Information
This page has not been fully updated to reflect changes made in Toradex Linux BSP 6write a comment.
If you are using version 5 LTS, please visit theDocumentation for Version 5 LTS.
Danger
A lot of information about display times and resolution was previously discussed in this article. Content has been moved to a general article:Screen outputs, resolution and times.
Caution
This article is no longer maintained and is for reference only.
introduction
The framebuffer (fbdev) is a drawing device that provides access to graphics hardware. In addition to the frame buffer, there are other interfaces for accessing graphics hardware, such as the DRI (Direct Rendering Interface) or proprietary interfaces (NVIDIA driver). Frame buffering generally does not support 2D/3D hardware acceleration.
The i.MX 6 kernel ships with an open source fbdev driver called mxcfb. The X server controller is closed source and is called vivant.
The i.MX 7 and i.MX 6ULL kernels ship with an open source fbdev driver, mxsfb.
Our Tegra kernel comes with an open source fbdev driver called tegrafb. The X server driver, simply called tegra, is only available as a binary driver.
Vybrid kernels 4.1 and earlier ship with an fbdev driver called dcu. Kernels 4.4 and later ship with a DRM driver that supports the fbdev interface via fbdev emulation.
Framebuffer Console
By default, all modules use the kernel's internal fbdev-based console, which displays kernel and system log messages and virtual terminals. Because the kernel initializes the fbdev console at boot, it can be used to display a boot screen (rather than a console). Refer toSplash Screen (Linux)Article for detailed instructions.
Disable the framebuffer console
To disable on-screen console prompts, remove the kernel command line parameter "console=tty1" from the configuration environment variable in U-Boot. The content of the configuration is module specific, use print to see the initial content:
Print Hummingbird VFxx #
...
setup=setenv setupargs console=tty1 console=${console},${baudrate}n8 ${memargs} consoleblank=0
...
Colibri VFxx # setenv setup 'setenv setupargs console=${console},${baudrate}n8 ${memargs} consoleblank=0'
Hummingbird VFxx # save
Information
If you remove those tooconsole=Input to the Linux serial console returns to the framebuffer console. Use an invalid console (ex.Konsole = null) or remove kernel framebuffer console support (see below) to resolve this issue.
Here are some kernel arguments that can help disable the console, you should try a combination of them on your SoM:
- vt.global_cursor_default=0
- empty console = 0
- console=null oder console=${console}
- early
systemd still initializes a getty on tty1. This can easily be disabled with:
# systemctl desactivar getty@tty1.servicio
Remove the framebuffer console
To get rid of console messages and all system output, framebuffer console support can be completely removed from the kernel by removing the "CONFIG_FRAMEBUFFER_CONSOLE" kernel configuration.
Redirect framebuffer console
The fbcon environment variable can be used to specify the fbdev device used for the console. Use the following command to use fb1 as a console:
Colibri T20 # setenv Konfiguration "${configuration} fbcon=map:1"
To change the console after boot, one can use the con2fbmap tool, which can be easily created with OpenEmbedded. Change as follows:
# con2fbmap 1 1
For more information about the fbdev console, see the kernel documentation:
https://git.toradex.com/cgit/linux-toradex.git/tree/Documentation/fb/fbcon.txt?h=tegra
Tegra console edition
BSP v2.0 and later provide console via DVI-A/LVDS/RGB/VGA (LVDS-1 in X server terms) as standard and optional via DVI-D (HDMI-1 in X server terms). ). To enable the console framebuffer when booting to DVI-D instead of VGA, just set fbcon=map:1 in U-Boot like this:
Colibri T30 # setenv setup 'setenv setupargs asix_mac=${ethaddr} no_console_suspend=1 console=tty1 console=ttyS0,${baudrate}n8 debug_uartport=lsport,0 ${memargs} fbcon=map:1'
With the Apalis T30, we use the HDMI interface for the framebuffer console by default, since VGA is unfortunately not supported by the NVIDIA Tegra 3 SoC. To switch it back to Parallel RGB (e.g. when using an LVDS or Parallel RGB display), do the following:
Apalis T30 # setenv vidargs 'video=tegrafb0:800x480-16@60'
Apalis T30 # setenv setup 'setenv setupargs gpt gpt_sector=${gptoffset} igb_mac=${ethaddr} no_console_suspend=1 console=tty1 console=ttyS0,${baudrate}n8 debug_uartport=lsport,0 ${memargs} fbcon=map:0 '
console configuration
You can use the setterm utility (available in the util-linux package) to configure the framebuffer console.
Use:Some commands are only available in the framebuffer console itself (and not within an SSH session).
Energy saving settings such as Powersave and Blank could be of particular interest. With the blank parameter you can define the time until the console goes black (in minutes, 0 means never). With the power save command you can define the time until the framebuffer driver switches off the output completely (in minutes, after switching to blank mode, 0 means immediately after switching to blank mode).
set term -learn 1
setterm-powerdown 0
turn off setterm -powersave
There is also a kernel boot parameter to configure console wiping calledblank console(Suppression time in seconds, 0 means never). To turn off the blinking cursor, you can use thevt.global_cursor_defaultkernel parameters. Use the U-Boot console to set the boot parameter:
# setenv defargs consoleblank=0 vt.global_cursor_default=0
Example from Cairo
Cairo is a library providing primitives for drawing in two dimensions. This can be used to draw text and images onto a framebuffer device.
#contain <stdio.h>
#contain <stdlib.h>
#contain <string.h>
#contain <fcntl.h>
#contain <linux/tipos.h>
#contain <linux/ioctl.h>
#contain <linux/fb.h>
#contain <sys/mman.h>
#contain <kairo/kairo.h>
#contain <unistd.h>
#contain <sys/ioctl.h>
#define DELAY_IN_SECS 5
#define SCALE_WIDTH 256,0
#define HEIGHT_SCALE 256,0
Typdefinition Structure _cairo_linuxfb_device {
and tfb_fd;
char *data_fb;
Largofb_screen size;
Structure fb_var_screeninfofb_vinfo;
Structure fb_fix_screeninfofb_finfo;
}cairo_linuxfb_device_t;
/* Destroy a surface of Cairo */
file cairo_linuxfb_surface_destroy(file *Device)
{
cairo_linuxfb_device_t*developer= (cairo_linuxfb_device_t*)Device;
And (developer== NULL)
hand back;
world map(developer->data_fb,developer->fb_screen size);
Fence(developer->fb_fd);
frei(developer);
}
/* create Cairo area with given framebuffer */
cairo_surface_t*cairo_linuxfb_surface_create(Constantly char *fb_name)
{
cairo_linuxfb_device_t*Device;
cairo_surface_t*surface;
/* use fb0 if no framebuffer specified */
And (fb_name== NULL) {
fb_name= "/dev/fb0";
}
Device= malloc(size of(*Device));
And (!Device) {
Bad luck("Error: Unable to allocate memory\n");
Salida(1);
}
// Open file for reading and writing
Device->fb_fd= open(fb_name,O_RDWR);
And (Device->fb_fd== -1) {
Bad luck("Error: Cannot open device framebuffer");
becomeshandle_allocate_error;
}
// Get variable screen information
And (ioctl(Device->fb_fd,FBIOGET_VSCREENINFO, &Device->fb_vinfo) == -1) {
Bad luck("Error: Read variable information");
becomeshandle_ioctl_error;
}
// Find out the size of the screen in bytes
Device->fb_screen size=Device->fb_vinfo.xres*Device->fb_vinfo.Years
*Device->fb_vinfo.bits_por_pixel/ 8;
// Assign the device to storage
Device->data_fb= (char *)map mm(0,Device->fb_screen size,
PROT_LEER|PROT_WRITE,SHARED_MAP,
Device->fb_fd, 0);
And ((and t)Device->data_fb== -1) {
Bad luck("Error: Could not allocate device framebuffer to memory");
becomeshandle_ioctl_error;
}
// Get information about the still image
And (ioctl(Device->fb_fd,FBIOGET_FSCREENINFO, &Device->fb_finfo) == -1) {
Bad luck("Error reading pinned information");
becomeshandle_ioctl_error;
}
/* create Cairo surface to use for drawing */
surface= cairo_image_surface_create_for_data(Device->data_fb,
CAIRO_FORMAT_RGB16_565,
Device->fb_vinfo.xres,
Device->fb_vinfo.Years,
cairo_format_stride_for_width(CAIRO_FORMAT_RGB16_565,
Device->fb_vinfo.xres));
cairo_surface_set_user_data(surface, NULL,Device,
&cairo_linuxfb_surface_destroy);
hand backsurface;
handle_ioctl_error:
Fence(Device->fb_fd);
handle_allocate_error:
frei(Device);
Salida(1);
}
and t Headmaster(and tArgc, char *argv[]) {
and timage width;
and timage height;
charframe_buffer_number;
charfb_node[sixteen] = {0};
cairo_surface_t*surface;
cairo_surface_t*Bild;
Kairo_t*kr;
And (Argc!= 2) {
press("Usage: ./cairo /route/to/png/image\n");
Salida(1);
}
And (Callus(argv[1], ".png") == NULL) {
press("Only PNG images are supported in this example\n");
Salida(1);
}
press("Enter the image buffer number:\t");
Scan("%C", &frame_buffer_number);
run(fb_node, "/dev/fb");
fb_node[crash(fb_node)] =frame_buffer_number;
fb_node[crash(fb_node)] = '\0';
press("Framebuffer node is: %s\n",fb_node);
surface= cairo_linuxfb_surface_create(fb_node);
kr= cairo_create(surface);
/*
* We cleared the Cairo surface here before drawing
* This is necessary if something has been drawn on this area
* before, without this the previous content would not be deleted.
*/
elcairo_set_operator(kr,THE CAIRO_OPERATOR_CLEAR);
cairo_painting(kr);
elcairo_set_operator(kr,EL CAIRO_OPERATOR_OVER);
cairo_select_font_face(kr, "serife",CAIRO_FONT_SLANT_NORMAL,CAIRO_FONT_WEIGHT_BOLD);
cairo_set_font_size(kr, 32,0);
cairo_set_source_rgb(kr, 1.0, 1.0, 0,0);
cairo_move_to(kr, 100, 300);
elcairo_show_text(kr, "Example Toradex Cairo!");
/* Wait for the result of the draw operation to persist for the user to see */
sleep(DELAY_IN_SECS);
/* Clean up the surface and prepare it for a new drawing */
elcairo_set_operator(kr,THE CAIRO_OPERATOR_CLEAR);
cairo_painting(kr);
elcairo_set_operator(kr,EL CAIRO_OPERATOR_OVER);
Bild= cairo_image_surface_create_from_png(argv[1]);
image width= cairo_image_surface_get_width(Bild);
image height= cairo_image_surface_get_height(Bild);
/* scale image to any size */
cairo_scale(kr,SCALE_WIDTH/image width,HEIGHT_SCALE/image height);
cairo_set_source_surface(kr,Bild, 350, 200);
cairo_painting(kr);
/* Wait for the result of the draw operation to persist for the user to see */
sleep(DELAY_IN_SECS);
/* Destroy and free all contexts related to Cairo */
cairo_destroy(kr);
cairo_surface_destroy(surface);
hand back 0;
}
Below is the makefile that can be used to build the sample code abovedo Cairoprovided the SDK is configured as described inSDK for LinuxArticle.
Information
All command lines must begin with aeyelashinstead of spaces in a makefile.
SYSROOTS = /usr/local/oecore-x86_64/sysroots
CC = ${SYSROOTS}/x86_64-angströmsdk-linux/usr/bin/arm-angström-linux-gnueabi/arm-angström-linux-gnueabi-gcc
LIB_PATH = "-L${SYSROOTS}/armv7at2hf-neon-angström-linux-gnueabi/lib/"
POUNDS =-lcar
CFLAGS = -O2 -g -mfloat-abi=duro --sysroot=${SYSROOTS}/armv7at2hf-neon-angstrom-linux-gnueabi/
at:
${CC} ${CFLAGS} ${LIB_PATH} ${LIBS} ${INCLUDES} -o cairo cairo.c
sauber:
rm-rf el kairo
please refer toCairoDocumentation urehearse.
FAQs
How to enable framebuffer Linux? ›
The framebuffer console can be enabled by using your favorite kernel configuration tool. It is under Device Drivers->Graphics Support-> Console display driver support->Framebuffer Console Support. Select 'y' to compile support statically or 'm' for module support.
How does framebuffer work Linux? ›The frame buffer device provides an abstraction for the graphics hardware. It represents the frame buffer of some video hardware and allows application software to access the graphics hardware through a well-defined interface, so the software doesn't need to know anything about the low-level (hardware register) stuff.
How to disable framebuffer console in Linux kernel? ›To get rid of console messages and any system output, the framebuffer console support can be removed from the kernel entirely by removing the kernel configuration "CONFIG_FRAMEBUFFER_CONSOLE".
What is the frame buffer in computer graphics? ›A framebuffer (frame buffer, or sometimes framestore) is a portion of random-access memory (RAM) containing a bitmap that drives a video display. It is a memory buffer containing data representing all the pixels in a complete video frame.
How do I start XVFB on Linux? ›...
ps –ef | grep Xvfb
- Log in as the root user.
- Install the rpm package with the following command: [root@xxxx]# rpm -ivh packagename.rpm.
- Configure and start the server as described in the next section.
- Run the following command to modify the GRUB configuration file: Copy. sudo vi /boot/grub/grub.conf.
- Add following after the line containing timeout : Copy. serial --unit=0 --speed=115200 terminal --timeout=5 serial console.
- Append the following to each kernel line: Copy. console=tty1 console=ttyS0,115200.
The framebuffer console (fbcon), as its name implies, is a text console running on top of the framebuffer device. It has the functionality of any standard text console driver, such as the VGA console, with the added features that can be attributed to the graphical nature of the framebuffer.
What is EFI framebuffer? ݦ This is a generic EFI platform driver for systems with UEFI firmware. The system must be booted via the EFI stub for this to be usable. efifb supports both firmware with Graphics Output Protocol (GOP) displays as well as older systems with only Universal Graphics Adapter (UGA) displays.
What are Linux memory buffers? ›Buffer memory is a temporary storage area in the main memory (RAM) that stores data transferring between two or more devices or between an application and a device. Buffering compensates for the difference in transfer speeds between the sender and receiver of the data.
How do I turn off frame buffer? ›...
How to disable Framebuffer
- Open the Grub menu file (IE. /boot/grub/menu. ...
- One of the following options should disable frame buffering: ...
- You would specify one (or more) of the above on the 'kernel' line of the Grub menu file.
How do I permanently change kernel parameters in Linux? ›
Enter the command /sbin/sysctl -a to confirm that the values are set correctly. After updating the values of the kernel parameters in the /etc/sysctl. conf file, either restart the computer, or run the command sysctl -p to make the changes in the /etc/sysctl. conf file available in the active kernel memory.
How do I turn off autorun in Linux? ›- Check the status of srcmstr.service and ctrmc.service. # systemctl status ctrmc.service. ...
- Stop the services. # systemctl stop ctrmc.service. ...
- Disable autostart. # systemctl disable ctrmc.service. ...
- Check if autostart is disabled.
They can be used for off-screen rendering, and they are required for certain advanced rendering algorithms. A framebuffer can use a color buffer to hold the color data for an image, a depth buffer to hold a depth value for each pixel, and something called a stencil buffer (which is not covered in this textbook).
What are types of frame buffers? ›OpenGL has two kinds of framebuffers: the Default Framebuffer, which is provided by the OpenGL Context; and user-created framebuffers called Framebuffer Objects (FBOs). The buffers for default framebuffers are part of the context and usually represent a window or display device.
What is pixel buffer vs framebuffer? ›A Framebuffer Object (note the capitalization: framebuffer is one word, not two) is an object that contains multiple images which can be used as render targets. A Pixel Buffer Object is: A Buffer Object. FBOs are not buffer objects.
What is alternative to Xvfb? ›Faster alternative to xvfb
A potential alternative is to use a combination of VirtualGL and virtual displays from nvidia tools. Note that this may interfere with your display/driver setup, and may not work on cloud VMs ( nvidia-xconfig is not available).
- Run the following command, where sysname is the system name, and n is the display number that you are checking: /usr/lpp/X11/Xamples/bin/xprop -display sysname:n -root | grep VFB.
- If XVFB is running, you will see the following string: XVFB_SCREEN(STRING) = "TRUE" .
- Enter the following command to initiate the installation: $ sudo yum install Xvfb. A password prompt might appear.
- If a password prompt appears, enter the password for the privileged user account on the application server. A confirmation prompt appears.
- Enter Y, and press Enter.
Linux uses ttySx for a serial port device name. For example, COM1 (DOS/Windows name) is ttyS0, COM2 is ttyS1, and so on. USB based serial ports might use a name such as ttySUSB0. All these devices are located under /dev/ directory.
What is the default serial console in Linux? ›Default is 9600n8. The maximum baudrate is 115200. defines that opening /dev/console will get you the current foreground virtual console, and kernel messages will appear on both the VGA console and the 2nd serial port (ttyS1 or COM2) at 9600 baud.
How do I activate my serial port? ›
- From the System Utilities screen, select System Configuration > BIOS/Platform Configuration (RBSU) > BIOS Serial Console and EMS Options > BIOS Serial Console Port.
- Select a setting. Auto. Physical Serial Port. Virtual Serial Port.
- Save your setting.
Xvfb or X virtual framebuffer is a display server implementing the X11 display server protocol. In contrast to other display servers, Xvfb performs all graphical operations in virtual memory without showing any screen output.
What is kernel ring buffer in Linux? ›The kernel ring buffer is a data structure that records messages related to the operation of the kernel. A ring buffer is a special kind of buffer that is always a constant size, removing the oldest messages when new messages are received.
What is a frame buffer Vulkan? ›Framebuffers represent a collection of memory attachments that are used by a render pass instance. Examples of these memory attachments include the color image buffers and depth buffer that we created in previous samples.
What is CPU framebuffer? ›A framebuffer is a continuous memory area, typically located within the address space of the CPU. In case of complex graphics systems (e.g. using OpenGL ES 2.0) a framebuffer is located within a separated video memory. Double-buffering - A technique where the framebuffer consist of two independent pixel buffers.
Does EFI increase performance? ›EFI-equipped engines provide higher power and torque than a carbureted version of the same engine. They optimize air/fuel ratios and ignition timing while compensating for other factors to maintain continuous optimum performance.
Should I Enable EFI? ›EFI allows for much larger boot partition sizes than BIOS. It also makes Secure Boot possible, lessening the risk of the firmware being corrupted or taken over by malware. For these reasons, Microsoft has made UEFI support mandatory for PC manufacturers since Windows 8.
What is the difference between buffers and cache? ›Although they both temporarily store the data, they are not the same. Buffering is mainly used to match the communication speed between the sender and the receiver. On the other hand, cache improves the access speed to frequently used data.
What is the difference between cache and buffer in Linux? ›Buffers are the disk block representation of the data that is stored under the page cache. In addition, the buffer contains the metadata of the files or data which resides under the page cache. On the other hand, a cache is a temporary storage area to store frequently accessed data for rapid access.
What is the difference between cache and buffer memory? ›Buffer is used to compensate for difference in speed between two processes that exchange or use data. Cache is a smaller and fastest memory component in the computer. 2. It is mostly used for input/output processes.
What is refresh or frame buffer? ›
A memory area called refresh buffer or frame buffer stores picture definition. This memory area holds intensity values for all screen points. Stored intensity values are restored from frame buffer and painted on screen taking one row at a time. Each screen point is referred to as pixels.
How do I get my FPS back to normal? ›- Meet the system requirements of your games.
- Turn off fullscreen optimization.
- Scan for malware and virus.
- Disable Intel Turbo Boost technology.
- Check for system file corruption.
- Update your graphics card drivers.
- Cooldown your CPU and GPU.
- Check for your hard drive.
Scroll down and tap “Manage game and add-ons” menu; In the Manage game screen, scroll down and open the “Compatibility options” menu; Toggle FPS Boost and/or Auto HDR on and off; Restart your game for the changes to take effect.
Can I modify Linux kernel? ›Procedure. To update kernel parameters on Red Hat and SUSE Linux: Run the ipcs -l command. Analyze the output to determine if there are any necessary changes required for your system. Comments have been added following the // to show what the parameter names are.
Where are Linux kernel parameters stored? ›Kernel command-line parameters are saved in the boot/grub/grub. cfg configuration file, which is generated by the GRUB2 boot loader.
How do I force a Linux kernel to update? ›- Step 1: Check Your Current Kernel Version. At a terminal window, type: uname –sr. ...
- Step 2: Update the Repositories. At a terminal, type: sudo apt-get update. ...
- Step 3: Run the upgrade. While still in the terminal, type: sudo apt-get dist-upgrade.
The malware on the CD or USB will start installing automatically as soon as you insert it to your device. If this feature is enabled in your device, it will be detected as a vulnerability by many vulnerability scanners. It is a security best practice to disable AutoRun.
How do I disable AutoRun programs? ›On most Windows computers, you can access the Task Manager by pressing Ctrl+Shift+Esc, then clicking the Startup tab. Select any program in the list and click the Disable button if you don't want it to run on startup.
How do I bypass AutoRun? ›Select the Start icon in the lower-left corner, then select the Settings icon in the left pane. Select Devices. Select AutoPlay from the left pane, then select the AutoPlay toggle to turn it Off.
How do I enable Iommu in Linux? ›The steps to activate the Intel IOMMU on a server with an AMD processor are as follows: 1. Boot the server and when prompted, press F1 to enter System Setup. 2. From the UEFI menu, select System Settings → Devices and I/O ports, highlight IOMMU and press Enter to enable the AMD IOMMU as shown in Figure 2.
How do I enable services in Linux? ›
- To start a service in systemd run the command as shown: systemctl start service-name. ...
- To stop the service running service systemctl stop apache2. ...
- To enable apache2 service on boot up run. ...
- To disable apache2 service on boot up run systemctl disable apache2.
- Unpack the tarball with the tar command, as follows: tar xvpzf kexec-tools.tar.gz.
- Change to the kexec-tools directory, as follows: cd kexec-tools-VERSION.
- Configure the package, as follows: ./configure.
- Compile the package, as follows: make.
- Install the package, as follows: make install.
The main difference between interrupt and polling is that, in the case of an interrupt, the system informs the CPU that it needs attention, while talking about polling, the CPU constantly inspects the status of the system to find whether it needs attention.
How do I see interrupts in Linux? ›The /proc/interrupts display shows how many interrupts have been delivered to each CPU on the system. As you can see from the output, the Linux kernel generally handles interrupts on the first CPU as a way of maximizing cache locality.
What are all the interrupts in Linux? ›Types of interrupts
A Linux kernel needs to handle three kinds of interrupts: software interrupts, hardware interrupts, and exceptions.
The Input-Output Memory Management Unit (IOMMU) is a hardware component that performs address translation from I/O device virtual addresses to physical addresses. This hardware-assisted I/O address translation dramatically improves the system performance within a virtual environment.
Does IOMMU affect performance? ›Although they provide valuable services, IOMMUs can impose a performance penalty due to the extra memory accesses required to perform DMA operations. The exact perfor-mance degradation depends on the IOMMU design, its caching architecture, the way it is programmed and the workload.
Do I need to enable IOMMU? ›The only way IOMMU will help is if you start assigning HW resources directly to the VM. Just having it available doesn't make things faster. It would help to know exactly what Motherboard/CPU is advertising this feature. IOMMU is a system specific IO mapping mechanism and can be used with most devices.
How can I see all services in Linux? ›To see all running services on a Linux system with systemd, use the command "systemctl --type=service --state=running". This will show you each active service's name, load, sub-state, and description. You can also change the state value to see services that are dead, exited, failed, or inactive.
How can I see what services are running in Linux? ›Type the ps aux to see all running process in Linux. Alternatively, you can issue the top command or htop command to view running process in Linux.
What is systemctl used for? ›
The systemctl command manages both system and service configurations, enabling administrators to manage the OS and control the status of services. Further, systemctl is useful for troubleshooting and basic performance tuning.
What is kexec vs kdump? ›Kdump works similarly to Kexec (see Chapter 17, Kexec and Kdump). The capture kernel is executed after the running production kernel crashes. The difference is that Kexec replaces the production kernel with the capture kernel. With Kdump, you still have access to the memory space of the crashed production kernel.
What is kexec used for? ›Kexec is a system call that enables you to load and boot into another kernel from the currently running kernel. This is useful for kernel developers or other people who need to reboot very quickly without waiting for the whole BIOS boot process to finish.
How do I trigger a Linux script? ›- Create a new file called demo.sh using a text editor such as nano or vi in Linux: nano demo.sh.
- Add the following code: ...
- Set the script executable permission by running chmod command in Linux: chmod +x demo.sh.
- Execute a shell script in Linux: ./demo.sh.