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Copy file name to clipboardExpand all lines: configuration/cmdline-txt.md
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@@ -4,7 +4,9 @@ The Linux kernel accepts a command line of parameters during boot. On the Raspbe
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```
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sudo nano /boot/cmdline.txt
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```
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Note that we have to use `sudo` to edit anything in the boot partition.
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Note that we have to use `sudo` to edit anything in the boot partition, and that all parameters in `cmdline.txt` must be on the same line (no carriage returns).
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The command line that was passed to the kernel at boot time can be displayed using `cat /proc/cmdline`. It will not be exactly the same as that in `cmdline.txt` as the firmware can make changes to it prior to launching the kernel.
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## Command Line Options
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- elevator: specifies the I/O scheduler to use. `elevator=deadline` means the kernel imposes a deadline on all I/O operations to prevent request starvation.
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- quiet: sets the default kernel log level to `KERN_WARNING`, which suppresses all but very serious log messages during boot.
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#### Display Entries in FKMS and KMS modes
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The firmware automatically adds a preferred resolution and overscan settings via an entry such as:
This default entry can be modified by duplicating the entry above manually in /boot/cmdline.txt and making required changes to the margin parameters. In addition, it is possible to add rotation and reflect parameters as documented in the standard [Linux framebuffer documentation](https://github.com/raspberrypi/linux/blob/rpi-4.19.y/Documentation/fb/modedb.txt). By default the `margin_*` options are set from the `overscan` entries in config.txt, if present. The firmware can be prevented from making any KMS specific changes to the command line by adding `disable_fw_kms_setup=1` to `config.txt`
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