/sys/class/drm/renderD*/device/device is Linux-only, so use a BSD extension
to get vendor/device identifiers from rendor nodes. Based on libdrm code.

$ ffmpeg -hide_banner -init_hw_device qsv=auto -i foo.y4m -vf hwupload=extra_hw_frames=64,format=qsv -c:v h264_qsv -y foo.mkv
[AVHWDeviceContext @ 0x8062d0140] Error initializing an MFX session: -3.
Device creation failed: -1313558101.
Failed to set value 'qsv=auto' for option 'init_hw_device': Unknown error occurred
Error parsing global options: Unknown error occurred

--- dispatcher/linux/device_ids.h.orig	2021-12-17 04:19:18 UTC
+++ dispatcher/linux/device_ids.h
@@ -377,7 +377,62 @@ static inline eMFXHWType get_platform(unsigned int dev
     return MFX_HW_UNKNOWN;
 }
 
+#if defined(__DragonFly__) || defined(__FreeBSD__) || defined(__OpenBSD__)
+#if defined(__FreeBSD__) && __FreeBSD__ < 13
+#include <sys/sysctl.h>
+#else
+#include <sys/ioctl.h>
+#include <fcntl.h>
+#include <unistd.h>
+#endif // defined(__FreeBSD__) && __FreeBSD__ < 13
+
+struct drm_pciinfo {
+	uint16_t	domain;
+	uint8_t		bus;
+	uint8_t		dev;
+	uint8_t		func;
+	uint16_t	vendor_id;
+	uint16_t	device_id;
+	uint16_t	subvendor_id;
+	uint16_t	subdevice_id;
+	uint8_t		revision_id;
+};
+
+#define DRM_IOCTL_BASE		'd'
+#define DRM_IOR(nr,type)	_IOR(DRM_IOCTL_BASE,nr,type)
+#define DRM_IOCTL_GET_PCIINFO	DRM_IOR(0x15, struct drm_pciinfo)
+#endif
+
 static mfxStatus get_devices(std::vector<Device> &allDevices) {
+#ifdef DRM_IOCTL_GET_PCIINFO
+    std::vector <Device> result;
+    for (int i = 0; i < 64; ++i) {
+#if defined(__FreeBSD__) && __FreeBSD__ < 13
+        std::string mib = "dev.drm." + std::to_string(128 + i) + ".PCI_ID";
+        char pci_id[20];
+        size_t len = sizeof(pci_id);
+        if (sysctlbyname(mib.c_str(), pci_id, &len, NULL, 0)) continue;
+        Device device;
+        sscanf(pci_id, "%x:%x", &device.vendor_id, &device.device_id);
+#else
+        std::string path = "/dev/dri/renderD" + std::to_string(128 + i);
+        int fd = open(path.c_str(), O_RDONLY);
+        if (fd == -1) continue;
+        struct drm_pciinfo pinfo;
+        if (ioctl(fd, DRM_IOCTL_GET_PCIINFO, &pinfo)) {
+            close(fd);
+            continue;
+        }
+        Device device = { .vendor_id = pinfo.vendor_id, .device_id = pinfo.device_id };
+        close(fd);
+#endif // defined(__FreeBSD__) && __FreeBSD__ < 13
+        if (device.vendor_id != 0x8086) {  // Filter out non-Intel devices
+            continue;
+        }
+        device.platform = get_platform(device.device_id);
+        allDevices.emplace_back(device);
+    }
+#else
     const char *dir            = "/sys/class/drm";
     const char *device_id_file = "/device/device";
     const char *vendor_id_file = "/device/vendor";
@@ -413,6 +468,7 @@ static mfxStatus get_devices(std::vector<Device> &allD
 
         allDevices.emplace_back(device);
     }
+#endif
 
     // sort by platform, unknown will appear at beginning
     std::sort(allDevices.begin(), allDevices.end(), [](const Device &a, const Device &b) {
--- dispatcher/vpl/mfx_dispatcher_vpl_msdk.cpp.orig	2022-03-04 22:06:17 UTC
+++ dispatcher/vpl/mfx_dispatcher_vpl_msdk.cpp
@@ -446,6 +446,32 @@ mfxStatus LoaderCtxMSDK::CheckD3D9Support(mfxU64 luid,
 #endif
 }
 
+#if defined(__DragonFly__) || defined(__FreeBSD__) || defined(__OpenBSD__)
+#if defined(__FreeBSD__) && __FreeBSD__ < 13
+#include <sys/sysctl.h>
+#else
+#include <sys/ioctl.h>
+#include <fcntl.h>
+#include <unistd.h>
+#endif // defined(__FreeBSD__) && __FreeBSD__ < 13
+
+struct drm_pciinfo {
+	uint16_t	domain;
+	uint8_t		bus;
+	uint8_t		dev;
+	uint8_t		func;
+	uint16_t	vendor_id;
+	uint16_t	device_id;
+	uint16_t	subvendor_id;
+	uint16_t	subdevice_id;
+	uint8_t		revision_id;
+};
+
+#define DRM_IOCTL_BASE		'd'
+#define DRM_IOR(nr,type)	_IOR(DRM_IOCTL_BASE,nr,type)
+#define DRM_IOCTL_GET_PCIINFO	DRM_IOR(0x15, struct drm_pciinfo)
+#endif
+
 mfxStatus LoaderCtxMSDK::GetRenderNodeDescription(mfxU32 adapterID,
                                                   mfxU32 &vendorID,
                                                   mfxU16 &deviceID) {
@@ -456,6 +482,28 @@
     mfxU32 DRMRenderNodeNum = 128 + adapterID;
     std::string nodeStr     = std::to_string(DRMRenderNodeNum);
 
+#ifdef DRM_IOCTL_GET_PCIINFO
+#if defined(__FreeBSD__) && __FreeBSD__ < 13
+    std::string mib = "dev.drm." + nodeStr + ".PCI_ID";
+    char pci_id[20];
+    size_t len = sizeof(pci_id);
+    if (!sysctlbyname(mib.c_str(), pci_id, &len, NULL, 0))
+        sscanf(pci_id, "%x:%hx", &vendorID, &deviceID);
+#else
+    std::string path = "/dev/dri/renderD" + nodeStr;
+    int fd = open(path.c_str(), O_RDONLY);
+    if (fd != -1) {
+        struct drm_pciinfo pinfo;
+        if (!ioctl(fd, DRM_IOCTL_GET_PCIINFO, &pinfo)) {
+            vendorID = pinfo.vendor_id;
+            deviceID = pinfo.device_id;
+        }
+        close(fd);
+    }
+#endif // defined(__FreeBSD__) && __FreeBSD__ < 13
+    if (vendorID != 0x8086)
+        return MFX_ERR_UNSUPPORTED;
+#else
     std::string vendorPath = "/sys/class/drm/renderD" + nodeStr + "/device/vendor";
     std::string devPath    = "/sys/class/drm/renderD" + nodeStr + "/device/device";
 
@@ -481,6 +529,7 @@ mfxStatus LoaderCtxMSDK::GetRenderNodeDescription(mfxU
             deviceID = (mfxU32)u32;
         fclose(devFile);
     }
+#endif
 
     if (deviceID == 0)
         return MFX_ERR_UNSUPPORTED;