text: #include <stdio.h>
  #include <stdint.h>
  #include <fcntl.h>
  #include <sys/mman.h>
  #include <sys/ioctl.h>
  #include <drm/drm.h>
  #include <drm/drm_mode.h>
  
  int main()
  {
  //------------------------------------------------------------------------------
  //Opening the DRI device
  //------------------------------------------------------------------------------
  
  	int dri_fd  = open("/dev/dri/card0",O_RDWR | O_CLOEXEC);
  
  //------------------------------------------------------------------------------
  //Kernel Mode Setting (KMS)
  //------------------------------------------------------------------------------
  
  	uint64_t res_fb_buf[10]={0},
  			res_crtc_buf[10]={0},
  			res_conn_buf[10]={0},
  			res_enc_buf[10]={0};
  
  	struct drm_mode_card_res res={0};
  
  	//Become the "master" of the DRI device
  	ioctl(dri_fd, DRM_IOCTL_SET_MASTER, 0);
  
  	//Get resource counts
  	ioctl(dri_fd, DRM_IOCTL_MODE_GETRESOURCES, &res);
  	res.fb_id_ptr=(uint64_t)res_fb_buf;
  	res.crtc_id_ptr=(uint64_t)res_crtc_buf;
  	res.connector_id_ptr=(uint64_t)res_conn_buf;
  	res.encoder_id_ptr=(uint64_t)res_enc_buf;
  	//Get resource IDs
  	ioctl(dri_fd, DRM_IOCTL_MODE_GETRESOURCES, &res);
  
  	printf("fb: %d, crtc: %d, conn: %d, enc: %d\n",res.count_fbs,res.count_crtcs,res.count_connectors,res.count_encoders);
  
  	void *fb_base[10];
  	long fb_w[10];
  	long fb_h[10];
  
  	//Loop though all available connectors
  	int i;
  	for (i=0;i<res.count_connectors;i++)
  	{
  		struct drm_mode_modeinfo conn_mode_buf[20]={0};
  		uint64_t	conn_prop_buf[20]={0},
  					conn_propval_buf[20]={0},
  					conn_enc_buf[20]={0};
  
  		struct drm_mode_get_connector conn={0};
  
  		conn.connector_id=res_conn_buf[i];
  
  		ioctl(dri_fd, DRM_IOCTL_MODE_GETCONNECTOR, &conn);	//get connector resource counts
  		conn.modes_ptr=(uint64_t)conn_mode_buf;
  		conn.props_ptr=(uint64_t)conn_prop_buf;
  		conn.prop_values_ptr=(uint64_t)conn_propval_buf;
  		conn.encoders_ptr=(uint64_t)conn_enc_buf;
  		ioctl(dri_fd, DRM_IOCTL_MODE_GETCONNECTOR, &conn);	//get connector resources
  
  		//Check if the connector is OK to use (connected to something)
  		if (conn.count_encoders<1 || conn.count_modes<1 || !conn.encoder_id || !conn.connection)
  		{
  			printf("Not connected\n");
  			continue;
  		}
  
  //------------------------------------------------------------------------------
  //Creating a dumb buffer
  //------------------------------------------------------------------------------
  		struct drm_mode_create_dumb create_dumb={0};
  		struct drm_mode_map_dumb map_dumb={0};
  		struct drm_mode_fb_cmd cmd_dumb={0};
  
  		//If we create the buffer later, we can get the size of the screen first.
  		//This must be a valid mode, so it's probably best to do this after we find
  		//a valid crtc with modes.
  		create_dumb.width = conn_mode_buf[0].hdisplay;
  		create_dumb.height = conn_mode_buf[0].vdisplay;
  		create_dumb.bpp = 32;
  		create_dumb.flags = 0;
  		create_dumb.pitch = 0;
  		create_dumb.size = 0;
  		create_dumb.handle = 0;
  		ioctl(dri_fd, DRM_IOCTL_MODE_CREATE_DUMB, &create_dumb);
  
  		cmd_dumb.width=create_dumb.width;
  		cmd_dumb.height=create_dumb.height;
  		cmd_dumb.bpp=create_dumb.bpp;
  		cmd_dumb.pitch=create_dumb.pitch;
  		cmd_dumb.depth=24;
  		cmd_dumb.handle=create_dumb.handle;
  		ioctl(dri_fd,DRM_IOCTL_MODE_ADDFB,&cmd_dumb);
  
  		map_dumb.handle=create_dumb.handle;
  		ioctl(dri_fd,DRM_IOCTL_MODE_MAP_DUMB,&map_dumb);
  
  		fb_base[i] = mmap(0, create_dumb.size, PROT_READ | PROT_WRITE, MAP_SHARED, dri_fd, map_dumb.offset);
  		fb_w[i]=create_dumb.width;
  		fb_h[i]=create_dumb.height;
  
  //------------------------------------------------------------------------------
  //Kernel Mode Setting (KMS)
  //------------------------------------------------------------------------------
  
  		printf("%d : mode: %d, prop: %d, enc: %d\n",conn.connection,conn.count_modes,conn.count_props,conn.count_encoders);
  		printf("modes: %dx%d FB: %d\n",conn_mode_buf[0].hdisplay,conn_mode_buf[0].vdisplay,fb_base[i]);
  
  		struct drm_mode_get_encoder enc={0};
  
  		enc.encoder_id=conn.encoder_id;
  		ioctl(dri_fd, DRM_IOCTL_MODE_GETENCODER, &enc);	//get encoder
  
  		struct drm_mode_crtc crtc={0};
  
  		crtc.crtc_id=enc.crtc_id;
  		ioctl(dri_fd, DRM_IOCTL_MODE_GETCRTC, &crtc);
  
  		crtc.fb_id=cmd_dumb.fb_id;
  		crtc.set_connectors_ptr=(uint64_t)&res_conn_buf[i];
  		crtc.count_connectors=1;
  		crtc.mode=conn_mode_buf[0];
  		crtc.mode_valid=1;
  		ioctl(dri_fd, DRM_IOCTL_MODE_SETCRTC, &crtc);
  	}
  
  	//Stop being the "master" of the DRI device
  	ioctl(dri_fd, DRM_IOCTL_DROP_MASTER, 0);
  
  	int x,y;
  	for (i=0;i<100;i++)
  	{
  		int j;
  		for (j=0;j<res.count_connectors;j++)
  		{
  			int col=(rand()%0x00ffffff)&0x00ff00ff;
  			for (y=0;y<fb_h[j];y++)
  				for (x=0;x<fb_w[j];x++)
  				{
  					int location=y*(fb_w[j]) + x;
  					*(((uint32_t*)fb_base[j])+location)=col;
  				}
  		}
  		usleep(100000);
  	}
  
  	return 0;
  }