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?

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!

Hi, On macOS 11 and earlier versions, we provided users with the following script to uninstall our kext driver: sudo pkgutil --only-files --files com.magewell.ProCapture | tr '\n' '\0' | xargs -n 1 -0 sudo rm -vf sudo pkgutil --only-dirs --files com.magewell.ProCapture | grep ProCapture[^/]*$ | tr '\n' '\0' | xargs -n 1 -0 sudo rm -rvf sudo pkgutil --forget com.magewell.ProCapture sudo kextcache -system-caches However, this script no longer works on macOS 13 and returns the following error: It looks like you're trying to update the system caches. As of macOS 11, the personality cache is no longer in use for keeping kext matching information up-to-date. For more information, see `man kmutil`. This indicates we can no longer use kextcache -system-caches to clear our driver cache. This creates an issue where even after installing the new dext driver, the dext driver cannot run due to the presence of the old kext driver. We've tried various methods but haven't been able to completely uninstall the old kext driver - after every new system update, the old kext reappears. The specific process is as follows: This is the sequence I followed in my latest test - Device is running macOS 13 Ventura w/ 4247 Pro Capture kext driver installed kmutil inspect | grep -i magewell - this returns references to the kext files in /Library/Extensions, which is expected because I have not yet removed the 4247 kext driver - then I ran the following combination of your removal script and my removal steps: cd / sudo rm -r /Library/Extensions/ProCaptureDriver.kext sudo rm -r /Library/Extensions/ProCaptureEvent.kext sudo rm /System/Volumes/Preboot/*/boot/*/System/Library/Caches/com.apple.kernelcaches/kernelcache.auxkc* sudo pkgutil --only-files --files com.magewell.ProCapture | tr '\n' '\0' | xargs -n 1 -0 sudo rm -vf sudo pkgutil --only-dirs --files com.magewell.ProCapture | grep ProCapture[^/]*$ | tr '\n' '\0' | xargs -n 1 -0 sudo rm -rvf sudo pkgutil --forget com.magewell.ProCapture sudo kextcache --clear-staging sudo kcditto sudo kmutil install --update-preboot sudo shutdown -r now - After this I ran 'kmutil inspect | grep -i magewell' and got no results, which seems good but... - then I ran the upgrade to macOS 15.7 Sequoia - Afterwards I ran 'kmutil inspect | grep -i magewell' and it returned references to the old /Library/Extensions kexts again, although the files no longer exist in /Library/Extensions - I then ran my cleanup process again (slightly different for Sequoia-available commands): sudo rm /System/Volumes/Preboot/*/boot/*/System/Library/Caches/com.apple.kernelcaches/kernelcache.auxkc* sudo kextcache --clear-staging sudo kmutil rebuild sudo kcditto sudo kmutil install --update-preboot sudo shutdown -r now - Then I ran 'kmutil inspect | grep -i magewell' and got no results again - As a next test I ran a minor update to macOS 15.7.1, then ran 'kmutil inspect | grep -i magewell' and the references to the old kexts came back again We have indeed identified a solution to address this issue: kmutil trigger-panic-medic --volume-root /Volumes/<YourVolumeName> However, this method requires booting into Recovery Mode, which is unacceptable for many of our customers. Especially for those who need bulk remote management, having personnel physically operate each machine one by one is simply not feasible. Therefore, is there a method to completely uninstall the kext driver while in normal mode? Thank you!

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!

We have developed the driver for the ProCapture video capture card based on PCIDriverKit. The App can communicate with the driver through the UserClient API. Currently, there is an issue where, when the App starts, there is a small probability that it causes a driver crash. However, the crash stack trace does not point to our code but appears to be within the PCIDriverKit framework. We have spent several weeks debugging but still cannot identify the root cause of the crash. Could you please review the crash log and suggest any methods to help pinpoint the issue? com.magewell.ProCaptureDriver-2025-09-15-153522.ips com.magewell.ProCaptureDriver-2025-09-15-082500.ips