Hello everyone, I've encountered a very strange and persistent logging issue with my DriverKit DEXT and would appreciate any insights from the community. [Problem Summary] My DriverKit DEXT, along with its companion Swift app, is functionally working perfectly. I can repeatedly call methods in the DEXT from the app (e.g., a Ping-Pong test and a StaticProcessInbandTask call) and receive the correct response every time. However, the os_log messages within my IOUserClient subclass are only successfully recorded for the very first set of interactions. After that, all subsequent logs are completely missing. What's even stranger is that all successfully recorded logs are attributed to the kernel: process, even for purely user-space methods like ExternalMethod. [Development Environment] macOS: 15.7.1 Xcode: 16.4 Hardware: MacBook Pro M1 DEXT Logging Macro (Log.h): #include <os/log.h> #define Log(fmt, ...) \ do { \ os_log(OS_LOG_DEFAULT, "[%{public}s] " fmt, __FUNCTION__, ##__VA_ARGS__); \ } while (0) [Steps to Reproduce & Observed Behavior] The DEXT is successfully loaded via the companion app. I click the "Ping-Pong" button, then the "Process InBand" button in the app. The app's UI log correctly shows that the request was sent and a successful response was received from the DEXT. I repeat step 2 multiple times. Each interaction works flawlessly from the app's perspective. I then use the log show command to export the logs from this period, for example: log show --last 5m | grep "com.accusys.Acxxx.driver" > dext_logs.txt Observed Result (Log Content): In the dext_logs.txt file, I can only see the logs from the very first Ping-Pong and the very first Process InBand call. All subsequent, successful operations leave no trace in the logs. kernel: (com.accusys.Acxxx.driver.dext) [ExternalMethod] // { --- kernel: (com.accusys.Acxxx.driver.dext) [ExternalMethod] // --- } kernel: (com.accusys.Acxxx.driver.dext) [StaticPingPong] // { --- kernel: (com.accusys.Acxxx.driver.dext) [StaticPingPong] // --- } kernel: (com.accusys.Acxxx.driver.dext) [ExternalMethod] // { --- kernel: (com.accusys.Acxxx.driver.dext) [ExternalMethod] // --- } kernel: (com.accusys.Acxxx.driver.dext) [StaticProcessInbandTask] // { --- kernel: (com.accusys.Acxxx.driver.dext) [StaticProcessInbandTask] // --- } <--- END OF FILE (No new logs appear after this point) ---> [Core Questions] Why are logs in IOUserClient subclass only recorded once? Given the DEXT is clearly still running and processing requests, why would os_log calls only succeed in writing to the system log database on the first interaction? Why are all logs attributed to the kernel? Why would logs from 100% user-space code like ExternalMethod and StaticPingPong be attributed to the kernel process? [Solutions Attempted That Did Not Work] I have verified with ps aux that the DEXT process (com.accusys.Acxxx.driver) is running continuously in the background and has not crashed. Attempted to force-restart the logging service with sudo killall logd, but the issue persists. Performed the most thorough reset possible using systemextensionsctl reset followed by a full reboot, then reinstalled the DEXT. The issue remains exactly the same. Thank you for any possible help or suggestions Best, Charles

We want to allocate a block of contiguous memory (≤1M) for audio ring DMA usage, but we haven't found any explicit method in the DriverKit documentation for allocating contiguous memory. I'm aware that IOBufferMemoryDescriptor::Create can be used in DriverKit to allocate memory and share it with user space. However, is the allocated memory physically contiguous? Can it guarantee that when I subsequently call PrepareForDMA in IODMACommand, there will be only one segment? Could you please help review this? Thank you!

We have an IOUserSCSIPeripheralDeviceType00 class DEXT supporting USB attached devices. With some high-capacity drives, the default setPowerState can exceed 20s to complete. This triggers a kernel panic, although this drive behavior is not unexpected. With a kernel extension implementing similar functionality we see no such problem as it appears from reading of Apple open source the timeout was 100s. What changes will allow setPowerState to complete without the kernel panic? kernel panic report excerpt attached. panic-full-2025-09-04-063127.0003.txt

We've developed a PCIDriverKit driver for the capture card on macOS and have identified an issue: CreateMemoryDescriptorFromClient can only read data from the user space to the driver, but cannot write data back to the user. typedef struct _MWCAP_EDID_DATA { uint64_t size; uint64_t uaddr; } MWCAP_EDID_DATA; // App size_t xxx::GetEdid(void *buff, size_t size) { MWCAP_EDID_DATA edid; edid.size = size; edid.uaddr = (uint64_t)buff; kr = IOConnectCallStructMethod( connect, kUserGetEdid, &edid, sizeof(MWCAP_EDID_DATA), NULL, NULL ); // kr is 0. But However, the data in the buffer remains unchanged; // it does not reflect the EDID copied from the DEXT. return size; } // Driver MWCAP_EDID_DATA *edid = (MWCAP_EDID_DATA *)input; IOMemoryDescriptor *user_buf_mem = NULL; IOAddressSegment segment; segment.address = edid->uaddr; segment.length = edid->size; // We have verified that the values in edid->uaddr and edid->size are consistent with what was set by the application. ret = CreateMemoryDescriptorFromClient(kIOMemoryDirectionOutIn, 1, &segment, &user_buf_mem); if (ret != kIOReturnSuccess) { os_log(OS_LOG_DEFAULT, "Failed to create memdesc with error: 0x%08x", ret); break; } IOMemoryMap* user_buf_map = nullptr; ret = user_buf_mem->CreateMapping(0, 0, 0, 0, 0, &user_buf_map); if (ret != kIOReturnSuccess) { os_log(OS_LOG_DEFAULT, "Failed to create mapping with error: 0x%08x", ret); OSSafeReleaseNULL(user_buf_mem); break; } // ... fill the user_buf_map with edid data ... // For example: // memcpy(user_buf_map->GetAddress(), source_edid_data, edid->size); // At this point we have also verified the data in user_buf_map->GetAddress(), which matches our expectations. OSSafeReleaseNULL(user_buf_map); OSSafeReleaseNULL(user_buf_mem); Please help take a look, thank you!

While developing our driver, we've noticed that the *.ips report that contains the stacktrace of the crash is not always generated. I'm wondering why this report may not get generated, or if there's anything specific to do to guarantee it gets generated.

Hi, Is it possible for a macOS (or iOS/ipadOS) app to communicate with a CCID-compliant reader using the CCID interface (i.e., directly sending the PC_TO_RDR_* messages) instead of using the CryptoTokenKit API? Apple's CCID driver (/System/Library/CryptoTokenKit/usbsmartcardreaderd.slotd) seems to support all the PC_TO_RDR and RDR_TO_PC messages: https://blog.apdu.fr/posts/2023/11/apple-own-ccid-driver-in-sonoma/#enable-my-ccid-driver The background for this question is that we develop smartcard products and we'd like to use the finer grained settings provided by the CCID specification for testing/demo purposes. Thank you.

Dear Apple engineers, We have developed a DriverKit (DEXT) driver for an HBA RAID controller. The RAID controller is connected to hosts through Thunderbolt (PCIe port of the Thunderbolt controller). We do plug/unplug tests to verify the developed driver. The test always fails in about 100 cycles with a MacOS crash (panic). The panic contains “LLC Bus error (Unavailable) from cpu0: FAR=0xa40100008 LLC_ERR_STS/ADR/INF=0x80/0x300480a40100008/0x1400000005 addr=0xa40100008 cmd=0x18(ACC_CIFL2C_CMD_RD_LD: request for load miss in E or S state)” At first we assumed that the issue is with hardware. But we did this test on different hosts (MacMini M3 and M4) with different units of our device. The error points to the same physical address FAR=0xa40100008 even if the hosts are different. The 2 full panic logs are attached (one for M4, another one for M3 host). Could you share your understanding of the crash and give any hints on how we can fix it? Please let us know if you need any additional data. Thank you M3 panic: https://drive.google.com/file/d/1GJXd3tTW6ajdrHpFsJxO_tWWYKYIgcMc/view?usp=share_link M4 panic: https://drive.google.com/file/d/1SU-3aBSdhLsyhhxsLknzw9wGvBQ9TbJC/view?usp=share_link

Hello, We have developed a hardware product that embeds an FTDI USB-serial converter, and an application on MacOS that communicates with this device. We would like to port our application to iPadOS. I can see that when I plug the device into the iPad, it is recognized as a serial port, based on its console logs. When I attempt to enumerate serial ports on iPadOS using IOKit, I can see matching IOSerialBSDClient services, but the properties are sandboxed, including the IOCalloutDevice property, for example: 0 error 16:36:10.922450-0700 kernel Sandbox: ***(662) deny(1) iokit-get-properties iokit-class:IOUserSerial property:IOTTYSuffix Is there an entitlement that can be applied that allows access to the serial port properties of an attached USB device? Or do I need to implement my own USBDriverKit driver for this device, as seems to be implied in these forum threads: https://developer.apple.com/forums/thread/795202 https://developer.apple.com/forums/thread/655527

Hello everyone, I am migrating a legacy KEXT to a DriverKit (DEXT) architecture. While the DEXT itself is working correctly, I am completely blocked by a code signing issue when trying to establish the UserClient connection from our SwiftUI management app. Project Goal & Status: Our DEXT (com.accusys.Acxxx.driver) activates successfully (systemextensionsctl list confirms [activated enabled]). The core functionality is working (diskutil list shows the corresponding disk device node). The Core Problem: The userclient-access Signing Error To allow the app to connect to the DEXT, the com.apple.developer.driverkit.userclient-access entitlement is required in the app's .entitlements file. However, as soon as this entitlement is added, the build fails. Both automatic and manual signing fail with the same error: `Provisioning profile ... doesn't match the entitlements file's value for the ... userclient-access entitlement.` This build failure prevents the generation of an .app bundle, making it impossible to inspect the final entitlements with codesign. What We've Confirmed: The necessary capabilities (like DriverKit Communicates with Drivers) are visible and enabled for our App ID on the developer portal. The issue persists on a clean system state and on the latest macOS Sequoia 15.7.1. Our Research and Hypothesis: We have reviewed the official documentation "Diagnosing issues with entitlements" (TN3125). According to the documentation, a "doesn't match" error implies a discrepancy between the entitlements file and the provisioning profile. Given that we have tried both automatic and manual profiles (after enabling the capability online), our hypothesis is that the provisioning profile generation process on Apple's backend is not correctly including the approved userclient-access entitlement into the profile file itself. The build fails because Xcode correctly detects this discrepancy. Our Questions: Did we misunderstand a step in the process, or is the issue not with the entitlement request at all? Alternatively, are there any other modifications we can make to successfully connect our App to the DEXT and trigger NewUserClient? Thank you for any guidance.

I have a USB-device with three interfaces: Vendor-Specific Bulk CDC Serial Control CDC Serial Data To configure the vendor specific bulk endpoints I need to send vendor specific control requests to endpoint 0. I'm using libusb for this task. As long as the interfaces for the CDC serial port are present I get an access error when trying to send vendor control requests. If I disable these CDC interfaces I can send vendor control request without any problems: Is this by design or ist there any possibility to send vendor control requests to the USB device while a CDC driver is active?

Dear Apple engineers and DriverKit developers, We have developed a DriverKit (DEXT) driver for an HBA RAID controller. The RAID controller is connected to hosts through Thunderbolt (PCIe port of the Thunderbolt controller). We use an IO script to verify the developed driver. The test fails after a few (10-12) hours of running with an error: “BUG IN CLIENT OF LIBDISPATCH: dispatch_sync called on queue already owned by current thread”. We inspected the stack trace of the crash report. This error happens in the interrupt handler. Thread 5 Crashed: 0 libdispatch.dylib 0x19671aa8c __DISPATCH_WAIT_FOR_QUEUE__ + 484 1 libdispatch.dylib 0x19671a5d0 _dispatch_sync_f_slow + 152 2 DriverKit 0x195d3fc1c IODispatchQueue::DispatchSync_f(void*, void (*)(void*)) + 296 3 DriverKit 0x195d40860 IOInterruptDispatchSourceThread(void*) + 380 4 libsystem_pthread.dylib 0x1968a3738 _pthread_start + 140 5 libsystem_pthread.dylib 0x1968ac6c8 thread_start + 8 On our side we created 5 DispatchQueue(s) for the interrupt processing and configured 5 interrupt handlers using ConfigureInterrupts(kIOInterruptTypePCIMessagedX, 1, 5). It gives 5 interrupts, as requested and it is not clear what is the reason for the issue. Our code samples are below uint32_t configureInterrupts(uint32_t requested, uint32_t required)  {      const kern_return_t ret = ioPCIdevice->ConfigureInterrupts(kIOInterruptTypePCIMessagedX, required, requested);      if (ret != kIOReturnSuccess)          return 0;      uint64_t interruptType = 0;      uint32_t interruptsCount = 0;      uint32_t interruptIndex = 0;        for ( ;; ++interruptIndex) {          if (IOInterruptDispatchSource::GetInterruptType(ioPCIdevice, interruptIndex, &interruptType) != kIOReturnSuccess)              break;          if ((interruptType & kIOInterruptTypePCIMessagedX) == 0)              continue;          ++interruptsCount;      }      return interruptsCount;  }  ..... // Create DQs     for(int i = 0; i < maxInterrupts; ++i) {          ret = IODispatchQueue::Create(INTERRUPT_DQ_NAME, 0, 0, &ivars->interruptQueue[i]);          if (kIOReturnSuccess != ret || nullptr == ivars->interruptQueue[i]) {              GH_PRINT_ERR("Interrupts queue %d creation failed with error %d", i, ret);              return false;          }      } ..... // Link DQ with interrupt   for(int index = 0; index < maxInterrupts; ++ index) {      kern_return_t ret = CreateActionHandleInterruptRequest(size, &ivars->interruptActions[index]);      if (kIOReturnSuccess != ret) {          GH_PRINT_ERR("Create action for interrupt handler %u failed.", index);          return ;      }      ret = IOInterruptDispatchSource::Create(ivars->PCI_io.dev, index, ivars->interruptQueue[index], &ivars->interruptSources[index]);      if (kIOReturnSuccess != ret || nullptr == ivars->interruptSources[index]) {          GH_PRINT_ERR("Creating interrupt source %u failed for interrupt index %u.", index, index);          return ;      }      ret = ivars->interruptSources[index]->SetHandler(ivars->interruptActions[index]);      if (kIOReturnSuccess != ret) {          GH_PRINT_ERR("Setting the handler for interrupt source %u failed.", index);          return ;      }      ivars->contexts[index] = ivars->interruptActions[index]->GetReference();      }  ..... // definition for interrupt handler void    HandleInterruptRequest ( OSAction *action, uint64_t count, uint64_t time) TYPE (IOInterruptDispatchSource::InterruptOccurred);  Do you have any clue how we can fix this error? Or directions and ways for investigation? Please let us know if you need more details.

Hi, We are using the AX88772C as a USB->Ethernet bridge in a product we are developing. Due to the chip not following the NCM protocol, it is not supported by the default networking drivers on the iPhone. Initially, we intended on using DriverKit to develop a userspace driver for this device. However, we have been informed DriverKit is only available on iPad OS, not iOS. As such is the case, we have found two possible alternatives. First being IOkit, and the second being External Accessory Session (EASession). What are the limitations of each of these options? We need the ability to send and receive USB packets to Control and Bulk endpoints. Is this possible with either of the options defined above? Would either of these options require the device to be MFi certified? We have read that some APIs within IOkit require the apple device to be jailbroken. Is there a list of features that can be used without a jailbroken device? Documentation on these 2 options is limited, so any official documentation would be great. Thanks!

1) The circumstances: iPADOS~>18, USB still-imaging-gadget, 1-3 gadgets might connect simultaneously via USB-hub, proprietary DExt, UserClient App in developers' iPADs or in TestFlight. = 1 variation A) UserClientApp has attribute [Background modes][Enable external communications]. = 1 variation B) "active USB-hub" vs "passive". = 1 variation C) "ConsoleApp logs iPAD" vs "ConsoleApp is not started". = 1 the term "zombie" below assume issue: == after plug-in ConsoleApp logs "IOUsbUserInterface::init", "::start"; == UserClient never receives respective callback from IOServiceAddMatchingNotification == further IOKit APIs "teardown", "restart" and "re-enumeration of connected gadgets" doesn't reveal the zombie (while it sees another simultaneous gadget); == unplug of the gadget logs "IOUsbUserInterface::stop". =2) The situation when UserClient is in foreground: ~ everything is fine. Note in MAC OS everything (same DExt and UserClient-code) works fine in background and in foreground. =3) The situation when UserClient is in background (beneath ~"Files" or "Safari"): =3A) "1A=true" phys plugin causes zombie in ~1/20 cases (satisfactory) =3B) "1A=false" phys plugin causes zombie in ~1/4 cases (non-satisfactory) =3C) "1 variation B" and "1 variation C" reduce zombies by ~>30%. =3D) ConsoleApp logs with filter "IOAccessory" (~about USB-energy) always look similar by my eyes. =4) From Apple-store: "The app declares support for external-accessory in the UIBackgroundModes"..."The external accessory background mode is intended for apps that communicate with hardware accessories through the External Accessory framework."..."Additionally, the app must be authorized by MFi," =5) My wish/ask: =5 option A) A clue to resolve the "zombie-plugin-issue in background" in a technical manner. = E.g. find a straightforward solution that ~elevates UserClient's "privileges" in background like [Enable external communication]... E.g. what ConsoleApp-logs to add/watch to reveal my potential bugs in DExt or in UserClient? =5 option B) A way to pursue Apple-store to accept (without MFI) an UserClientApp with [Enable external communication].

The device I am trying to develop a firmware updater for is an NVMe drive with a USB4 interface. It can connect in USB4 mode (tunneled NVMe), in USB 3 mode or in USB 2 mode. In USB 2 and USB 3 mode, the device descriptor shows one interface with two alternates. Alternate 0 uses the bulk-only protocol, with one IN and one OUT pipe. Alternate 1 uses the UAS protocol, with two IN and two OUT pipes. I use identical code in my driver to send custom CDBs. I can see using IORegistryExplorer that in USB 2 mode, macOS chooses alternate 0, the bulk-only protocol. My custom CDBs and their accompanying data pay loads are put on the bus, more or less as expected. In USB 3 mode, macOS chooses alternate 1, the UAS protocol. My custom CDB is put on the bus, but no payload data is transferred. Is this expected behavior? If so, is there a way to force the OS to choose alternate 0 even when on USB 3, perhaps with another dext? I'll file a bug about this when Feedback Assistant lets me.

We have a management application which manages security enable and disable for an external PCIe based storage device using Kernel Extension(SCSI Architecture Model Family for External USB Mass Storage devices which deals with IOSCSIBlockCommandsDevice, IOSCSIPeripheralDeviceType00 and IOBlockStorageService) Now the issue we are facing is when we try to unlock the device using security code (already being set) , we will relink the device using VU command (RelinkBridge). Even-though both the commands are successful , the device is not getting relinked due to which we are not able to use the device for storage. If someone have faced similar issue or any pointer on how to resolve this issue , it would be helpful. Thanks in advance.

Hi everyone, We are experiencing an issue with SMS messages sent from our banking app (iOS) to our customers. The SMS are being delivered by the carrier, but on iOS devices some of them appear to be filtered or blocked, and users don’t see them in the Messages app. This seems to be related to new SMS filtering rules on iOS (possibly affecting financial institutions and transactional SMS). • Has anyone faced a similar situation? • Are there specific Apple guidelines or best practices for SMS sender IDs / content to avoid being filtered? • Is there any official documentation from Apple regarding these new SMS filtering mechanisms? Any guidance or experiences would be greatly appreciated. Thanks in advance!

Hi, We were planning on using DriverKit to develop a USB Driver on IOS for iPhone. Within the DriverKit website, it say 'IOS16.0+' which lead us to believe it was compatible with iPhones running IOS16.0+. However, it appears DriverKit is only available for iPads running iPadOS, and computers running macOS. Are there any alternatives that would allow us to create a device specific USB driver for an iPhone running IOS?

I've made a dext and a user client that overrides IOUserSCSIPeripheralDeviceType00, with the object of writing device firmware to the driver. I can gain and relinquish exclusive access to the device, I can call UserReportMediumBlockSize and get back a sensible answer (512). I can build command parameters with the INQUIRY macro from IOUserSCSIPeripheralDeviceHelper.h and send that command successfully using UserSendCB, and I receive sensible-looking Inquiry data from the device. However, what I really want to do is send a WriteBuffer command (opcode 0x3B), and that doesn't work. I have yet to put a bus analyzer on it, but I don't think the command goes out on the bus - there's no valid sense data, and the error returned is 0xe00002bc, or kIOReturnError, which isn't helpful. This is the code I have which doesn't work. kern_return_t driver::writeChunk(const char * buf, size_t atOffset, size_t length, bool lastOne) { DebugMsg("writeChunk %p at %ld for %ld", buf, atOffset, length); SCSIType00OutParameters outParameters; SCSIType00InParameters response; memset(&outParameters, 0, sizeof(outParameters)); memset(&response, 0, sizeof(response)); SetCommandCDB(&outParameters.fCommandDescriptorBlock, 0x3B, // byte 0, opcode WriteBuffer command lastOne ? 0x0E : 0x0F, // byte 1 mode: E=save deferred, F = download and defer save 0, // byte 2 bufferID (atOffset >> 16), // byte 3 (atOffset >> 8), // byte 4 atOffset, // byte 5 (length >> 16), // byte 6 (length >> 8), // byte 7 length, // byte 8 0, // control, byte 9 0, 0, 0, 0, 0, 0); // bytes 10..15 outParameters.fLogicalUnitNumber = 0; outParameters.fBufferDirection = kIOMemoryDirectionOut; outParameters.fDataTransferDirection = kSCSIDataTransfer_FromInitiatorToTarget; outParameters.fTimeoutDuration = 1000; // milliseconds outParameters.fRequestedByteCountOfTransfer = length; outParameters.fDataBufferAddr = reinterpret_cast<uint64_t>(buf); uint8_t senseBuffer[255] = {0}; outParameters.fSenseBufferAddr = reinterpret_cast<uint64_t>(senseBuffer); outParameters.fSenseLengthRequested = sizeof(senseBuffer); kern_return_t retVal = UserSendCDB(outParameters, &response); return retVal; }

Hi Apple, We are working on a general USB device management solution on macOS for enterprise security. Our goal is to enforce policy-based restrictions on USB devices, such as: For USB storage devices: block mount, read, or write access. For other peripherals (e.g., USB headsets or microphones, raspberry pi, etc): block usage entirely. We know in past, kernel extension would be the way to go, but as kext has been deprecated. And DriverKit is the new advertised framework. At first, DriverKit looked like the right direction. However, after reviewing the documentation more closely, we noticed that using DriverKit for USB requires specific entitlements: DriverKit USB Transport – VendorID DriverKit USB Transport – VendorID and ProductID This raises a challenge: if our solution is meant to cover all types of USB devices, we would theoretically need entitlements for every VendorID/ProductID in existence. My questions are: Is DriverKit actually the right framework for this kind of general-purpose USB device control? If not, what framework or mechanism should we be looking at for enforcing these kinds of policies? We also developed an Endpoint Security product, but so far we haven’t found a relevant Endpoint Security event type that would allow us to achieve this. Any guidance on the correct technical approach would be much appreciated. Thanks in advance for your help.

Hello everyone, I'm developing a CarPlay app and am trying to test it with the dock on the right side of the screen, as is standard for right-hand drive vehicles like those in Japan. Currently, the CarPlay Simulator always displays the dock on the left, and I can't find an option to change its position. This is important for ensuring a proper user experience for my target market. Has anyone figured out how to configure the simulator for RHD layouts? Any guidance on how to move the dock to the right would be greatly appreciated. Thanks in advance for your help!