' from project 'DriverProject')
error: Provisioning profile "Mac Team Provisioning Profile: *" doesn't include the com.apple.developer.driverkit entitlement. (in target 'DriverTarget' from project 'DriverProject')Both outcomes make logical sense:The system extension mechanism needs to know what kind of extension this is in order to install/activate it, and that appears to be done via the entitlements embedded in the code signature.You can't sign a binary with an entitlement for which your signing identity hasn't been whitelisted.The conclusion would therefore be that you can't build and test a DriverKit driver without explicitly being given permission by Apple. However:That appears to contradict the documentation.It doesn't make much logical sense why DriverKit is more restricted than kext development. Anyone curious about writing kexts can just turn off SIP and go wild, but only the chosen ones are allowed to tinker with DriverKit, the API that Apple is trying to push on everyone.So, have I missed something? What should I be doing to get this working?Incidentally, eskimo1's suggestion of setting the boot-arg here https://forums.developer.apple.com/thread/125048#394539 does not appear to make any difference, which makes sense as it's not actually amfid which is causing the failure.Full system log (### replacing non-public identifiers) for the relevant time frame:2020-04-16 12:19:20.992008+0200 0x1ef9 Default 0x3930 680 0 USB Display Device: installDriverButtonPushed: Submitted extension activation request
2020-04-16 12:19:20.994555+0200 0x1b65 Activity 0x3035 621 0 sysextd: (Security) SecTrustEvaluateIfNecessary
2020-04-16 12:19:20.995952+0200 0x1ded Default 0x3035 192 0 trustd: [com.apple.securityd:SecError] OCSPResponse: single response has extension(s).
2020-04-16 12:19:21.001309+0200 0x1b65 Default 0x3930 621 0 sysextd: attempting to realize extension with identifier ###
2020-04-16 12:19:21.002978+0200 0x1b65 Activity 0x3036 621 0 sysextd: (Security) SecTrustEvaluateIfNecessary
2020-04-16 12:19:21.004210+0200 0x1ded Default 0x3036 192 0 trustd: [com.apple.securityd:SecError] OCSPResponse: single response has extension(s).
2020-04-16 12:19:21.007341+0200 0x1b65 Default 0x3930 621 0 sysextd: Realizing target path:
2020-04-16 12:19:21.008133+0200 0x1b65 Default 0x3930 621 0 sysextd: Bundle class: UncachedBundle
2020-04-16 12:19:21.009911+0200 0x1b65 Activity 0x3037 621 0 sysextd: (Security) SecTrustEvaluateIfNecessary
2020-04-16 12:19:21.011170+0200 0x1ded Default 0x3037 192 0 trustd: [com.apple.securityd:SecError] OCSPResponse: single response has extension(s).
2020-04-16 12:19:21.013814+0200 0x1b65 Default 0x3930 621 0 sysextd: System extension does not appear to belong to any extension categories
2020-04-16 12:19:21.014108+0200 0x1ef9 Default 0x3930 680 0 USB Display Device: request:didFailWithError: Error Domain=OSSystemExtensionErrorDomain Code=9 "Invalid extension configuration in Info.plist and/or entitlements" UserInfo={NSLocalizedDescription=Invalid extension configuration in Info.plist and/or entitlements}
2020-04-16 12:19:21.014235+0200 0x1ef9 Default 0x3930 680 0 USB Display Device: Error code: 9
pmdj.