RPiconfig

The Raspberry Pi config.txt file is read by the GPU before the ARM core is initialised. It can be used to set various system configuration parameters.

This file is an optional file on the boot partition. It would normally be accessible as /boot/config.txt from Linux.

To edit the configuration file, see the instructions at R-Pi_ConfigurationFile.

You can get your current active settings with the following commands: vcgencmd get_config - lists a specific config value. E.g. vcgencmd get_config arm_freq vcgencmd get_config int - lists all the integer config options that are set (non-zero) vcgencmd get_config str - lists all the string config options that are set (non-null)

=File format=

The format is "property=value" where value is an integer. You may specify only one option per line. Comments may be added by starting a line with the '#' character.

Note: In the newer Raspberry Pi models there is # before every line, if you want changes to have an affect then 'uncomment' meaning remove the #.

Here is an example file '''# Set stdv mode to PAL (as used in Europe) sdtv_mode=2 hdmi_drive=2 hdmi_group=2 hdmi_mode=16 overscan_left=20 overscan_right=12 overscan_top=10 overscan_bottom=10'''
 * 1) Force the monitor to HDMI mode so that sound will be sent over HDMI cable
 * 1) Set monitor mode to DMT
 * 1) Set monitor resolution to 1024x768 XGA 60Hz (HDMI_DMT_XGA_60)
 * 1) Make display smaller to stop text spilling off the screen

And here is another example file, containing extended documentation of features.

=Memory=

disable_l2cache	 disable ARM access to GPU's L2 cache. Needs corresponding L2 disabled kernel. Default 0

gpu_mem	 GPU memory in megabyte. Sets the memory split between the ARM and GPU. ARM gets the remaining memory. Min 16. Default 64

gpu_mem_256	GPU memory in megabyte for the 256MB Raspberry Pi. Ignored by the 512MB RP. Overrides gpu_mem. Max 192. Default not set

gpu_mem_512	GPU memory in megabyte for the 512MB Raspberry Pi. Ignored by the 256MB RP. Overrides gpu_mem. Max 448. Default not set

disable_pvt      Disable adjusting the refresh rate of RAM every 500ms (measuring RAM temparature).

CMA - Dynamic Memory Split
The firmware and kernel as of 19. November 2012 supports CMA, which means the memory split between ARM and GPU is managed dynamically at runtime. You can find an example config.txt here.

cma_lwm	When GPU has less than cma_lwm (low water mark) memory available it will request some from ARM.

cma_hwm	When GPU has more than cma_hwm (high water mark) memory available it will release some to ARM.

The following options need to be in cmdline.txt for CMA to work: coherent_pool=6M smsc95xx.turbo_mode=N

=Video=

Video mode options
sdtv_mode defines the TV standard for composite output (default=0) sdtv_mode=0   Normal NTSC sdtv_mode=1   Japanese version of NTSC – no pedestal sdtv_mode=2   Normal PAL sdtv_mode=3   Brazilian version of PAL – 525/60 rather than 625/50, different subcarrier

sdtv_aspect defines the aspect ratio for composite output (default=1) sdtv_aspect=1 4:3 sdtv_aspect=2 14:9 sdtv_aspect=3 16:9

sdtv_disable_colourburst disables colour burst on composite output. The picture will be monochrome, but possibly sharper sdtv_disable_colourburst=1 colour burst is disabled

hdmi_safe Use "safe mode" settings to try to boot with maximum hdmi compatibility. This is the same as the combination of: hdmi_force_hotplug=1, config_hdmi_boost=4, hdmi_group=2, hdmi_mode=4, disable_overscan=0 hdmi_safe=1

hdmi_ignore_edid Enables the ignoring of EDID/display data if your display is a crappy Chinese one hdmi_ignore_edid=0xa5000080

hdmi_edid_file when set to 1, will read the edid data from the edid.dat file instead of from the monitor. hdmi_edid_file=1

hdmi_force_edid_audio Pretends all audio formats are supported by display, allowing passthrough of DTS/AC3 even when not reported as supported. hdmi_force_edid_audio=1

avoid_edid_fuzzy_match Avoid fuzzy matching of modes described in edid. Picks the standard mode with matching resolution and closest framerate even if blanking is wrong. avoid_edid_fuzzy_match=1

hdmi_ignore_cec_init Doesn't sent initial active source message. Avoids bringing (CEC enabled) TV out of standby and channel switch when rebooting. hdmi_ignore_cec_init=1

hdmi_ignore_cec Pretends CEC is not supported at all by TV. No CEC functions will be supported. hdmi_ignore_cec=1

hdmi_force_hotplug Pretends HDMI hotplug signal is asserted so it appears a HDMI display is attached hdmi_force_hotplug=1 Use HDMI mode even if no HDMI monitor is detected

hdmi_ignore_hotplug Pretends HDMI hotplug signal is not asserted so it appears a HDMI display is not attached hdmi_ignore_hotplug=1 Use composite mode even if HDMI monitor is detected

hdmi_pixel_encoding Force the pixel encoding mode. By default it will use the mode requested from edid so shouldn't need changing. hdmi_pixel_encoding=0 RGB limited  (16-235) hdmi_pixel_encoding=1 RGB full     ( 0-255) hdmi_pixel_encoding=2 YCbCr limited (16-235) hdmi_pixel_encoding=3 YCbCr limited ( 0-255)

hdmi_drive chooses between HDMI and DVI modes hdmi_drive=1 Normal DVI mode (No sound) hdmi_drive=2 Normal HDMI mode (Sound will be sent if supported and enabled)

hdmi_group defines the HDMI type

Not specifying the group, or setting to 0 will use the preferred group reported by the edid.

hdmi_group=1  CEA hdmi_group=2  DMT

hdmi_mode defines screen resolution in CEA or DMT format

These values are valid if hdmi_group=1 (CEA) hdmi_mode=1   VGA hdmi_mode=2   480p  60Hz hdmi_mode=3   480p  60Hz  H hdmi_mode=4    720p  60Hz hdmi_mode=5   1080i 60Hz hdmi_mode=6   480i  60Hz hdmi_mode=7   480i  60Hz  H hdmi_mode=8    240p  60Hz hdmi_mode=9   240p  60Hz  H hdmi_mode=10   480i  60Hz  4x hdmi_mode=11  480i  60Hz  4x H hdmi_mode=12   240p  60Hz  4x hdmi_mode=13  240p  60Hz  4x H hdmi_mode=14   480p  60Hz  2x hdmi_mode=15  480p  60Hz  2x H hdmi_mode=16   1080p 60Hz hdmi_mode=17  576p  50Hz hdmi_mode=18  576p  50Hz  H hdmi_mode=19   720p  50Hz hdmi_mode=20  1080i 50Hz hdmi_mode=21  576i  50Hz hdmi_mode=22  576i  50Hz  H hdmi_mode=23   288p  50Hz hdmi_mode=24  288p  50Hz  H hdmi_mode=25   576i  50Hz  4x hdmi_mode=26  576i  50Hz  4x H hdmi_mode=27   288p  50Hz  4x hdmi_mode=28  288p  50Hz  4x H hdmi_mode=29   576p  50Hz  2x hdmi_mode=30  576p  50Hz  2x H hdmi_mode=31   1080p 50Hz hdmi_mode=32  1080p 24Hz hdmi_mode=33  1080p 25Hz hdmi_mode=34  1080p 30Hz hdmi_mode=35  480p  60Hz  4x hdmi_mode=36  480p  60Hz  4xH hdmi_mode=37  576p  50Hz  4x hdmi_mode=38  576p  50Hz  4x H hdmi_mode=39   1080i 50Hz  reduced blanking hdmi_mode=40  1080i 100Hz hdmi_mode=41  720p  100Hz hdmi_mode=42  576p  100Hz hdmi_mode=43  576p  100Hz H hdmi_mode=44   576i  100Hz hdmi_mode=45  576i  100Hz H hdmi_mode=46   1080i 120Hz hdmi_mode=47  720p  120Hz hdmi_mode=48  480p  120Hz hdmi_mode=49  480p  120Hz H hdmi_mode=50   480i  120Hz hdmi_mode=51  480i  120Hz H hdmi_mode=52   576p  200Hz hdmi_mode=53  576p  200Hz H hdmi_mode=54   576i  200Hz hdmi_mode=55  576i  200Hz H hdmi_mode=56   480p  240Hz hdmi_mode=57  480p  240Hz H hdmi_mode=58   480i  240Hz hdmi_mode=59  480i  240Hz H H means 16:9 variant (of a normally 4:3 mode). 2x means pixel doubled (i.e. higher clock rate, with each pixel repeated twice) 4x means pixel quadrupled (i.e. higher clock rate, with each pixel repeated four times)

These values are valid if hdmi_group=2 (DMT) hdmi_mode=1   640x350   85Hz hdmi_mode=2   640x400   85Hz hdmi_mode=3   720x400   85Hz hdmi_mode=4   640x480   60Hz hdmi_mode=5   640x480   72Hz hdmi_mode=6   640x480   75Hz hdmi_mode=7   640x480   85Hz hdmi_mode=8   800x600   56Hz hdmi_mode=9   800x600   60Hz hdmi_mode=10  800x600   72Hz hdmi_mode=11  800x600   75Hz hdmi_mode=12  800x600   85Hz hdmi_mode=13  800x600   120Hz hdmi_mode=14  848x480   60Hz hdmi_mode=15  1024x768  43Hz  DO NOT USE hdmi_mode=16  1024x768  60Hz hdmi_mode=17  1024x768  70Hz hdmi_mode=18  1024x768  75Hz hdmi_mode=19  1024x768  85Hz hdmi_mode=20  1024x768  120Hz hdmi_mode=21  1152x864  75Hz hdmi_mode=22  1280x768        reduced blanking hdmi_mode=23  1280x768  60Hz hdmi_mode=24  1280x768  75Hz hdmi_mode=25  1280x768  85Hz hdmi_mode=26  1280x768  120Hz reduced blanking hdmi_mode=27  1280x800        reduced blanking hdmi_mode=28  1280x800  60Hz hdmi_mode=29  1280x800  75Hz hdmi_mode=30  1280x800  85Hz hdmi_mode=31  1280x800  120Hz reduced blanking hdmi_mode=32  1280x960  60Hz hdmi_mode=33  1280x960  85Hz hdmi_mode=34  1280x960  120Hz reduced blanking hdmi_mode=35  1280x1024 60Hz hdmi_mode=36  1280x1024 75Hz hdmi_mode=37  1280x1024 85Hz hdmi_mode=38  1280x1024 120Hz reduced blanking hdmi_mode=39  1360x768  60Hz hdmi_mode=40  1360x768  120Hz reduced blanking hdmi_mode=41  1400x1050       reduced blanking hdmi_mode=42  1400x1050 60Hz hdmi_mode=43  1400x1050 75Hz hdmi_mode=44  1400x1050 85Hz hdmi_mode=45  1400x1050 120Hz reduced blanking hdmi_mode=46  1440x900        reduced blanking hdmi_mode=47  1440x900  60Hz hdmi_mode=48  1440x900  75Hz hdmi_mode=49  1440x900  85Hz hdmi_mode=50  1440x900  120Hz reduced blanking hdmi_mode=51  1600x1200 60Hz hdmi_mode=52  1600x1200 65Hz hdmi_mode=53  1600x1200 70Hz hdmi_mode=54  1600x1200 75Hz hdmi_mode=55  1600x1200 85Hz hdmi_mode=56  1600x1200 120Hz reduced blanking hdmi_mode=57  1680x1050       reduced blanking hdmi_mode=58  1680x1050 60Hz hdmi_mode=59  1680x1050 75Hz hdmi_mode=60  1680x1050 85Hz hdmi_mode=61  1680x1050 120Hz reduced blanking hdmi_mode=62  1792x1344 60Hz hdmi_mode=63  1792x1344 75Hz hdmi_mode=64  1792x1344 120Hz reduced blanking hdmi_mode=65  1856x1392 60Hz hdmi_mode=66  1856x1392 75Hz hdmi_mode=67  1856x1392 120Hz reduced blanking hdmi_mode=68  1920x1200       reduced blanking hdmi_mode=69  1920x1200 60Hz hdmi_mode=70  1920x1200 75Hz hdmi_mode=71  1920x1200 85Hz hdmi_mode=72  1920x1200 120Hz reduced blanking hdmi_mode=73  1920x1440 60Hz hdmi_mode=74  1920x1440 75Hz hdmi_mode=75  1920x1440 120Hz reduced blanking hdmi_mode=76  2560x1600       reduced blanking hdmi_mode=77  2560x1600 60Hz hdmi_mode=78  2560x1600 75Hz hdmi_mode=79  2560x1600 85Hz hdmi_mode=80  2560x1600 120Hz reduced blanking hdmi_mode=81  1366x768  60Hz hdmi_mode=82  1080p     60Hz hdmi_mode=83  1600x900        reduced blanking hdmi_mode=84  2048x1152       reduced blanking hdmi_mode=85  720p      60Hz hdmi_mode=86  1366x768        reduced blanking

overscan_left	 number of pixels to skip on left

overscan_right	 number of pixels to skip on right

overscan_top	 number of pixels to skip on top

overscan_bottom	 number of pixels to skip on bottom

framebuffer_width	 console framebuffer width in pixels. Default is display width minus overscan.

framebuffer_height	 console framebuffer height in pixels. Default is display height minus overscan.

framebuffer_depth	 console framebuffer depth in bits per pixel. Default is 16. 8bit is valid, but default RGB palette makes an unreadable screen. 24bit looks better but has corruption issues as of 20120615. 32bit has no corruption issues but needs framebuffer_ignore_alpha=1 and shows the wrong colors as of 20120615.

framebuffer_ignore_alpha set to 1 to disable alpha channel. Helps with 32bit.

test_mode	 enable test sound/image during boot for manufacturing test.

disable_overscan	 set to 1 to disable overscan.

config_hdmi_boost		configure the signal strength of the HDMI interface. Default is 0. Try 4 if you have interference issues with hdmi. 7 is the maximum.

display_rotate rotates the display clockwise on the screen (default=0) or flips the display. display_rotate=0       Normal display_rotate=1       90 degrees display_rotate=2       180 degrees display_rotate=3       270 degrees display_rotate=0x10000 horizontal flip display_rotate=0x20000 vertical flip

Note: the 90 and 270 degrees rotation options require additional memory on GPU, so won't work with the 16M GPU split. Probably the reason for:
 * Crashes my RPI before Linux boots if set to "1" -- REW 20120913.

Which values are valid for my monitor?
Your HDMI monitor may support only a limited set of formats. To find out which formats are supported, use the following method.

/opt/vc/bin/tvservice -m CEA /opt/vc/bin/tvservice -m DMT /opt/vc/bin/tvservice -s /opt/vc/bin/tvservice -d edid.dat /opt/vc/bin/edidparser edid.dat The edid.dat should also be provided when troubleshooting problems with the default HDMI mode
 * Set the output format to VGA 60Hz (hdmi_group=1 hdmi_mode=1) and boot up the Raspberry Pi
 * Enter the following command to give a list of CEA supported modes
 * Enter the following command to give a list of DMT supported modes
 * Enter the following command to show your current state
 * Enter the following commands to dump more detailed information from your monitor

=Licensed Codecs= Hardware decoding of additional codecs can be enabled by purchasing a license that is locked to the CPU serial number of your Raspberry Pi.

decode_MPG2 License key to allow hardware MPEG-2 decoding. decode_MPG2=0x12345678

decode_WVC1 License key to allow hardware VC-1 decoding. decode_WVC1=0x12345678

License setup for SD-card sharing between multiple Pis. Maximum of 8 licenses at once. decode_XXXX=0x12345678,0xabcdabcd,0x87654321,...

=Boot= disable_commandline_tags stop start.elf from filling in ATAGS (memory from 0x100) before launching kernel

cmdline                (string) command line parameters. Can be used instead of cmdline.txt file

kernel                 (string) alternative name to use when loading kernel. Default "kernel.img"

kernel_address         address to load kernel.img file at

kernel_old             (bool) if 1, load kernel at 0x0

ramfsfile              (string) ramfs file to load

ramfsaddr              address to load ramfs file at

initramfs              (string address) ramfs file and adress to load it at (it's like ramfsfile+ramfsaddr in one option). NOTE: this option uses different syntax than all other options - you should not use "=" character here. Example: initramfs initramf.gz 0x00800000

device_tree_address    address to load device_tree at

init_uart_baud         initial uart baud rate. Default 115200

init_uart_clock        initial uart clock. Default 3000000 (3Mhz)

init_emmc_clock        initial emmc clock. Default 100000000 (100MHz)

boot_delay             wait for given number of seconds in start.elf before loading kernel. delay = 1000 * boot_delay + boot_delay_ms. Default 1

boot_delay_ms          wait for given number of milliseconds in start.elf before loading kernel. Default 0

avoid_safe_mode        if set to 1, safe_mode boot won't be enabled. Default 0

=Overclocking= NOTE: Setting any of the parameters which overvolt your Raspberry Pi will set a permanent bit within the SOC, making it posibly to detect that you Pi has been overclocked. This was meant to void warranty if the device has been overclocked. Since 19th of September 2012 you can overclock your Pi without affecting your warranty

The latest kernel has a cpufreq kernel driver with the "ondemand" governor enabled by default. It has no effect if you have no overclock settings. But when you do, the arm frequency will vary with processor load. Non default values are only used when needed according to the used governor. You can adjust the minimum values with the *_min config options or disable dynamic clocking with force_turbo=1.

Overclock and overvoltage will be disabled at runtime when the SoC reaches 85°C to cool it down. You should not hit the limit, even with maximum settings at 25°C ambient temperature.

force_turbo mode
force_turbo=0 enables dynamic clocks and voltage for the ARM core, GPU core and SDRAM. When busy, ARM frequency go up to "arm_freq" and down to "arm_freq_min" on idle. "core_freq", "sdram_freq" and "over_voltage" behave the same. "over_voltage" is limited to 6 (1.35V). Non default values for the h264/v3d/isp parts are ignored. force_turbo=1 disables dynamic clocking, so all frequencies and voltages stay high. Overclocking of h264/v3d/isp GPU parts is allowed as well as setting "over_voltage" to 8 (1.4V).

Clocks relationship
The GPU core, h264, v3d and isp share a PLL, therefore need to have related frequencies. ARM, SDRAM and GPU each have their own PLLs and can have unrelated frequencies.

The following is not necessary with "avoid_pwm_pll=1".

pll_freq = floor(2400 / (2 * core_freq)) * (2 * core_freq) gpu_freq = pll_freq / [even number]

The effective gpu_freq is automatically rounded to nearest even integer, so asking for core_freq=500 and gpu_freq=300 will result in divisor of 2000/300 = 6.666 => 6 and so 333.33MHz.

Tested values
The following table shows some successfull attempts of overclocking, which can be used for orientation. These settings may not work on every device and can shorten the lifetime of the Broadcom SoC.

There are reports that Hynix RAM is not as good as Samsung RAM for overclocking.

=References=