I have a custom USB Audio Class 2 (UAC2) compatible device. When I connect this custom device to a MacBook with a configuration of up to 10 channels (16-bit), everything seems to work fine. However, when I increase the channel count to 12, the MacBook does not recognize the 12 channels. It only shows the channel count as 0. TN2274 is the only source where I found some information about Apple's Audio Class Drivers, but it doesn't mention any limitations regarding channel counts. Could you let me know the current limitations of the Audio Class Drivers on the latest macOS versions? What configuration should I use to get 12 channels working? P.S. I also found that a 12-channel, 8-bit configuration is detected by the MacBook, bit I want it to work with 16bits. For more detail please check FB17098863

When I develop the system extension tool, I need to subscribe to the remote thread creation event. When the remote thread injection is triggered, I want to get the id, module name and starting function name of the remote thread. How can I get this information from es_event_remote_thread_create_t? If I can't get this information from es_event_remote_thread_create_t, is there any other way to get it?

Hello Everyone, I'm encountering an issue while setting up a timer event in DriverKit and would appreciate any guidance. Here's my current implementation: void DRV_MAIN_CLASS_NAME::SetupEventTimer() { // 1. Create dispatch queue kern_return_t ret = IODispatchQueue::Create("TimerQueue", 0, 0, &ivars->dispatchQueue); if (ret != kIOReturnSuccess) { LogErr("Failed to create dispatch queue: 0x%x", ret); return; } // 2. Create timer source ret = IOTimerDispatchSource::Create(ivars->dispatchQueue, &ivars->dispatchSource); if (ret != kIOReturnSuccess) { LogErr("Failed to create timer: 0x%x", ret); OSSafeReleaseNULL(ivars->dispatchQueue); return; } /*! * @brief Create an instance of OSAction. * @discussion Methods to allocate an OSAction instance are generated for each method defined in a class with * a TYPE attribute, so there should not be any need to directly call OSAction::Create(). * @param target OSObject to receive the callback. This object will be retained until the OSAction is * canceled or freed. * @param targetmsgid Generated message ID for the target method. * @param msgid Generated message ID for the method invoked by the receiver of the OSAction * to generate the callback. * @param referenceSize Size of additional state structure available to the creator of the OSAction * with GetReference. * @param action Created OSAction with +1 retain count to be released by the caller. * @return kIOReturnSuccess on success. See IOReturn.h for error codes. */ // 3: Create an OSAction for the TimerOccurred method // THIS IS WHERE I NEED HELP OSAction* timerAction = nullptr; ret = OSAction::Create(this, 0, 0, 0, &timerAction); if (ret != kIOReturnSuccess) { LogErr("Failed to create OSAction: 0x%x", ret); goto cleanup; } // 4. Set handler ret = ivars->dispatchSource->SetHandler(timerAction); if (ret != kIOReturnSuccess) { LogErr("Failed to set handler: 0x%x", ret); goto cleanup; } // 5. Schedule timer (1 second) uint64_t deadline = mach_absolute_time() + NSEC_PER_SEC; ivars->dispatchSource->WakeAtTime(0, deadline, 0); cleanup: if (ret != kIOReturnSuccess) { OSSafeReleaseNULL(timerAction); OSSafeReleaseNULL(ivars->dispatchSource); OSSafeReleaseNULL(ivars->dispatchQueue); } } Problem: The code runs but the OSAction callback binding seems incorrect (Step 3). According to the OSAction documentation, I need to use the TYPE macro to properly bind the callback method. But I try to use TYPE(DRV_MAIN_CLASS_NAME::TimerOccurred) kern_return_t TimerOccurred() LOCALONLY; TYPE(TimerOccurred) kern_return_t TimerOccurred() LOCALONLY; kern_return_t TimerOccurred() TYPE(DRV_MAIN_CLASS_NAME::TimerOccurred) LOCALONLY; All results in Out-of-line definition of 'TimerOccurred' does not match any declaration in 'DRV_MAIN_CLASS_NAME' Questions: What is the correct way to declare a timer callback method using TYPE? How to get the values targetmsgid & msgid generated by Xcode? Any help would be greatly appreciated! Best Regards, Charles

I’m experiencing a persistent issue with the new USB-C lossless audio feature on AirPods Max (firmware 7E101). I’m using original Apple USB-C to USB-C cable and have tested this setup across multiple Apple devices, including: • iPhone (running iOS 18.5 beta) • iPad Pro with USB-C • MacBook Pro (15.5 Beta) ❗️Problem: Despite Apple’s announcement that AirPods Max now support wired lossless audio over USB-C, I’m unable to get any audio output via USB-C on any device. • On iPhone: I disabled Bluetooth, connected via USB-C — no sound. • On MacBook: The device is shown as “AirPods Max USB Audio” in System Information > USB, but it does not appear in Sound settings or Audio MIDI Setup as an available output. • On iPad Pro: Same behavior — no audio output. Other details: • I performed a factory reset of the headphones, but the LED flashes red instead of the expected amber → white sequence. (Apple’s documentation does not mention red flash behavior during reset — might indicate an error state.) • The issue is not isolated to the iOS 18.5 beta — since the same behavior occurs on macOS and iPadOS. What works: • Bluetooth audio still works fine. • The cable and USB-C ports function with other audio devices. ⸻ Summary: It looks like: • USB audio is being detected on a hardware level (at least on Mac), • but software support for output (especially on macOS/iPadOS) is either not implemented, disabled, or bugged — possibly connected to iOS 18.5 beta or broader OS-level limitations.

Hi, trying to upgrade from macOS Sequoia 15.3.2 to 15.4 gives this error. Now I can not boot from internal drive of M1 Air 2020, because it restores 15.4, that does not boot. I can only boot from external USB SSD that has macOS 15.3.2. How I can install back 15.3.2 or alternatively newer macOS to internal drive? I only have one Mac, this M1 Air 2020. I have AppleAppleCare+ to 9/18/25. Remaining of error is attached here: Can't ignore lock validation @t8020dart.c:535 panic(cpu 2 caller 0x0): t8020dart 0xfffffdf053908000 (dart-dispext0): Can't ignore lock validation @t8020dart.c:535 Debugger message: panic Memory ID: 0x6 OS release type: Not set yet OS version: Not set yet Kernel version: Darwin Kernel Version 24.4.0: Wed Mar 19 21:12:54 PDT 2025; root:xnu-11417.101.15~1/RELEASE_ARM64_T8103 Fileset Kernelcache UUID: 2BBA525B95E0E6B962ECC44FC093AB57 Kernel UUID: 4E6CBD31-CD1E-3939-8A63-211A206AFA66 Boot session UUID: 3A34167D-2534-402F-9679-2CAD45F67CDA iBoot version: iBoot-11881.101.1 iBoot Stage 2 version: iBoot-11881.101.1 secure boot?: YES

Hello Everyone, I encountered an issue with PCI memory access in DriverKit. In my case, BAR0 is not available, but BAR1 is ready for use. Here’s the log output: !!! ERROR : Failed to get BAR0 info (error: 0xe00002f0). !!! BAR1 - MemoryIndex: 0x00000000, Size: 0x00040000, Type: 0 Issue Description When I initially wrote to BAR0 using memoryIndex = 0, it worked successfully: AME_Address_Write_32(pAMEData, pAMEData->memoryIndex, AME_HOST_INT_MASK_REGISTER, 0x0F); However, I mistakenly forgot to update memoryIndex to 1 for BAR1. Surprisingly, the write operation still succeeded. When I fixed memoryIndex = 1 for BAR1, the write operation no longer had any effect. There was no error, but the expected behavior did not occur. Relevant API (From IOPCIDevice.iig) /*! /*! * @brief Writes a 32-bit value to the PCI device's aperture at a given memory index. * @discussion This method writes a 32-bit register on the device and returns its value. * @param memoryIndex An index into the array of ranges assigned to the device. * @param offset An offset into the device's memory specified by the index. * @param data A 32-bit value to be written in host byte order. */ void MemoryWrite32(uint8_t memoryIndex, uint64_t offset, uint32_t data) LOCALONLY; Log Output: Writes to BAR0 (memoryIndex = 0) AME_Address_Write_32() called memoryIndex: 0, offset: 0x34, data: 0xf Wrote data 0xF to offset 52 AME_Address_Write_32() called memoryIndex: 0, offset: 0xa0, data: 0x1 Wrote data 0x1 to offset 160 AME_Address_Write_32() called memoryIndex: 0, offset: 0x20, data: 0xffffffff Wrote data 0xFFFFFFFF to offset 32 Writes to BAR1 (memoryIndex = 1) – No Response AME_Address_Write_32() called memoryIndex: 1, offset: 0x34, data: 0xf No confirmation log, no visible effect. Questions What should memoryIndex be set to for BAR1? The log shows "BAR1 - MemoryIndex: 0x00000000", but should I be using 1 instead? How can I verify if a write operation to BAR1 is successful? Is there a way to check if the memory region is actually writable? Should I use MemoryRead32() to confirm the written value? Any guidance would be greatly appreciated! Best Regards, Charles

We have a macOS application which interacts with our USB and PCI devices to perform SCSI and NVME commands on them. We use IOUSBHost, IOUSBLib and IOKitLib for USB interface and have created a custom driver to interact with PCI devices. Is there a way we can implement a similar functionality for iOS as well if we connect the cards and readers using OTG?

When plugging in my matched USB device I see the logs below. It seems the kernelmanagerd process is sandboxed and can't write out the reason my Dext failed to load. Is there somewhere else I can look for this info? default 11:03:22.175152-0700 kernelmanagerd Received kext load notification: me.keithg.MyUserUSBInterfaceDriver default 11:03:22.177637-0700 kernel 1 duplicate report for Sandbox: icdd(2124) allow file-read-data /Library/Image Capture/Devices error 11:03:22.177681-0700 kernel Sandbox: kernelmanagerd(545) deny(1) file-write-create /private/var/folders/zz/zyxvpxvq6csfxvn_n0000000000000/T/com.apple.kernelmanagerd/TemporaryItems com.apple.libcoreservices error 11:03:22.177711-0700 kernelmanagerd mkdir: path=/var/folders/zz/zyxvpxvq6csfxvn_n0000000000000/T/com.apple.kernelmanagerd/TemporaryItems/ mode= -rwx------: [1: Operation not permitted] error 11:03:22.179361-0700 kernel Sandbox: kernelmanagerd(545) deny(1) file-write-create /private/var/db/loadedkextmt.plist.sb-5a00fc77-LNttZF com.apple.libcoreservices error 11:03:22.177755-0700 kernelmanagerd _dirhelper_relative_internal: error for path <private>: [1: Operation not permitted] com.apple.accessories default 11:03:22.177674-0700 WindowServer Sending analytics event... (eventName: com.apple.ioport.transport.USB.published) error 11:03:22.179913-0700 kernelmanagerd Failed to write extension load report plist.