RedBear-OS/local/patches/libdrm/02-redox-dispatch.patch

diff --git a/xf86drm.c b/xf86drm.c
index 3a10589..207c456 100644
--- a/xf86drm.c
+++ b/xf86drm.c
@@ -88,8 +88,10 @@
 #endif
 
 #include "xf86drm.h"
+#include "xf86drm_redox.h"
 #include "libdrm_macros.h"
 #include "drm_fourcc.h"
+#include "virtgpu_drm.h"
 
 #include "util_math.h"
 
@@ -113,7 +115,7 @@
 #define DRM_MAJOR 226 /* Linux */
 #endif
 
-#if defined(__OpenBSD__) || defined(__DragonFly__)
+#if defined(__OpenBSD__) || defined(__DragonFly__) || defined(__redox__)
 struct drm_pciinfo {
 	uint16_t	domain;
 	uint8_t		bus;
@@ -313,7 +315,6 @@ drmGetFormatModifierNameFromArm(uint64_t modifier)
     uint64_t type = (modifier >> 52) & 0xf;
 
     FILE *fp;
-    size_t size = 0;
     char *modifier_name = NULL;
     bool result = false;
 
@@ -321,6 +322,7 @@ drmGetFormatModifierNameFromArm(uint64_t modifier)
     fprintf(stderr, "open_memstream not available on Redox\n");
     return NULL;
 #else
+    size_t size = 0;
     fp = open_memstream(&modifier_name, &size);
     if (!fp)
         return NULL;
@@ -425,12 +427,12 @@ drmGetFormatModifierNameFromAmd(uint64_t modifier)
     uint64_t tile_version = AMD_FMT_MOD_GET(TILE_VERSION, modifier);
     FILE *fp;
     char *mod_amd = NULL;
-    size_t size = 0;
 
 #if defined(__redox__)
     fprintf(stderr, "open_memstream not available on Redox\n");
     return NULL;
 #else
+    size_t size = 0;
     fp = open_memstream(&mod_amd, &size);
     if (!fp)
         return NULL;
@@ -703,18 +705,366 @@ drm_public void drmFree(void *pt)
     free(pt);
 }
 
+#if defined(__redox__)
+static int redox_drm_write_all(int fd, const void *buf, size_t len)
+{
+	const uint8_t *bytes = buf;
+	size_t offset = 0;
+
+	while (offset < len) {
+		ssize_t written = write(fd, bytes + offset, len - offset);
+		if (written < 0) {
+			if (errno == EINTR || errno == EAGAIN)
+				continue;
+			return -1;
+		}
+		if (written == 0) {
+			errno = EIO;
+			return -1;
+		}
+		offset += (size_t)written;
+	}
+
+	return 0;
+}
+
+static int redox_drm_read_all(int fd, void *buf, size_t len)
+{
+	uint8_t *bytes = buf;
+	size_t offset = 0;
+
+	while (offset < len) {
+		ssize_t read_count = read(fd, bytes + offset, len - offset);
+		if (read_count < 0) {
+			if (errno == EINTR || errno == EAGAIN)
+				continue;
+			return -1;
+		}
+		if (read_count == 0) {
+			errno = EIO;
+			return -1;
+		}
+		offset += (size_t)read_count;
+	}
+
+	return 0;
+}
+
+static int redox_drm_send_request(int fd, unsigned long request_code,
+				  const void *payload, size_t payload_size)
+{
+	const size_t request_word_size = sizeof(uintptr_t);
+	const size_t total_size = request_word_size + payload_size;
+	uint8_t stack_request[sizeof(uintptr_t)];
+	uint8_t *request_bytes = stack_request;
+	uintptr_t request_word = (uintptr_t)request_code;
+	size_t i;
+
+	if (total_size > sizeof(stack_request)) {
+		request_bytes = drmMalloc(total_size);
+		if (!request_bytes) {
+			errno = ENOMEM;
+			return -1;
+		}
+	}
+
+	for (i = 0; i < request_word_size; ++i)
+		request_bytes[i] = (uint8_t)((request_word >> (i * 8)) & 0xffU);
+
+	if (payload_size != 0)
+		memcpy(request_bytes + request_word_size, payload, payload_size);
+
+	if (redox_drm_write_all(fd, request_bytes, total_size) != 0) {
+		if (request_bytes != stack_request)
+			drmFree(request_bytes);
+		return -1;
+	}
+
+	if (request_bytes != stack_request)
+		drmFree(request_bytes);
+
+	return 0;
+}
+
+static int redox_drm_get_response_size(int fd, size_t *response_size)
+{
+	stat_t st;
+
+	if (fstat(fd, &st) != 0)
+		return -1;
+
+	*response_size = (size_t)st.st_size;
+	return 0;
+}
+
+unsigned long redox_translate_request(unsigned long linux_nr)
+{
+	switch (linux_nr) {
+	case 0x0C:
+		return REDOX_DRM_IOCTL_GET_CAP;
+	case 0x0D:
+		return REDOX_DRM_IOCTL_SET_CLIENT_CAP;
+	case 0x09:
+		return REDOX_DRM_IOCTL_GEM_CLOSE;
+	case 0xA6:
+		return REDOX_DRM_IOCTL_MODE_GETENCODER;
+	case 0xB3:
+		return REDOX_DRM_IOCTL_MODE_MAP_DUMB;
+	case 0xB4:
+		return REDOX_DRM_IOCTL_MODE_DESTROY_DUMB;
+	case 0xAF:
+		return REDOX_DRM_IOCTL_MODE_RMFB;
+	/* VirtGPU ioctls (NR 0x41-0x4B) */
+	case 0x41:
+		return REDOX_DRM_IOCTL_VIRTGPU_MAP;
+	case 0x42:
+		return REDOX_DRM_IOCTL_VIRTGPU_EXECBUFFER;
+	case 0x43:
+		return REDOX_DRM_IOCTL_VIRTGPU_GETPARAM;
+	case 0x44:
+		return REDOX_DRM_IOCTL_VIRTGPU_RESOURCE_CREATE;
+	case 0x45:
+		return REDOX_DRM_IOCTL_VIRTGPU_RESOURCE_INFO;
+	case 0x46:
+		return REDOX_DRM_IOCTL_VIRTGPU_TRANSFER_FROM_HOST;
+	case 0x47:
+		return REDOX_DRM_IOCTL_VIRTGPU_TRANSFER_TO_HOST;
+	case 0x48:
+		return REDOX_DRM_IOCTL_VIRTGPU_WAIT;
+	case 0x49:
+		return REDOX_DRM_IOCTL_VIRTGPU_GET_CAPS;
+	case 0x4A:
+		return REDOX_DRM_IOCTL_VIRTGPU_RESOURCE_CREATE_BLOB;
+	case 0x4B:
+		return REDOX_DRM_IOCTL_VIRTGPU_CONTEXT_INIT;
+	/* Additional standard DRM ioctls */
+	case 0x00:
+		return REDOX_DRM_IOCTL_VERSION;
+	case 0xA0:
+		return REDOX_DRM_IOCTL_MODE_GETRESOURCES;
+	case 0xA1:
+		return REDOX_DRM_IOCTL_MODE_GETCRTC;
+	case 0xA2:
+		return REDOX_DRM_IOCTL_MODE_SETCRTC;
+	case 0xA3:
+		return REDOX_DRM_IOCTL_MODE_GETCONNECTOR;
+	case 0xA4:
+		return REDOX_DRM_IOCTL_MODE_PAGE_FLIP;
+	case 0xA8:
+		return REDOX_DRM_IOCTL_MODE_CREATE_DUMB;
+	case 0xAC:
+		return REDOX_DRM_IOCTL_MODE_ADDFB;
+	case 0x2B:
+		return REDOX_DRM_IOCTL_PRIME_HANDLE_TO_FD;
+	case 0x2C:
+		return REDOX_DRM_IOCTL_PRIME_FD_TO_HANDLE;
+	/* DRM_IOCTL_GET_PCIINFO — PCI device information for driver discovery */
+	case 0x15:
+		return REDOX_DRM_IOCTL_GET_PCI_INFO;
+	/* DRM auth/master ioctls */
+	case 0x02:  /* GET_MAGIC  — DRM_IOR(0x02, struct drm_auth) */
+		return REDOX_DRM_IOCTL_GET_MAGIC;
+	case 0x11:  /* AUTH_MAGIC — DRM_IOW(0x11, struct drm_auth) */
+		return REDOX_DRM_IOCTL_AUTH_MAGIC;
+	case 0x1e:  /* SET_MASTER — DRM_IO(0x1e) */
+		return REDOX_DRM_IOCTL_SET_MASTER;
+	case 0x1f:  /* DROP_MASTER — DRM_IO(0x1f) */
+		return REDOX_DRM_IOCTL_DROP_MASTER;
+	default:
+		return 0;
+	}
+}
+
+int redox_drm_exchange(int fd, unsigned long request_code,
+		       const void *payload, size_t payload_size,
+		       void *response, size_t response_capacity,
+		       size_t *response_size)
+{
+	uint8_t stack_buffer[64];
+	uint8_t *response_buffer = stack_buffer;
+	size_t actual_response_size = 0;
+
+	if (redox_drm_send_request(fd, request_code, payload, payload_size) != 0)
+		return -1;
+
+	if (redox_drm_get_response_size(fd, &actual_response_size) != 0)
+		return -1;
+
+	if (response_size)
+		*response_size = actual_response_size;
+
+	if (actual_response_size == 0)
+		return 0;
+
+	if (response && response_capacity >= actual_response_size) {
+		return redox_drm_read_all(fd, response, actual_response_size);
+	}
+
+	if (actual_response_size > sizeof(stack_buffer)) {
+		response_buffer = drmMalloc(actual_response_size);
+		if (!response_buffer) {
+			errno = ENOMEM;
+			return -1;
+		}
+	}
+
+	if (redox_drm_read_all(fd, response_buffer, actual_response_size) != 0) {
+		if (response_buffer != stack_buffer)
+			drmFree(response_buffer);
+		return -1;
+	}
+
+	if (response_buffer != stack_buffer)
+		drmFree(response_buffer);
+
+	if (response && response_capacity < actual_response_size) {
+		errno = EMSGSIZE;
+		return -1;
+	}
+
+	return 0;
+}
+
+int redox_drm_exchange_alloc(int fd, unsigned long request_code,
+			     const void *payload, size_t payload_size,
+			     void **response, size_t *response_size)
+{
+	size_t actual_response_size = 0;
+	void *allocated_response = NULL;
+
+	if (!response) {
+		errno = EINVAL;
+		return -1;
+	}
+
+	if (redox_drm_send_request(fd, request_code, payload, payload_size) != 0)
+		return -1;
+
+	if (redox_drm_get_response_size(fd, &actual_response_size) != 0)
+		return -1;
+
+	if (actual_response_size != 0) {
+		allocated_response = drmMalloc(actual_response_size);
+		if (!allocated_response) {
+			errno = ENOMEM;
+			return -1;
+		}
+
+		if (redox_drm_read_all(fd, allocated_response, actual_response_size) != 0) {
+			drmFree(allocated_response);
+			return -1;
+		}
+	}
+
+	*response = allocated_response;
+	if (response_size)
+		*response_size = actual_response_size;
+	return 0;
+}
+
+static size_t redox_drm_expected_response_size(unsigned long linux_nr, size_t arg_size)
+{
+	switch (linux_nr) {
+	case 0x00:  /* VERSION */
+	case 0x0C:
+	case 0x2B:  /* PRIME_HANDLE_TO_FD */
+	case 0x2C:  /* PRIME_FD_TO_HANDLE */
+	case 0x41:  /* VIRTGPU_MAP */
+	case 0x43:  /* VIRTGPU_GETPARAM */
+	case 0x44:  /* VIRTGPU_RESOURCE_CREATE */
+	case 0x45:  /* VIRTGPU_RESOURCE_INFO */
+	case 0xA0:  /* MODE_GETRESOURCES */
+	case 0xA1:  /* MODE_GETCRTC */
+	case 0xA3:  /* MODE_GETCONNECTOR */
+	case 0xA8:  /* MODE_CREATE_DUMB */
+	case 0xAC:  /* MODE_ADDFB */
+	case 0xA6:
+	case 0xB3:
+		return arg_size;
+	case 0x02:  /* GET_MAGIC — returns struct drm_auth (magic u32) */
+		return arg_size;
+	case 0x11:  /* AUTH_MAGIC — returns struct drm_auth (magic u32) */
+		return arg_size;
+	default:
+		return 0;
+	}
+}
+
+int redox_drm_simple_ioctl(int fd, unsigned long request, void *arg)
+{
+	const unsigned long linux_nr = REDOX_LINUX_IOCTL_NR(request);
+	const unsigned long request_code = redox_translate_request(linux_nr);
+	const size_t arg_size = REDOX_LINUX_IOCTL_SIZE(request);
+	const size_t expected_response_size = redox_drm_expected_response_size(linux_nr, arg_size);
+
+	if (request_code == 0) {
+		errno = ENOTTY;
+		return -1;
+	}
+
+	if (linux_nr == 0x42) { /* VIRTGPU_EXECBUFFER */
+		struct drm_virtgpu_execbuffer *eb = arg;
+		size_t total = arg_size + eb->size;
+		uint8_t *buf = drmMalloc((int)total);
+		int ret;
+
+		if (!buf)
+			return -1;
+
+		memcpy(buf, arg, arg_size);
+		if (eb->size > 0 && eb->command)
+			memcpy(buf + arg_size, (void *)(uintptr_t)eb->command, eb->size);
+
+		ret = redox_drm_exchange(fd, request_code, buf, total, NULL, 0, NULL);
+		drmFree(buf);
+		return ret;
+	}
+
+	if (linux_nr == 0x49) { /* VIRTGPU_GET_CAPS */
+		struct drm_virtgpu_get_caps *gc = arg;
+		void *resp;
+		size_t resp_size;
+		int ret;
+
+		ret = redox_drm_exchange_alloc(fd, request_code, arg, arg_size, &resp, &resp_size);
+		if (ret == 0 && resp && resp_size > 0) {
+			size_t copy = resp_size < gc->size ? resp_size : gc->size;
+
+			memcpy((void *)(uintptr_t)gc->addr, resp, copy);
+			drmFree(resp);
+		}
+
+		return ret;
+	}
+
+	if (redox_drm_exchange(fd, request_code,
+			       arg, arg ? arg_size : 0,
+			       expected_response_size ? arg : NULL,
+			       expected_response_size,
+			       NULL) != 0) {
+		return -1;
+	}
+
+	return 0;
+}
+#endif
+
 /**
  * Call ioctl, restarting if it is interrupted
  */
 drm_public int
 drmIoctl(int fd, unsigned long request, void *arg)
 {
+	#if defined(__redox__)
+	return redox_drm_simple_ioctl(fd, request, arg);
+	#else
     int ret;
 
     do {
         ret = ioctl(fd, request, arg);
     } while (ret == -1 && (errno == EINTR || errno == EAGAIN));
     return ret;
+	#endif
 }
 
 static unsigned long drmGetKeyFromFd(int fd)
@@ -1093,6 +1443,7 @@ static int drmGetMinorType(int major, int minor)
     return -1;
 }
 
+#if !defined(__redox__)
 static const char *drmGetMinorName(int type)
 {
     switch (type) {
@@ -1104,6 +1455,7 @@ static const char *drmGetMinorName(int type)
         return NULL;
     }
 }
+#endif
 
 /**
  * Open the device by bus ID.
@@ -1201,7 +1553,11 @@ static int drmOpenByName(const char *name, int type)
     for (i = base; i < base + DRM_MAX_MINOR; i++) {
         if ((fd = drmOpenMinor(i, 1, type)) >= 0) {
             if ((version = drmGetVersion(fd))) {
+                #if defined(__redox__)
+                if (!version->name || !strcmp(version->name, name)) {
+                #else
                 if (!strcmp(version->name, name)) {
+                #endif
                     drmFreeVersion(version);
                     id = drmGetBusid(fd);
                     drmMsg("drmGetBusid returned '%s'\n", id ? id : "NULL");
@@ -1354,6 +1710,7 @@ drm_public void drmFreeVersion(drmVersionPtr v)
  * Used by drmGetVersion() to free the memory pointed by \p %v as well as all
  * the non-null strings pointers in it.
  */
+#if !defined(__redox__)
 static void drmFreeKernelVersion(drm_version_t *v)
 {
     if (!v)
@@ -1363,6 +1720,7 @@ static void drmFreeKernelVersion(drm_version_t *v)
     drmFree(v->desc);
     drmFree(v);
 }
+#endif
 
 
 /**
@@ -1375,6 +1733,7 @@ static void drmFreeKernelVersion(drm_version_t *v)
  * Used by drmGetVersion() to translate the information returned by the ioctl
  * interface in a private structure into the public structure counterpart.
  */
+#if !defined(__redox__)
 static void drmCopyVersion(drmVersionPtr d, const drm_version_t *s)
 {
     d->version_major      = s->version_major;
@@ -1387,6 +1746,7 @@ static void drmCopyVersion(drmVersionPtr d, const drm_version_t *s)
     d->desc_len           = s->desc_len;
     d->desc               = s->desc ? strdup(s->desc) : NULL;
 }
+#endif
 
 
 /**
@@ -1406,6 +1766,50 @@ static void drmCopyVersion(drmVersionPtr d, const drm_version_t *s)
  */
 drm_public drmVersionPtr drmGetVersion(int fd)
 {
+	#if defined(__redox__)
+	drmVersionPtr retval = drmMalloc(sizeof(*retval));
+	struct redox_drm_version_wire version;
+
+	if (!retval)
+		return NULL;
+
+	if (redox_drm_exchange(fd, REDOX_DRM_IOCTL_VERSION,
+			       NULL, 0,
+			       &version, sizeof(version),
+			       NULL) != 0) {
+		drmFree(retval);
+		return NULL;
+	}
+
+	memclear(*retval);
+	retval->version_major = version.major;
+	retval->version_minor = version.minor;
+	retval->version_patchlevel = version.patch;
+
+	/* The scheme returns a NUL-terminated driver name in version.name.
+	 * KWin drm_gpu.cpp dereferences version->name unconditionally
+	 * (strstr checks for "i915", "amdgpu", "virtio" etc.) so it must
+	 * never be NULL.
+	 */
+	version.name[sizeof(version.name) - 1] = '\0';
+	if (version.name[0] != '\0') {
+		size_t len = strlen(version.name);
+		retval->name = drmMalloc(len + 1);
+		if (retval->name) {
+			memcpy(retval->name, version.name, len + 1);
+			retval->name_len = len;
+		}
+	} else {
+		const char fallback[] = "redox-drm";
+		retval->name = drmMalloc(sizeof(fallback));
+		if (retval->name) {
+			memcpy(retval->name, fallback, sizeof(fallback));
+			retval->name_len = sizeof(fallback) - 1;
+		}
+	}
+
+	return retval;
+	#else
     drmVersionPtr retval;
     drm_version_t *version = drmMalloc(sizeof(*version));
 
@@ -1436,6 +1840,7 @@ drm_public drmVersionPtr drmGetVersion(int fd)
     drmCopyVersion(retval, version);
     drmFreeKernelVersion(version);
     return retval;
+	#endif
 }
 
 
@@ -3400,6 +3805,23 @@ drm_public int drmGetNodeTypeFromFd(int fd)
 drm_public int drmPrimeHandleToFD(int fd, uint32_t handle, uint32_t flags,
                                   int *prime_fd)
 {
+	#if defined(__redox__)
+	struct redox_drm_prime_handle_to_fd_wire request;
+	struct redox_drm_prime_handle_to_fd_response_wire response;
+
+	memclear(request);
+	request.handle = handle;
+	request.flags = flags;
+	if (redox_drm_exchange(fd, REDOX_DRM_IOCTL_PRIME_HANDLE_TO_FD,
+			       &request, sizeof(request),
+			       &response, sizeof(response),
+			       NULL) != 0) {
+		return -errno;
+	}
+
+	*prime_fd = response.fd;
+	return 0;
+	#else
     struct drm_prime_handle args;
     int ret;
 
@@ -3413,10 +3835,27 @@ drm_public int drmPrimeHandleToFD(int fd, uint32_t handle, uint32_t flags,
 
     *prime_fd = args.fd;
     return 0;
+	#endif
 }
 
 drm_public int drmPrimeFDToHandle(int fd, int prime_fd, uint32_t *handle)
 {
+	#if defined(__redox__)
+	struct redox_drm_prime_fd_to_handle_wire request;
+	struct redox_drm_prime_fd_to_handle_response_wire response;
+
+	memclear(request);
+	request.fd = prime_fd;
+	if (redox_drm_exchange(fd, REDOX_DRM_IOCTL_PRIME_FD_TO_HANDLE,
+			       &request, sizeof(request),
+			       &response, sizeof(response),
+			       NULL) != 0) {
+		return -errno;
+	}
+
+	*handle = response.handle;
+	return 0;
+	#else
     struct drm_prime_handle args;
     int ret;
 
@@ -3428,6 +3867,7 @@ drm_public int drmPrimeFDToHandle(int fd, int prime_fd, uint32_t *handle)
 
     *handle = args.handle;
     return 0;
+	#endif
 }
 
 drm_public int drmCloseBufferHandle(int fd, uint32_t handle)
@@ -3544,7 +3984,7 @@ static char *drmGetMinorNameForFD(int fd, int type)
     n = drmGetNodePath(buf, sizeof(buf), type, min);
     if (n < 0)
         return NULL;
-    if (n == -1 || n >= sizeof(buf))
+    if ((size_t)n >= sizeof(buf))
         return NULL;
 
     return strdup(buf);
@@ -3666,7 +4106,7 @@ static int drmParseSubsystemType(int maj, int min)
             return DRM_BUS_VIRTIO;
      }
     return subsystem_type;
-#elif defined(__OpenBSD__) || defined(__DragonFly__) || defined(__FreeBSD__)
+#elif defined(__OpenBSD__) || defined(__DragonFly__) || defined(__FreeBSD__) || defined(__redox__)
     return DRM_BUS_PCI;
 #else
 #warning "Missing implementation of drmParseSubsystemType"
@@ -3800,6 +4240,21 @@ static int drmParsePciBusInfo(int maj, int min, drmPciBusInfoPtr info)
     return 0;
 #elif defined(__FreeBSD__)
     return get_sysctl_pci_bus_info(maj, min, info);
+#elif defined(__redox__)
+    int rfd = open("/scheme/drm/card0", O_RDONLY);
+    if (rfd < 0)
+        return -errno;
+    uint8_t buf[22];
+    size_t rsize = 0;
+    int ret = redox_drm_exchange(rfd, REDOX_DRM_IOCTL_GET_PCI_INFO, NULL, 0, buf, sizeof(buf), &rsize);
+    close(rfd);
+    if (ret != 0 || rsize < 17)
+        return -EIO;
+    info->domain = buf[10] | (buf[11] << 8) | (buf[12] << 16) | (buf[13] << 24);
+    info->bus    = buf[14];
+    info->dev    = buf[15];
+    info->func   = buf[16];
+    return 0;
 #else
 #warning "Missing implementation of drmParsePciBusInfo"
     return -EINVAL;
@@ -4009,6 +4464,23 @@ static int drmParsePciDeviceInfo(int maj, int min,
     device->revision_id = results[0].pc_revid;
 
     return 0;
+#elif defined(__redox__)
+    int rfd2 = open("/scheme/drm/card0", O_RDONLY);
+    if (rfd2 < 0)
+        return -errno;
+    uint8_t dbuf[22];
+    size_t drsize = 0;
+    int dret = redox_drm_exchange(rfd2, REDOX_DRM_IOCTL_GET_PCI_INFO, NULL, 0, dbuf, sizeof(dbuf), &drsize);
+    close(rfd2);
+    if (dret != 0 || drsize < 9)
+        return -EIO;
+    device->vendor_id    = dbuf[0] | (dbuf[1] << 8);
+    device->device_id    = dbuf[2] | (dbuf[3] << 8);
+    device->subvendor_id = dbuf[4] | (dbuf[5] << 8);
+    device->subdevice_id = dbuf[6] | (dbuf[7] << 8);
+    if (drsize >= 9)
+        device->revision_id = dbuf[8];
+    return 0;
 #else
 #warning "Missing implementation of drmParsePciDeviceInfo"
     return -EINVAL;
@@ -4661,6 +5133,66 @@ drm_public int drmGetDeviceFromDevId(dev_t find_rdev, uint32_t flags, drmDeviceP
 
     *device = d;
 
+    return 0;
+#elif defined(__redox__)
+    /* On Redox there is no /dev/dri/ directory to enumerate.
+     * Instead, open /scheme/drm/card0 and query PCI info to
+     * construct a single drmDevice that serves as both primary
+     * and render node. */
+    drmDevicePtr devp;
+    char *pptr;
+    int max_node_length = 64, i;
+    size_t extra, psize;
+    uint8_t pbuf[22];
+    size_t prsize = 0;
+    int pret, fd;
+
+    if (device == NULL)
+        return -EINVAL;
+    if (drm_device_validate_flags(flags))
+        return -EINVAL;
+
+    fd = open("/scheme/drm/card0", O_RDWR | O_CLOEXEC);
+    if (fd < 0)
+        return -errno;
+
+    pret = redox_drm_exchange(fd, REDOX_DRM_IOCTL_GET_PCI_INFO, NULL, 0,
+                              pbuf, sizeof(pbuf), &prsize);
+    close(fd);
+    if (pret != 0 || prsize < 17)
+        return -EIO;
+
+    extra = DRM_NODE_MAX * (sizeof(void *) + max_node_length);
+    psize = sizeof(drmDevice) + extra + sizeof(drmPciBusInfo) + sizeof(drmPciDeviceInfo);
+    devp = calloc(1, psize);
+    if (!devp)
+        return -ENOMEM;
+
+    devp->bustype = DRM_BUS_PCI;
+    /* Advertise both PRIMARY and RENDER — same path on Redox */
+    devp->available_nodes = (1 << DRM_NODE_PRIMARY) | (1 << DRM_NODE_RENDER);
+    pptr = (char *)devp + sizeof(drmDevice);
+    devp->nodes = (char **)pptr;
+    pptr += DRM_NODE_MAX * sizeof(void *);
+    for (i = 0; i < DRM_NODE_MAX; i++) { devp->nodes[i] = pptr; pptr += max_node_length; }
+    snprintf(devp->nodes[DRM_NODE_PRIMARY], max_node_length, "/scheme/drm/card0");
+    snprintf(devp->nodes[DRM_NODE_RENDER], max_node_length, "/scheme/drm/card0");
+
+    devp->businfo.pci = (drmPciBusInfoPtr)pptr;
+    pptr += sizeof(drmPciBusInfo);
+    devp->businfo.pci->domain = pbuf[10] | (pbuf[11] << 8) | (pbuf[12] << 16) | (pbuf[13] << 24);
+    devp->businfo.pci->bus    = pbuf[14];
+    devp->businfo.pci->dev    = pbuf[15];
+    devp->businfo.pci->func   = pbuf[16];
+
+    devp->deviceinfo.pci = (drmPciDeviceInfoPtr)pptr;
+    devp->deviceinfo.pci->vendor_id    = pbuf[0] | (pbuf[1] << 8);
+    devp->deviceinfo.pci->device_id    = pbuf[2] | (pbuf[3] << 8);
+    devp->deviceinfo.pci->subvendor_id = pbuf[4] | (pbuf[5] << 8);
+    devp->deviceinfo.pci->subdevice_id = pbuf[6] | (pbuf[7] << 8);
+    devp->deviceinfo.pci->revision_id  = pbuf[8];
+
+    *device = devp;
     return 0;
 #else
     drmDevicePtr local_devices[MAX_DRM_NODES];
@@ -4761,6 +5293,66 @@ drm_public int drmGetNodeTypeFromDevId(dev_t devid)
  */
 drm_public int drmGetDevice2(int fd, uint32_t flags, drmDevicePtr *device)
 {
+#if defined(__redox__)
+    uint8_t pbuf[22];
+    size_t prsize = 0;
+    int pret;
+    uint16_t pvendor_id, pdevice_id, psubvendor_id, psubdevice_id, pdomain;
+    uint8_t prevision_id, pbus, pdev, pfunc;
+    const char *pnode;
+    int max_node_length, i;
+    size_t extra, psize;
+    drmDevicePtr devp;
+    char *pptr;
+
+    pret = redox_drm_exchange(fd, REDOX_DRM_IOCTL_GET_PCI_INFO, NULL, 0,
+                              pbuf, sizeof(pbuf), &prsize);
+    if (pret != 0 || prsize < 17)
+        return -EIO;
+
+    pvendor_id    = pbuf[0] | (pbuf[1] << 8);
+    pdevice_id    = pbuf[2] | (pbuf[3] << 8);
+    psubvendor_id = pbuf[4] | (pbuf[5] << 8);
+    psubdevice_id = pbuf[6] | (pbuf[7] << 8);
+    prevision_id  = pbuf[8];
+    pdomain       = pbuf[10] | (pbuf[11] << 8) | (pbuf[12] << 16) | (pbuf[13] << 24);
+    pbus          = pbuf[14];
+    pdev          = pbuf[15];
+    pfunc         = pbuf[16];
+
+    pnode = "/scheme/drm/card0";
+    max_node_length = 64;
+    extra = DRM_NODE_MAX * (sizeof(void *) + max_node_length);
+    psize = sizeof(drmDevice) + extra + sizeof(drmPciBusInfo) + sizeof(drmPciDeviceInfo);
+    devp = calloc(1, psize);
+    if (!devp)
+        return -ENOMEM;
+
+    devp->bustype = DRM_BUS_PCI;
+    devp->available_nodes = 1 << DRM_NODE_PRIMARY;
+    pptr = (char *)devp + sizeof(drmDevice);
+    devp->nodes = (char **)pptr;
+    pptr += DRM_NODE_MAX * sizeof(void *);
+    for (i = 0; i < DRM_NODE_MAX; i++) { devp->nodes[i] = pptr; pptr += max_node_length; }
+    snprintf(devp->nodes[DRM_NODE_PRIMARY], max_node_length, "%s", pnode);
+
+    devp->businfo.pci = (drmPciBusInfoPtr)pptr;
+    pptr += sizeof(drmPciBusInfo);
+    devp->businfo.pci->domain = pdomain;
+    devp->businfo.pci->bus = pbus;
+    devp->businfo.pci->dev = pdev;
+    devp->businfo.pci->func = pfunc;
+
+    devp->deviceinfo.pci = (drmPciDeviceInfoPtr)pptr;
+    devp->deviceinfo.pci->vendor_id = pvendor_id;
+    devp->deviceinfo.pci->device_id = pdevice_id;
+    devp->deviceinfo.pci->subvendor_id = psubvendor_id;
+    devp->deviceinfo.pci->subdevice_id = psubdevice_id;
+    devp->deviceinfo.pci->revision_id = prevision_id;
+
+    *device = devp;
+    return 0;
+#else
     struct stat sbuf;
 
     if (fd == -1)
@@ -4773,6 +5365,7 @@ drm_public int drmGetDevice2(int fd, uint32_t flags, drmDevicePtr *device)
         return -EINVAL;
 
     return drmGetDeviceFromDevId(sbuf.st_rdev, flags, device);
+#endif
 }
 
 /**