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 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 everyone, We're trying to prepare a DriverKit App for a client test, and we've run into an unavoidable signing conflict that seems to be caused by the Xcode Archive process itself. Background & Environment: Environment: macOS 15.6.1, Xcode 16.4 Our project consists of a main App Target and a DEXT Target. Both the Debug and Release configurations for both targets are set to Xcode's default: Automatically manage signing. Our developer account holds a valid, active Developer ID Application (With Kext) certificate, which we use for signing our legacy KEXT. The Action That Triggers Failure: From this clean state, we execute Product -> Archive. The Archive process fails during the signing validation phase and presents the following three errors, completely halting the process: There is a problem with the request entity - You already have a current Developer ID Application Managed (With Kext) certificate... No profiles for 'com.company.Acxxx.driver' were found... No profiles for 'com.company.Acxxx.app' were found... This error seems to indicate that the Xcode Archive process: Ignores the project's Release configuration (even the default 'Auto' setting). Attempts to automatically create a new, standard Developer ID certificate for us. This action conflicts with the existing (With Kext) certificate in our account, causing the entire Archive process to fail. The "Failed Experiment" to Resolve This: To work around this automation conflict, we tried the solution: configuring a fully manual signing process for the Release configuration to explicitly tell Xcode to use our existing KEXT certificate. Our Steps: We disabled automatic signing for both the App and DEXT targets for the Release configuration and manually assigned the Developer ID Provisioning Profiles created for our Developer ID (With Kext) certificate. The New Problem: After doing this, the Signing Certificate field for the DEXT Target's Signing & Capabilities interface now shows None, accompanied by the misleading warning about needing a DriverKit development profile. The Outcome: This None issue now prevents us from even starting the Archive process, as the project fails to build due to the incorrect signing configuration. We've tried every debugging step — including rebuilding profiles, validating the keychain, and clearing caches — but nothing resolves this None issue. Our Dilemma: State A (Fully Automatic Signing): The Archive process fails due to the KEXT certificate conflict. State B (Manual Release Signing): The project fails to build due to the Signing Certificate: None issue, preventing us from initiating an Archive. For a development team holding a KEXT Developer ID certificate, how should an Xcode project be configured when migrating to DriverKit, so that the Archive process: Does not trigger the flawed automation logic that attempts to create a new certificate? And, does not fall into the Signing Certificate: None configuration trap? Related Forum Threads We've Studied: https://developer.apple.com/forums/thread/781932 https://developer.apple.com/forums/thread/751490 https://developer.apple.com/forums/thread/767152 https://developer.apple.com/forums/thread/721563 Best Reagrds, Charles

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

Hi everyone, We are in the process of migrating a legacy KEXT for our external multi-disk RAID enclosure to the modern DriverKit framework. During the performance validation of our KEXT, we observed a large and consistent maximum throughput difference between Intel-based Macs and Apple Silicon-based Macs. We would like to share our findings and hope to discuss with others in the community to see if you have had similar experiences that could confirm or correct our understanding. The Observation: A Consistent Performance Gap When using the exact same external RAID hardware (an 8-HDD RAID 5 array), driven by our mature KEXT, we see the following results in high-throughput benchmarks (AJA System Test, large sequential writes): On a 2020 Intel-based Mac: We consistently achieve a throughput of ~2500 MB/s. On modern M-series Macs (from M1 to M4): The throughput is consistently capped at ~1500 MB/s. This performance difference of nearly 40% is significant and is present across the entire Apple Silicon product line. Our Hypothesis: A Shift in Architectural Design Philosophy Since the KEXT and external hardware are identical in both tests, we believe this performance difference is not a bug but a fundamental platform architecture distinction. Our hypothesis is as follows: 1. The Intel Mac Era ("Dedicated Throughput") The Intel-based Macs we tested use a dedicated, discrete Intel Thunderbolt controller chip. This chip has its own dedicated PCIe lanes and resources, and its design appears to be singularly focused on maximizing raw, sustained data throughput for external peripherals. 2. The Apple Silicon Era ("Integrated Efficiency") In contrast, M-series Macs use a deeply integrated I/O controller inside the SoC. This controller must share resources, such as the total unified memory bandwidth and the chip's overall power budget, with all other functional units (CPU, GPU, etc.). We speculate that the design priority for this integrated I/O controller has shifted from "maximizing single-task raw throughput" to "maximizing overall system efficiency, multi-task responsiveness, and low latency." As a result, in a pure, single-task storage benchmark, its performance ceiling may be lower than that of the older, dedicated-chip architecture. Our Question to the Community: Is our understanding correct? Have other developers of high-performance storage drivers or peripherals also observed a similar performance ceiling for external storage on Apple Silicon Macs, when compared to high-end Intel Macs? We believe that understanding this as a deliberate architectural trade-off is crucial for setting realistic performance targets for our DEXT. Our current goal has been adjusted to have our DEXT match the KEXT's ~1500 MB/s on the M-series platform. Any insights, confirmations, or corrections from the community or Apple engineers would be greatly appreciated. Thank you very much! Charles

Hello everyone, We are migrating our KEXT for a Thunderbolt storage device to a DEXT based on IOUserSCSIParallelInterfaceController. We've run into a fundamental issue where the driver's behavior splits based on the I/O source: high-level I/O from the file system (e.g., Finder, cp) is mostly functional (with a minor ls -al sorting issue for Traditional Chinese filenames), while low-level I/O directly to the block device (e.g., diskutil) fails or acts unreliably. Basic read/write with dd appears to be mostly functional. We suspect that our DEXT is failing to correctly register its full device "personality" with the I/O Kit framework, unlike its KEXT counterpart. As a result, low-level I/O requests with special attributes (like cache synchronization) sent by diskutil are not being handled correctly by the IOUserSCSIParallelInterfaceController framework of our DEXT. Actions Performed & Relevant Logs 1. Discrepancy: diskutil info Shows Different Device Identities for DEXT vs. KEXT For the exact same hardware, the KEXT and DEXT are identified by the system as two different protocols. KEXT Environment: Device Identifier: disk5 Protocol: Fibre Channel Interface ... Disk Size: 66.0 TB Device Block Size: 512 Bytes DEXT Environment: Device Identifier: disk5 Protocol: SCSI SCSI Domain ID: 2 SCSI Target ID: 0 ... Disk Size: 66.0 TB Device Block Size: 512 Bytes 2. Divergent I/O Behavior: Partial Success with Finder/cp vs. Failure with diskutil High-Level I/O (Partially Successful): In the DEXT environment, if we operate on an existing volume (e.g., /Volumes/MyVolume), file copy operations using Finder or cp succeed. Furthermore, the logs we've placed in our single I/O entry point, UserProcessParallelTask_Impl, are triggered. Side Effect: However, running ls -al on such a volume shows an incorrect sorting order for files with Traditional Chinese names (they appear before . and ..). Low-Level I/O (Contradictory Behavior): In the DEXT environment, when we operate directly on the raw block device (/dev/disk5): diskutil partitionDisk ... -> Fails 100% of the time with the error: Error: -69825: Wiping volume data to prevent future accidental probing failed. dd command -> Basic read/write operations appear to work correctly (a write can be immediately followed by a read within the same DEXT session, and the data is correct). 3. Evidence of Cache Synchronization Failure (Non-deterministic Behavior) The success of the dd command is not deterministic. Cross-environment tests prove that its write operations are unreliable: First Test: In the DEXT environment, write a file with random data to /dev/disk5 using dd. Reboot into the KEXT environment. Read the data back from /dev/disk5 using dd. The result is a file filled with all zeros. Conclusion: The write operation only went to the hardware cache, and the data was lost upon reboot. Second Test: In the DEXT environment, write the same random file to /dev/disk5 using dd. Key Variable: Immediately after, still within the DEXT environment, read the data back once for verification. The content is correct! Reboot into the KEXT environment. Read the data back from /dev/disk5. This time, the content is correct! Conclusion: The additional read operation in the second test unintentionally triggered a hardware cache flush. This proves that the dd (in our DEXT) write operation by itself does not guarantee synchronization, making its behavior unreliable. Our Problem Based on the observations above, we have the conclusion: High-Level Path (triggered by Finder/cp): When an I/O request originates from the high-level file system, the framework seems to enter a fully-featured mode. In this mode, all SCSI commands, including READ/WRITE, INQUIRY, and SYNCHRONIZE CACHE, are correctly packaged and dispatched to our UserProcessParallelTask_Impl entry point. Therefore, Finder operations are mostly functional. Low-Level Path (triggered by dd/diskutil): When an I/O request originates from the low-level raw block device layer: The most basic READ/WRITE commands can be dispatched (which is why dd appears to work). However, critical management commands, such as INQUIRY and SYNCHRONIZE CACHE, are not being correctly dispatched or handled. This leads to the incorrect device identification in diskutil info and the failure of diskutil partitionDisk due to its inability to confirm cache synchronization. We would greatly appreciate any guidance, suggestions, or insights on how to resolve this discrepancy. Specifically, what is the recommended approach within DriverKit to ensure that a DEXT based on IOUserSCSIParallelInterfaceController can properly declare its capabilities and handle both high-level and low-level I/O requests uniformly? Thank you. Charles

Hello everyone, I am migrating a KEXT for a SCSI PCI RAID controller (LSI 3108 RoC) to DriverKit (DEXT). While the DEXT loads successfully, I'm facing a DMA issue: an INQUIRY command results in a 0-byte disk because the data buffer received by the DEXT is all zeros, despite our firmware logs confirming that the correct data was prepared and sent. We have gathered detailed forensic evidence and would appreciate any insights from the community. Detailed Trace of a Failing INQUIRY Command: 1, DEXT Dispatches the Command: Our UserProcessParallelTask implementation correctly receives the INQUIRY task. Logs show the requested transfer size is 6 bytes, and the DEXT obtains the IOVA (0x801c0000) to pass to the hardware. DEXT Log: [UserProcessParallelTask_Impl] --- FORENSIC ANALYSIS --- [UserProcessParallelTask_Impl] fBufferIOVMAddr = 0x801c0000 [UserProcessParallelTask_Impl] fRequestedTransferCount = 6 2, Firmware Receives IOVA and Prepares Correct Data: A probe in our firmware confirms that the hardware successfully received the correct IOVA and the 6-byte length requirement. The firmware then prepares the correct 6-byte INQUIRY response in its internal staging buffer. Firmware Logs: -- [FIRMWARE PROBE: INCOMING DMA DUMP] -- Host IOVA (High:Low) = 0x00000000801c0000 DataLength in Header = 6 (0x6) --- [Firmware Outgoing Data Dump from go_inquiry] --- Source Address: 0x228BB800, Length: 6 bytes 0x0000: 00 00 05 12 1F 00 3, Hardware Reports a Successful Transfer, but Data is Lost: After the firmware initiates the DMA write to the Host IOVA, the hardware reports a successful transfer of 6 bytes back to our DEXT. DEXT Completion Log: [AME_Host_Normal_Handler_SCSI_Request] [TaskID: 200] COMPLETING... [AME_Host_Normal_Handler_SCSI_Request] Hardware Transferred = 6 bytes [AME_Host_Normal_Handler_SCSI_Request] - ReplyStatus = SUCCESS (0x0) [AME_Host_Normal_Handler_SCSI_Request] - SCSIStatus = SUCCESS (0x0) The Core Contradiction: Despite the firmware preparing the correct data and the hardware reporting a successful DMA transfer, the fDataBuffer in our DEXT remains filled with zeros. The 6 bytes of data are lost somewhere between the PCIe bus and host memory. This "data-in-firmware, zeros-in-DEXT" phenomenon leads us to believe the issue lies in memory address translation or a system security policy, as our legacy KEXT works perfectly on the same hardware. Compared to a KEXT, are there any known, stricter IOMMU/security policies for a DEXT that could cause this kind of "silent write failure" (even with a correct IOVA)? Alternatively, what is the correct and complete expected workflow in DriverKit for preparing an IOMemoryDescriptor* fDataBuffer (received in UserProcessParallelTask) for a PCI hardware device to use as a DMA write target? Any official documentation, examples, or advice on the IOMemoryDescriptor to PCI Bus Address workflow would be immensely helpful. Thank you. Charles

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

So when you are on tik tok if i press the comment function the phone freezes there you cant press back or go back to a video you have to restart the application

Hello everyone, I’m working on implementing hardware interrupt handling in DriverKit and came across the InterruptOccurred method in IOInterruptDispatchSource. I noticed that its declaration ends with a TYPE macro: virtual void InterruptOccurred(OSAction* action, uint64_t count, uint64_t time) TYPE(IOInterruptDispatchSource::InterruptOccurred); This structure seems similar to how Timer Events are set up, where an event is linked to a callback and triggered by a timer. I’m attempting to use a similar approach, but for hardware-triggered interrupts rather than timer events. I’m currently in the trial-and-error phase of the implementation, but if anyone has a working example or reference on how to properly implement and register InterruptOccurred, it would be greatly appreciated! Best regards, Charles

Hi everyone, I was following the Video Modernize PCI and SCSI drivers with DriverKit and the Document to implement UserMapHBAData(), and here’s my current implementation: // kern_return_t DRV_MAIN_CLASS_NAME::UserMapHBAData_Impl(uint32_t *uniqueTaskID) kern_return_t IMPL(DRV_MAIN_CLASS_NAME, UserMapHBAData) { Log("UserMapHBAData() - Start"); // Define the vm_page_size explicitly const uint32_t vm_page_size = 4096; kern_return_t ret; IOBufferMemoryDescriptor *buffer = nullptr; IOMemoryMap *memMap = nullptr; void *taskData = nullptr; // Create a buffer for HBA-specific task data ret = IOBufferMemoryDescriptor::Create(kIOMemoryDirectionOutIn, ivars->fTaskDataSize, vm_page_size, &buffer); __Require((kIOReturnSuccess == ret), Exit); // Map memory to the driver extension's memory space ret = buffer->CreateMapping(0, 0, 0, 0, 0, &memMap); __Require((kIOReturnSuccess == ret), Exit); // Retrieve mapped memory address taskData = reinterpret_cast<void *>(memMap->GetAddress()); __Require(taskData, Exit); // WARNING: Potential leak of an object stored into 'buffer' // WARNING: Potential leak of an object stored into 'memMap' // Assign a unique task ID ivars->fTaskID++; // ERROR: No member named 'fTaskID' in 'DriverKitAcxxx_IVars' ivars->fTaskArray[ivars->fTaskID] = taskData; *uniqueTaskID = ivars->fTaskID; Log("UserMapHBAData() - End"); return kIOReturnSuccess; Exit: // Cleanup in case of failure if (memMap) { memMap->free(); // Correct method for releasing memory maps } if (buffer) { buffer->free(); // Correct method for releasing buffer memory } LogErr("ret = 0x%0x", ret); Log("UserMapHBAData() - End"); return ret; } For reference, in KEXT, memory allocation is typically done using: IOBufferMemoryDescriptor *buffer = IOBufferMemoryDescriptor::inTaskWithOptions( kernel_task, // Task in which memory is allocated kIODirectionOutIn, // Direction (read/write) 1024, // Size of the buffer in bytes 4); // Alignment requirements However, after installing the dext, macOS hangs, and I have to do a hardware reset. After rebooting, the sysctl list output shows: % sectl list 1 extension(s) --- com.apple.system_extension.driver_extension enabled active teamID bundleID (version) name [state] * - com.accusys.DriverKitAcxxx (5.0/11) com.accusys.DriverKitAcxxx [activated waiting for user] Questions: What could be causing macOS to halt? How should I approach debugging and resolving this issue? Looking forward to your insights, any suggestions would be greatly appreciated! Best regards, Charles

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

Hello Everyone, I am trying to create a Fake SCSI target based on SCSIControllerDriverKit.framework and inherent from IOUserSCSIParallelInterfaceController, here is the code kern_return_t IMPL(DRV_MAIN_CLASS_NAME, Start) { ... // Programmatically create a null SCSI Target SCSIDeviceIdentifier nullTargetID = 0; // Example target ID, adjust as needed ret = UserCreateTargetForID(nullTargetID, nullptr); if (ret != kIOReturnSuccess) { Log("Failed to create Null SCSI Target for ID %llu", nullTargetID); return ret; } ... } According the document UserCreateTargetForID, after creating a TargetID successfully, the framework will call the UserInitializeTargetForID() The document said: As part of the UserCreateTargetForID call, the kernel calls several APIs like UserInitializeTargetForID which run on the default dispatch queue of the dext. But after UserCreateTargetForID created, why the UserInitializeTargetForID() not be invoked automatically? Here is the part of log show init() - Start init() - End Start() - Start Start() - try 1 times UserCreateTargetForID() - Start Allocating resources for Target ID 0 UserCreateTargetForID() - End Start() - Finished. UserInitializeController() - Start - PCI vendorID: 0x14d6, deviceID: 0x626f. - BAR0: 0x1, BAR1: 0x200004. - GetBARInfo() - BAR1 - MemoryIndex: 0, Size: 262144, Type: 0. UserInitializeController() - End UserStartController() - Start - msiInterruptIndex : 0x00000000 - interruptType info is 0x00010000 - PCI Dext interrupt final value, return status info is 0x00000000 UserStartController() - End Any assistance would be greatly appreciated! Thank you in advance for your support. Best regards, Charles

Hello Everyone, I am trying to develop a DriverKit for RAID system, using PCIDriverKit & SCSIControllerDriverKit framework. The driver can detect the Vendor ID and Device ID. But before communicating to the RAID system, I would like to simulate a virtual Volume using a memory block to talk with macOS. In the UserInitializeController(), I allocated a 512K memory for a IOBufferMemoryDescriptor* volumeBuffer, but fail to use Map() to map memory for volumeBuffer. result = ivars->volumeBuffer->Map( 0, // Options: Use default 0, // Offset: Start of the buffer ivars->volumeSize, // Length: Must not exceed buffer size 0, // Flags: Use default nullptr, // Address space: Default address space &mappedAddress // Output parameter ); Log("Memory mapped completed at address: 0x%llx", mappedAddress); // this line never run The Log for Map completed never run, just restart to run the Start() and makes this Driver re-run again and again, in the end, the driver eat out macOS's memory and system halt. Are the parameters for Map() error? or I should not put this code in UserInitializeController()? Any help is appreciated! Thanks in advance. Charles

Hi Everybody, Follow Communicating between a DriverKit extension and a client app to migrate our kext to dext. The dext might have been loaded successfully by using the command systemextensionsctl list, the dext is loaded and enabled. % sectl list 1 extension(s) --- com.apple.system_extension.driver_extension enabled active teamID bundleID (version) name [state] * * K3TDMD9Y6B com.accusys.scsidriver (1.0/1) com.accusys.scsidriver [activated enabled] We try to use the CppUserClient.cpp to communicate with the dext, but can not get the dext service. The debug message as below: Failed opening service with error: 0xe00002c7. Here is the part of CppUserClient.cpp static const char* dextIdentifier = "com.accusys.scsidriver"; kern_return_t ret = kIOReturnSuccess; io_iterator_t iterator = IO_OBJECT_NULL; io_service_t service = IO_OBJECT_NULL; ret = IOServiceGetMatchingServices(kIOMasterPortDefault, IOServiceMatching("IOUserServer"), &iterator); printf("dextIdentifier = %s\n", dextIdentifier); printf("IOServiceNameMatching return = %d\n", ret); if (ret != kIOReturnSuccess) { printf("Unable to find service for identifier with error: 0x%08x.\n", ret); PrintErrorDetails(ret); } printf("Searching for dext service...\n"); while ((service = IOIteratorNext(iterator)) != IO_OBJECT_NULL) { // Open a connection to this user client as a server to that client, and store the instance in "service" ret = IOServiceOpen(service, mach_task_self_, kIOHIDServerConnectType, &connection); if (ret == kIOReturnSuccess) { printf("\tOpened service.\n"); break; } else { printf("\tFailed opening service with error: 0x%08x.\n", ret); } IOObjectRelease(service); } IOObjectRelease(iterator); if (service == IO_OBJECT_NULL) { printf("Failed to match to device.\n"); return EXIT_FAILURE; } The console output message is dextIdentifier = com.accusys.scsidriver IOServiceNameMatching return = 0 Searching for dext service... Failed opening service with error: 0xe00002c7. Failed opening service with error: 0xe00002c7. Failed opening service with error: 0xe00002c7. Failed opening service with error: 0xe00002c7. Failed to match to device. Here is the log show message fredapp start UserInitializeController pcitest: fredapp pci vendorID: 14d6 deviceID: 626f fredapp nnnnnew configuaration read32 0x10 info: 1 fredapp nnnnnew configuaration read32 0x14 info: 80100004 fredapp new 128 before enable busmaster ReqMSGport_info 0x00000040 : fffff pcitest: fredapp 131 pci ConfigurationRead16 busmaster value 0 pcitest: fredapp 134 Enable BusMaster and IO space done...... locate 139 fredapp MemoryWrite32 function done...... fredapp new 143 after enable busmaster ReqMSGport_info 0x00000040 : 0 fredapp newwww before GetBARInfo memoryIndex1 info is: 5 fredapp GetBARInfo 1 kernel return status is: 0 fredapp GetBARInfo memoryIndex1 info is: 0 fredapp GetBARInfo barSize1 info is: 262144 fredapp GetBARInfo barType1 info is: 0 fredapp GetBARInfo result0 info is: 3758097136 fredapp GetBARInfo memoryIndex0 info is: 0 fredapp GetBARInfo barSize0 info is: 0 fredapp GetBARInfo barType0 info is: 0 pcitest: newwww fredapp againnnn test ReqMSGport info: 8 fredapp Start MPIO_Init_Prepare fredapp end MPIO_Init_Prepare. fredapp call 741 Total_memory_size: 1bb900 fredapp Start MemoryAllocationForAME_Module. fredapp IOBufferMemoryDescriptor create return status info is kIOReturnSuc fredapp IOBufferMemoryDescriptor virtualAddressSegment address info: 0x1 fredapp virtualAddressSegment length info: 0x00080000 fredapp end IOBufferMemoryDescriptor Create. fredapp dmaSpecification maxAddressBits: 0x00000000 fredapp dmaSpecification maxAddressBits: 0x00000027 fredapp IODMACommand create return status info is kIOReturnSuccess fredapp end IODMACommand Create. fredapp PrepareForDMA return status info is kIOReturnSuccess fredapp PrepareForDMA return status info is 0x00000000 fredapp Allocate memory PrepareforDMA return flags info: 0x00000003 fredapp Allocate memory PrepareforDMA return segmentsCount info: 0x00000 fredapp Allocate memory PrepareforDMA return physicalAddressSegment info: fredapp IOBufferMemoryDescriptor virtualAddressSegment address info-2: 0 fredapp verify data success init() - Finished. fredapp start UserGetDMASpecification fredapp end UserGetDMASpecification fredapp start UserMapHBAData fredapp end UserMapHBAData fredapp start UserStartController fredapp interruptType info is 0x00010000 fredapp PCI Dext interrupt final value return status info is 0x00000000 Any suggestions? Best Regards, Charles