Kevin's Guide to DEXT Signing The question of "How do I sign a DEXT" comes up a lot, so this post is my attempt to describe both what the issue are and the best current solutions are. So... The Problems: When DEXTs were originally introduced, the recommended development signing process required disabling SIP and local signing. There is a newer, much simpler process that's built on Xcode's integrated code-signing support; however, that newer process has not yet been integrated into the documentation library. In addition, while the older flow still works, many of the details it describes are no longer correct due to changes to Xcode and the developer portal. DriverKit's use of individually customized entitlements is different than the other entitlements on our platform, and Xcode's support for it is somewhat incomplete and buggy. The situation has improved considerably over time, particularly from Xcode 15 and Xcode 16, but there are still issues that are not fully resolved. To address #1, we introduced "development" entitlement variants of all DriverKit entitlements. These entitlement variants are ONLY available in development-signed builds, but they're available on all paid developer accounts without any special approval. They also allow a DEXT to match against any hardware, greatly simplifying working with development or prototype hardware which may not match the configuration of a final product. Unfortunately, this also means that DEXT developers will always have at least two entitlement variants (the public development variant and the "private" approved entitlement), which is what then causes the problem I mentioned in #2. The Automatic Solution: If you're using Xcode 16 or above, then Xcode's Automatic code sign support will work all DEXT Families, with the exception of distribution signing the PCI and USB Families. For completeness, here is how that Automatic flow should work: Change the code signing configuration to "Automatic". Add the capability using Xcode. If you've been approved for one of these entitlements, the one oddity you'll see is that adding your approved capability will add both the approved AND the development variant, while deleting either will delete both. This is a visual side effect of #2 above; however, aside from the exception described below, it can be ignored. Similarly, you can sign distribution builds by creating a build archive and then exporting the build using the standard Xcode flow. __ Kevin Elliott DTS Engineer, CoreOS/Hardware

Note: This document is specifically focused on what happens after a DEXT has passed its initial code-signing checks. Code-signing issues are dealt with in other posts. Preliminary Guidance: Using and understanding DriverKit basically requires understanding IOKit, something which isn't entirely clear in our documentation. The good news here is that IOKit actually does have fairly good "foundational" documentation in the documentation archive. Here are a few of the documents I'd take a look at: IOKit Fundamentals IOKit Device Driver Design Guidelines Accessing Hardware From Applications Special mention to QA1075: "Making sense of IOKit error codes",, which I happened to notice today and which documents the IOReturn error format (which is a bit weird on first review). Those documents do not cover the full DEXT loading process, but they are the foundation of how all of this actually works. Understanding the IOKitPersonalities Dictionary The first thing to understand here is that the "IOKitPersonalities" is called that because it is in fact a fully valid "IOKitPersonalities" dictionary. That is, what the system actually uses that dictionary "for" is: Perform a standard IOKit match and load cycle in the kernel. The final driver in the kernel then uses the DEXT-specific data to launch and run your DEXT process outside the kernel. So, working through the critical keys in that dictionary: "IOProviderClass"-> This is the in-kernel class that your in-kernel driver loads "on top" of. The IOKit documentation and naming convention uses the term "Nub", but the naming convention is not consistent enough that it applies to all cases. "IOClass"-> This is the in-kernel class that your driver loads on top of. This is where things can become a bit confused, as some families work by: Routing all activity through the provider reference so that the DEXT-specific class does not matter (PCIDriverKit). Having the DEXT subclass a specific subclass which corresponds to a specific kernel driver (SCSIPeripheralsDriverKit). This distinction is described in the documentation, but it's easy to overlook if you don't understand what's going on. However, compare PCIDriverKit: "When the system loads your custom PCI driver, it passes an IOPCIDevice object as the provider to your driver. Use that object to read and write the configuration and memory of your PCI hardware." Versus SCSIPeripheralsDriverKit: Develop your driver by subclassing IOUserSCSIPeripheralDeviceType00 or IOUserSCSIPeripheralDeviceType05, depending on whether your device works with SCSI Block Commands (SBC) or SCSI Multimedia Commands (SMC), respectively. In your subclass, override all methods the framework declares as pure virtual. The reason these differences exist actually comes from the relationship and interactions between the DEXT families. Case in point, PCIDriverKit doesn't require a specific subclass because it wants SCSIControllerDriverKit DEXTs to be able to directly load "above" it. Note that the common mistake many developers make is leaving "IOUserService" in place when they should have specified a family-specific subclass (case 2 above). This is an undocumented implementation detail, but if there is a mismatch between your DEXT driver ("IOUserSCSIPeripheralDeviceType00") and your kernel driver ("IOUserService"), you end up trying to call unimplemented kernel methods. When a method is "missing" like that, the codegen system ends up handling that by returning kIOReturnUnsupported. One special case here is the "IOUserResources" provider. This class is the DEXT equivalent of "IOResources" in the kernel. In both cases, these classes exist as an attachment point for objects which don't otherwise have a provider. It's specifically used by the sample "Communicating between a DriverKit extension and a client app" to allow that sample to load on all hardware but is not something the vast majority of DEXT will use. Following on from that point, most DEXT should NOT include "IOMatchCategory". Quoting IOKit fundamentals: "Important: Any driver that declares IOResources as the value of its IOProviderClass key must also include in its personality the IOMatchCategory key and a private match category value. This prevents the driver from matching exclusively on the IOResources nub and thereby preventing other drivers from matching on it. It also prevents the driver from having to compete with all other drivers that need to match on IOResources. The value of the IOMatchCategory property should be identical to the value of the driver's IOClass property, which is the driver’s class name in reverse-DNS notation with underbars instead of dots, such as com_MyCompany_driver_MyDriver." The critical point here is that including IOMatchCategory does this: "This prevents the driver from matching exclusively on the IOResources nub and thereby preventing other drivers from matching on it." The problem here is that this is actually the exceptional case. For a typical DEXT, including IOMatchCategory means that a system driver will load "beside" their DEXT, then open the provider blocking DEXT access and breaking the DEXT. DEXT Launching The key point here is that the entire process above is the standard IOKit loading process used by all KEXT. Once that process finishes, what actually happens next is the DEXT-specific part of this process: IOUserServerName-> This key is the bundle ID of your DEXT, which the system uses to find your DEXT target. IOUserClass-> This is the name of the class the system instantiates after launching your DEXT. Note that this directly mimics how IOKit loading works. Keep in mind that the second, DEXT-specific, half of this process is the first point your actual code becomes relevant. Any issue before that point will ONLY be visible through kernel logging or possibly the IORegistry. __ Kevin Elliott DTS Engineer, CoreOS/Hardware

I'm developing a DriverKit USB driver for iPadOS that needs to communicate with a vendor-class USB device (bInterfaceClass = 0xFF) as I need to communicate with a USB device using a custom protocol over IOUSBHostPipe for bulk transfers. Current Configuration: Info.plist: IOProviderClass = IOUSBHostDevice Device: bDeviceClass = 0, bInterfaceClass = 0xFF (vendor-specific) What Works: Driver matches and loads successfully Start_Impl() executes device->Open() succeeds device->SetConfiguration() succeeds The Problem: uintptr_t iterRef = 0; kern_return_t ret = device->CreateInterfaceIterator(&iterRef); Result: ret = kIOReturnSuccess (0x0), but iterRef = 0 (empty iterator) What I've Tried: Matching IOUSBHostInterface directly - Driver is loaded, but extension never executed Current approach (IOUSBHostDevice) - Driver extension loads and starts, but CreateInterfaceIterator returns empty Question: Does iPadOS allow third-party DriverKit extensions to access vendor-class (0xFF) USB devices? That is, iPadOS, is there a way for a third-party DriverKit extension to access IOUSBHostInterface objects for vendor-class (0xFF) USB devices?

This is my first driver and I have had the devil of a time trying to find any information to help me with this. I beg help with this, since I cannot find any tutorials that will get me over this problem. I am attempting to write a bridging driver for an older UPS that only communicates via RPC-over-USB rather than the HID Power Device class the OS requires. I have written the basic framework for the driver (details below) and am calling OSSystemExtensionRequest.submitRequest with a request object created by OSSystemExtensionRequest.activationRequest, but the didFailWithError callback is called with OSSystemExtensionErrorDomain of a value of 9, which appears to be a general failure to activate the driver. I can find no other information on how to address this issue, but I presume the issue is one of entitlements in either the entitlements file or Info.plist. I will have more code-based details below. For testing context, I am testing this on a 2021 iMac (M1) running Sequoia 15.7, and this iMac is on MDM, specifically Jamf. I have disabled SIP and set systemextensionsctl developer on, per the instructions here, and I have compiled and am attempting to debug the app using xcode 26.2. The driver itself targets DriverKit 25, as 26 does not appear to be available in xcode despite hints on google that it's out. For the software, I have a two-target structure in my xcode project, the main Manager app, which is a swift-ui app that both handles installation/activation of the driver and (if that finally manages to work) handles communication from the driver via its UserClient, and the driver which compiles as a dext. Both apps compile and use automated signing attached to our Apple Development team. I won't delve into the Manager app much, as it runs even though activation fails, except to include its entitlements file in case it proves relevant <dict> <key>com.apple.developer.driverkit.communicates-with-drivers</key> <true/> <key>com.apple.developer.system-extension.install</key> <true/> <key>com.apple.security.app-sandbox</key> <true/> <key>com.apple.security.files.user-selected.read-only</key> <true/> </dict> and the relevant activation code: func request(_ request: OSSystemExtensionRequest, didFailWithError error: any Error) { // handling the error, which is always code value 9 } func activateDriver() { let request = OSSystemExtensionRequest.activationRequest(forExtensionWithIdentifier: "com.mycompany.driver.bundle.identifier", queue: .main) request.delegate = self OSSystemExtensionManager.shared.submitRequest(request) //... } And finally the Manager app has the following capabilities requested for its matching identifier in our Apple Developer Account: DriverKit Communicates with Drivers System Extension On the Driver side, I have two major pieces, the main driver class MyDriver, and UserClient class, StatusUserClient. MyDriver derives from IDriverKit/IOService.iig but (in case this is somehow important) does not have the same name as the project/target name MyBatteryDriver. StatusUserClient derives from DriverKit/IOUserClient.iig. I have os_log(OS_LOG_DEFAULT, "trace messages") code in every method of both classes, including the initializers and Start implementations, and the log entries never seem to show up in Console, so I presume that means the OS never tried to load the driver. Unless I'm looking in the wrong place? Because I don't think the driver code is the current issue, I won't go into it unless it becomes necessary. As I mentioned above, I think this is a code signing / entitlements issue, but I don't know how to resolve it. In our Apple Developer account, the Driver's matching identifier has the following capabilities requested: DriverKit (development) DriverKit Allow Any UserClient (development) DriverKit Family HID Device (development) -- NOTE: this is planned for future use, but not yet implemented by my driver code. Could that be part of the problem? DriverKit Transport HID (development) DriverKit USB Transport (development) DriverKit USB Transport - VendorID -- submitted, no response from Apple yet HID Virtual Device -- submitted, no response from Apple. yet. This is vestigial from an early plan to build the bridge via shared memory funneling to a virtual HID device. I think I've found a way to do it with one Service, but... not sure yet. Still, that's a problem for tomorrow. Apparently I've gone over the 7000 character maximum so I will add my entitlements and info.plist contents in a reply.

1. 环境描述 (Environment) OS: macOS 26.2 Hardware: Apple Silicon (M1/M2/M3) DriverKit SDK: DriverKit 19.0 / 20.0 Arch: Universal (x86_64, arm64, arm64e) SIP Status: Enabled (Works perfectly when Disabled) 2. 问题现象 (Problem Description) 在开启 SIP 的环境下，USB 驱动扩展（Dext）能安装，但插入设备时无法连接设备（驱动的Start方法未被调用）。 驱动状态： MacBook-Pro ~ % systemextensionsctl list 1 extension(s) --- com.apple.system_extension.driver_extension (Go to 'System Settings > General > Login Items & Extensions > Driver Extensions' to modify these system extension(s)) enabled active teamID bundleID (version) name [state] * * JK9U78YRLU com.ronganchina.usbapp.MyUserUSBInterfaceDriver (1.3/4) com.ronganchina.usbapp.MyUserUSBInterfaceDriver [activated enabled] 关键日志证据 (Key Logs) KernelManagerd: Error Domain=NSPOSIXErrorDomain Code=8 "Exec format error" Syspolicyd: failed to fetch ... /_CodeSignature/CodeRequirements-1 error=-10 AppleSystemPolicy: ASP: Security policy would not allow process DriverKit Kernel: DK: MyUserUSBInterfaceDriver user server timeout dext的 embedded.provisionprofile 已包含： com.apple.developer.driverkit com.apple.developer.driverkit.transport.usb (idVendor: 11977)

Hello! We develop a SAS driver and a service application for DAS devices. When users in our application create a RAID array on the device: On the 1st step, our dext driver mounts a new volume. At this step DiskUtil automatically tries to mount it. As there is no file system on the new volume - the MacOS system popup appears "The disk you attached was not readable by the computer" On the 2nd step our application creates the file system on this new volume. So we do not need this MacOS system popup to appear (as it may frustrate our users). We found a way to disable the global auto mount but this solution also impacts on other devices (which is not good). Are there any other possibilities to prevent the popup "The disk you attached was not readable by the computer" from appearing?

在Developer app中现在注册按钮时置灰等,无法点击,我发送的联系邮件也没有得到回应,有什么办法解决吗

I am developing a macOS virtual audio device using an Audio Server Plug-In (HAL). I want the virtual device to be visible to all applications only when my main app is running, and completely hidden from all apps when the app is closed. The goal is to dynamically control device visibility based on app state without reinstalling the driver.What is the recommended way for the app to notify the HAL plug-in about its running or closed state ? Any guidance on best-practice architecture for this scenario would be appreciated.

Hello! I have app (macos and iPadOS platforms) with empbedded DEXT. The DEXT executable runs fine on both platforms (ver 26.2). Trying to execute from iPad App code: let sysExtWs = OSSystemExtensionsWorkspace.shared let sysExts = try sysExtWs.systemExtensions(forApplicationWithBundleID: appBudleId) but always getting OSSystemExtensionError.Code.missingEntitlement error. Which entitlement am I missing? Thank You!

Why hasn't the watchOS app updated immediately after the iPhone app was updated? It remains stuck in "Installing" status on the Apple Watch.

Have a 2019 Ford Edge w/ Sync 3.4, wired carplay. Worked fine w/ iPhone 16 Pro on iOS 18. Upgraded to iPhone 17 Pro, came w/ iOS 26, carplay hasn't worked since. I've kept trying throughout new iOS 26 releases, lately with iOS 26.3 Public Beta 1, still not working. Have a long running issue with updates and system diagnostics as I've tried over the last few months: FB20739050 There is also a Apple support community thread with issues like this (and a ton of others) - my first post there was https://discussions.apple.com/thread/256138283?answerId=261613103022&sortBy=oldest_first#261613103022 I'm hoping here in the developer forums someone can maybe take a look at the feedback item and various system diagnostics to pin-point the issue. I'm a little concerned it's still not fixed this far into the follow-up point releases of iOS 26. Appreciate any help, thanks! --Chuck

Hi! Following this ticket: https://developer.apple.com/forums/thread/808764?page=1#868010022 Is there any way to use the hardware RFID reading capabilities of an iPhone to read ISO15693 RF tags silently, and without a UI pop-up? Perhaps using other native iOS libraries than the NFC library? If not, is there a way for a business to request this feature be allowed in internally used apps only?

Dear Apple CS, I’m working with NFC ISO15693 tags using NFCTagReaderSession / NFCISO15693Tag, and I’d like to read these tags in the background if possible. Is there any way to read this tag type without triggering the system NFC popup that iOS normally shows? Please note it will not be a public app, the app is meant for internal use for our employees only. is there an option to submit a special request for this use case? Thank you in advance!

We are developing a DriverKit driver on Apple M1. We use the following code to prepare DMA buffer: IODMACommandSpecification dmaSpecification; bzero(&dmaSpecification, sizeof(dmaSpecification)); dmaSpecification.options = kIODMACommandSpecificationNoOptions; dmaSpecification.maxAddressBits = p_dma_mgr->maxAddressBits; kret = IODMACommand::Create(p_dma_mgr->device, kIODMACommandCreateNoOptions, &dmaSpecification, &impl->dma_cmd ); if (kret != kIOReturnSuccess) { os_log(OS_LOG_DEFAULT, "Error: IODMACommand::Create failed! ret=0x%x\n", kret); impl->user_mem.reset(); IOFree(impl, sizeof(*impl)); return ret; } uint64_t flags = 0; uint32_t segmentsCount = 32; IOAddressSegment segments[32]; kret = impl->dma_cmd->PrepareForDMA(kIODMACommandPrepareForDMANoOptions, impl->user_mem.get(), 0, 0, // 0 for entire memory &flags, &segmentsCount, segments ); if (kret != kIOReturnSuccess) { OSSafeReleaseNULL(impl->dma_cmd); impl->user_mem.reset(); IOFree(impl, sizeof(*impl)); os_log(OS_LOG_DEFAULT, "Error: PrepareForDMA failed! ret=0x%x\n", kret); return kret; } I allocated several 8K BGRA video frames, each with a size of 141557760 bytes, and prepared the DMA according to the method mentioned above. The process was successful when the number of frames was 15 or fewer. However, issues arose when allocating 16 frames: Error: PrepareForDMA failed! ret=0xe00002bd By calculating, I found that the total size of 16 video frames exceeds 2GB. Is there such a limitation in DriverKit that the total DMA size cannot exceed 2GB? Are there any methods that would allow me to bypass this restriction so I can use more video frame buffers?

Hello I'm testing an 'age range sharing' feature using the AgeRangeService API in an app we service. I approved 'Age Sharing' during testing. (For your information, my account is an adult account.) For repeat testing, I would like to delete the our app from 'Apps that requested user age information' or cancel the sharing status. However, there doesn't seem to be such a feature. Is there a way I can't find, or is this a feature that Apple doesn't offer?

I created a custom class that inherits from IOUserSCSIPeripheralDeviceType00 in the DriverKit SCSIPeripheralsDriverKit framework. When I attempted to send a vendor-specific command to a USB storage device using the UserSendCDB function of this class instance, the function returned the error: kIOReturnNotPrivileged (iokit_common_err(0x2c1)) // privilege violation However, when using UserSendCDB in the same way to issue standard SCSI commands such as INQUIRY or Test Unit Ready, no error occurred and the returned sense data was valid. Why is UserSendCDB able to send standard SCSI commands successfully, but vendor-specific commands return kIOReturnNotPrivileged? Is there any required entitlement, DriverKit capability, or implementation detail needed to allow vendor-specific CDBs? Below are the entitlements of my DriverKit extension: <dict> <key>com.apple.developer.driverkit.transport.usb</key> <array> <dict> <key>idVendor</key> <integer>[number of vendorid]</integer> </dict> </array> <key>com.apple.developer.driverkit</key> <true/> <key>com.apple.developer.driverkit.allow-any-userclient-access</key> <true/> <key>com.apple.developer.driverkit.allow-third-party-userclients</key> <true/> <key>com.apple.developer.driverkit.communicates-with-drivers</key> <true/> <key>com.apple.developer.driverkit.family.scsicontroller</key> <true/> </dict> If there is any additional configuration or requirement to enable vendor-specific SCSI commands, I would appreciate your guidance. Environment: macOS15.6 M2 MacBook Pro

Hi all, We are migrating a SCSI HBA driver from KEXT to DriverKit (DEXT), with our DEXT inheriting from IOUserSCSIParallelInterfaceController. We've encountered a data corruption issue that is reliably reproducible under specific conditions and are hoping for some assistance from the community. Hardware and Driver Configuration: Controller: LSI 3108 DEXT Configuration: We are reporting our hardware limitations to the framework via the UserReportHBAConstraints function, with the following key settings: // UserReportHBAConstraints... addConstraint(kIOMaximumSegmentAddressableBitCountKey, 0x20); // 32-bit addConstraint(kIOMaximumSegmentCountWriteKey, 129); addConstraint(kIOMaximumByteCountWriteKey, 0x80000); // 512KB Observed Behavior: Direct I/O vs. Buffered I/O We've observed that the I/O behavior differs drastically depending on whether it goes through the system file cache: 1. Direct I/O (Bypassing System Cache) -> 100% Successful When we use fio with the direct=1 flag, our read/write and data verification tests pass perfectly for all file sizes, including 20GB+. 2. Buffered I/O (Using System Cache) -> 100% Failure at >128MB Whether we use the standard cp command or fio with the direct=1 option removed to simulate buffered I/O, we observe the exact same, clear failure threshold: Test Results: File sizes ≤ 128MB: Success. Data checksums match perfectly. File sizes ≥ 256MB: Failure. Checksums do not match, and the destination file is corrupted. Evidence of failure reproduced with fio (buffered_integrity_test.fio, with direct=1 removed): fio --size=128M buffered_integrity_test.fio -> Test Succeeded (err=0). fio --size=256M buffered_integrity_test.fio -> Test Failed (err=92), reporting the following error, which proves a data mismatch during the verification phase: verify: bad header ... at file ... offset 1048576, length 1048576 fio: ... error=Illegal byte sequence Our Analysis and Hypothesis The phenomenon of "Direct I/O succeeding while Buffered I/O fails" suggests the problem may be related to the cache synchronization mechanism at the end of the I/O process: Our UserProcessParallelTask_Impl function correctly handles READ and WRITE commands. When cp or fio (buffered) runs, the WRITE commands are successfully written to the LSI 3108 controller's onboard DRAM cache, and success is reported up the stack. At the end of the operation, to ensure data is flushed to disk, the macOS file system issues an fsync, which is ultimately translated into a SYNCHRONIZE CACHE SCSI command (Opcode 0x35 or 0x91) and sent to our UserProcessParallelTask_Impl. We hypothesize that our code may not be correctly identifying or handling this SYNCHRONIZE CACHE opcode. It might be reporting "success" up the stack without actually commanding the hardware to flush its cache to the physical disk. The OS receives this "success" status and assumes the operation is safely complete. In reality, however, the last batch of data remains only in the controller's volatile DRAM cache and is eventually lost. This results in an incomplete or incorrect file tail, and while the file size may be correct, the data checksum will inevitably fail. Summary Our DEXT driver performs correctly when handling Direct I/O but consistently fails with data corruption when handling Buffered I/O for files larger than 128MB. We can reliably reproduce this issue using fio with the direct=1 option removed. The root cause is very likely the improper handling of the SYNCHRONIZE CACHE command within our UserProcessParallelTask. P.S. This issue did not exist in the original KEXT version of the driver. We would appreciate any advice or guidance on this issue. Thank you.

I am developing a DriverKit driver with the goal of sending vendor-specific commands to a USB storage device. I have successfully created the DriverKit driver, and when I connect the USB storage device, it appears correctly in IORegistryExplorer. My driver class inherits from IOUserSCSIPeripheralDeviceType00 in the SCSIPeripheralsDriverKit framework. I also created a UserClient class that inherits from IOUserClient, and from its ExternalMethod I tried sending an INQUIRY command as a basic test to confirm that command transmission works. However, the device returns an ILLEGAL REQUEST (Sense Key 0x5 / ASC 0x20). Could someone advise what I might be doing wrong? Below are the logs output from the driver: 2025-11-14 21:00:43.573730+0900 0x26e9 Default 0x0 0 0 kernel: (SampleDriverKitApp.SampleDriverKitDriver.dext) [DEBUG] Driver - NewUserClient() - Finished. 2025-11-14 21:00:43.573733+0900 0x26e9 Default 0x0 0 0 kernel: (SampleDriverKitApp.SampleDriverKitDriver.dext) [DEBUG] UserClient - Start() 2025-11-14 21:00:43.573807+0900 0x26e9 Default 0x0 0 0 kernel: (SampleDriverKitApp.SampleDriverKitDriver.dext) [DEBUG] UserClient - Start() - Finished. 2025-11-14 21:00:43.574249+0900 0x26e9 Default 0x0 0 0 kernel: (SampleDriverKitApp.SampleDriverKitDriver.dext) [DEBUG] UserClient - ExternalMethod() called 2025-11-14 21:00:43.574258+0900 0x26e9 Default 0x0 0 0 kernel: (SampleDriverKitApp.SampleDriverKitDriver.dext) [DEBUG] UserClient - ----- SCSICmdINQUIRY ----- 2025-11-14 21:00:43.574268+0900 0x26e9 Default 0x0 0 0 kernel: (SampleDriverKitApp.SampleDriverKitDriver.dext) [DEBUG] UserClient - command.fRequestedByteCountOfTransfer = 512 2025-11-14 21:00:43.575980+0900 0x26e9 Default 0x0 0 0 kernel: (SampleDriverKitApp.SampleDriverKitDriver.dext) [DEBUG] UserClient - SCSICmdINQUIRY() UserSendCDB fCompletionStatus = 0x0 2025-11-14 21:00:43.575988+0900 0x26e9 Default 0x0 0 0 kernel: (SampleDriverKitApp.SampleDriverKitDriver.dext) [DEBUG] UserClient - SCSICmdINQUIRY() UserSendCDB fServiceResponse = 0x2 2025-11-14 21:00:43.575990+0900 0x26e9 Default 0x0 0 0 kernel: (SampleDriverKitApp.SampleDriverKitDriver.dext) [DEBUG] UserClient - SCSICmdINQUIRY() UserSendCDB fSenseDataValid = 0x1 2025-11-14 21:00:43.575992+0900 0x26e9 Default 0x0 0 0 kernel: (SampleDriverKitApp.SampleDriverKitDriver.dext) [DEBUG] UserClient - SCSICmdINQUIRY() UserSendCDB VALID_RESPONSE_CODE = 0x70 2025-11-14 21:00:43.575994+0900 0x26e9 Default 0x0 0 0 kernel: (SampleDriverKitApp.SampleDriverKitDriver.dext) [DEBUG] UserClient - SCSICmdINQUIRY() UserSendCDB SENSE_KEY = 0x5 2025-11-14 21:00:43.575996+0900 0x26e9 Default 0x0 0 0 kernel: (SampleDriverKitApp.SampleDriverKitDriver.dext) [DEBUG] UserClient - SCSICmdINQUIRY() UserSendCDB ADDITIONAL_SENSE_CODE = 0x20 2025-11-14 21:00:43.575998+0900 0x26e9 Default 0x0 0 0 kernel: (SampleDriverKitApp.SampleDriverKitDriver.dext) [DEBUG] UserClient - SCSICmdINQUIRY() UserSendCDB ADDITIONAL_SENSE_CODE_QUALIFIER = 0x0 Here is the UserClient class: class SampleDriverKitUserClient: public IOUserClient { public: virtual bool init(void) override; virtual kern_return_t Start(IOService* provider) override; virtual kern_return_t Stop(IOService* provider) override; virtual void free(void) override; virtual kern_return_t ExternalMethod( uint64_t selector, IOUserClientMethodArguments* arguments, const IOUserClientMethodDispatch* dispatch, OSObject* target, void* reference) override; void SCSICmdINQUIRY(SampleDriverKitDriver *driver) LOCALONLY; }; Here is the part that sends the INQUIRY command: void SampleDriverKitUserClient::SCSICmdINQUIRY(SampleDriverKitDriver *driver) { kern_return_t kr = KERN_SUCCESS; SCSIType00OutParameters command = {}; UInt8 dataBuffer[512] = {0}; SCSI_Sense_Data senseData = {0}; Log("----- SCSICmdINQUIRY -----"); SetCommandCDB(&command.fCommandDescriptorBlock, 0x12, 0x00, 0x00, 0x24, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00); command.fLogicalUnitNumber = 0; command.fTimeoutDuration = 10000; // milliseconds command.fRequestedByteCountOfTransfer = sizeof(dataBuffer); Log("command.fRequestedByteCountOfTransfer = %lld", command.fRequestedByteCountOfTransfer); command.fBufferDirection = kIOMemoryDirectionIn; command.fDataTransferDirection = kSCSIDataTransfer_FromTargetToInitiator; command.fDataBufferAddr = reinterpret_cast<uint64_t>(dataBuffer); command.fSenseBufferAddr = reinterpret_cast<uint64_t>(&senseData); command.fSenseLengthRequested = sizeof(senseData); if( driver ) { SCSIType00InParameters response = {}; kr = driver->UserSendCDB(command, &response); if( kr != KERN_SUCCESS ) { Log("SCSICmdINQUIRY() UserSendCDB failed (0x%x)", kr); return; } Log("SCSICmdINQUIRY() UserSendCDB fCompletionStatus = 0x%x", response.fCompletionStatus); Log("SCSICmdINQUIRY() UserSendCDB fServiceResponse = 0x%x", response.fServiceResponse); Log("SCSICmdINQUIRY() UserSendCDB fSenseDataValid = 0x%x", response.fSenseDataValid); Log("SCSICmdINQUIRY() UserSendCDB VALID_RESPONSE_CODE = 0x%x", senseData.VALID_RESPONSE_CODE); Log("SCSICmdINQUIRY() UserSendCDB SENSE_KEY = 0x%x", senseData.SENSE_KEY); Log("SCSICmdINQUIRY() UserSendCDB ADDITIONAL_SENSE_CODE = 0x%x", senseData.ADDITIONAL_SENSE_CODE); Log("SCSICmdINQUIRY() UserSendCDB ADDITIONAL_SENSE_CODE_QUALIFIER = 0x%x", senseData.ADDITIONAL_SENSE_CODE_QUALIFIER); if( response.fServiceResponse == kSCSIServiceResponse_TASK_COMPLETE ) { Log("SCSICmdINQUIRY() UserSendCDB complete success!!"); } for( int i=0; i < 5; i++ ) { Log("data [%04d]=0x%x [%04d]=0x%x [%04d]=0x%x [%04d]=0x%x [%04d]=0x%x [%04d]=0x%x [%04d]=0x%x [%04d]=0x%x", i*8+0, dataBuffer[i*8+0], i*8+1, dataBuffer[i*8+1], i*8+2, dataBuffer[i*8+2], i*8+3, dataBuffer[i*8+3], i*8+4, dataBuffer[i*8+4], i*8+5, dataBuffer[i*8+5], i*8+6, dataBuffer[i*8+6], i*8+7, dataBuffer[i*8+7] ); } char vendorID[9] = {0}; memcpy(vendorID, &dataBuffer[8], 8); Log("vendorID = %s",vendorID); char productID[17] = {0}; memcpy(productID, &dataBuffer[16], 16); Log("productID = %s",productID); } } My environment is: MacBook Pro (M2), macOS 15.6 If anyone has insight into what causes the ILLEGAL REQUEST, or what I am missing when using IOUserSCSIPeripheralDeviceType00 and UserSendCDB, I would greatly appreciate your help. Thank you.

Hello everyone, We are migrating a KEXT storage driver to DriverKit. In our KEXT, we use a "one LUN = one Target" model and successfully create multiple targets in a loop during initialization. We are now trying to replicate this architecture in our DEXT. The issue is that only Target 0 is fully probed and mounted. For Target 1, the lifecycle silently stops after the first TEST UNIT READY command is successfully acknowledged. The macOS SCSI layer never sends any subsequent probe commands (like INQUIRY) to this target. The failure sequence for Target 1, observed from our logs (regardless of whether Target 0 is created), is as follows: AsyncCreateTargetForID(1) -> UserInitializeTargetForID(1) (Succeeds) UserProcessParallelTask(Target: 1, Opcode: TUR) (Succeeds) The DEXT correctly acknowledges the TUR command for Target 1 by returning kSCSITaskStatus_CHECK_CONDITION with UNIT ATTENTION in the Sense Data (Succeeds) <-- Breakpoint --> UserProcessParallelTask(Target: 1, Opcode: INQUIRY) (Never happens) Through log comparison, we have confirmed that the DEXT's response to the TUR command for Target 1 is identical to the successful KEXT's response. We have tried creating only Target 1 (skipping Target 0 entirely), but the behavior is exactly the same -> the probe still stalls after the TUR. We initially suspected a race condition caused by consecutive calls to AsyncCreateTargetForID(). We attempted several methods to ensure that targets are created sequentially, such as trying to build a "creation chain" using OSAction completion handlers. However, these attempts were unsuccessful due to various compilation errors and API misunderstandings. In any case, this "race condition" theory was ultimately disproven by our experiment where creating only Target 1 still resulted in failure. We would like to ask two questions: Is our inability to have a Target ID greater than 0 fully probed by macOS a bug in our own code, or could there be another reason we are unaware of? If we do indeed need a "one-after-another" creation mechanism for AsyncCreateTargetForID, what is the correct way to implement a "chained creation" using OSAction completion handlers in DriverKit? Thank you for any help or guidance. Best Regards, Charles

Hello everyone, We are in the process of migrating a high-performance storage KEXT to DriverKit. During our initial validation phase, we noticed a performance gap between the DEXT and the KEXT, which prompted us to try and optimize our I/O handling process. Background and Motivation: Our test hardware is a RAID 0 array of two HDDs. According to AJA System Test, our legacy KEXT achieves a write speed of about 645 MB/s on this hardware, whereas the new DEXT reaches about 565 MB/s. We suspect the primary reason for this performance gap might be that the DEXT, by default, uses a serial work-loop to submit I/O commands, which fails to fully leverage the parallelism of the hardware array. Therefore, to eliminate this bottleneck and improve performance, we configured a dedicated parallel dispatch queue (MyParallelIOQueue) for the UserProcessParallelTask method. However, during our implementation attempt, we encountered a critical issue that caused a system-wide crash. The Operation Causing the Panic: We configured MyParallelIOQueue using the following combination of methods: In the .iig file: We appended the QUEUENAME(MyParallelIOQueue) macro after the override keyword of the UserProcessParallelTask method declaration. In the .cpp file: We manually created a queue with the same name by calling the IODispatchQueue::Create() function within our UserInitializeController method. The Result: This results in a macOS kernel panic during the DEXT loading process, forcing the user to perform a hard reboot. After the reboot, checking with the systemextensionsctl list command reveals the DEXT's status as [activated waiting for user], which indicates that it encountered an unrecoverable, fatal error during its initialization. Key Code Snippets to Reproduce the Panic: In .iig file - this was our exact implementation: class DRV_MAIN_CLASS_NAME: public IOUserSCSIParallelInterfaceController { public: virtual kern_return_t UserProcessParallelTask(...) override QUEUENAME(MyParallelIOQueue); }; In .h file: struct DRV_MAIN_CLASS_NAME_IVars { // ... IODispatchQueue* MyParallelIOQueue; }; In UserInitializeController implementation: kern_return_t IMPL(DRV_MAIN_CLASS_NAME, UserInitializeController) { // ... // We also included code to manually create the queue. kern_return_t ret = IODispatchQueue::Create("MyParallelIOQueue", kIODispatchQueueReentrant, 0, &ivars->MyParallelIOQueue); if (ret != kIOReturnSuccess) { // ... error handling ... } // ... return kIOReturnSuccess; } Our Question: What is the officially recommended and most stable method for configuring UserProcessParallelTask_Impl() to use a parallel I/O queue? Clarifying this is crucial for all developers pursuing high-performance storage solutions with DriverKit. Any explanation or guidance would be greatly appreciated. Best Regards, Charles