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Diffstat (limited to 'meta-raspberrypi/docs/extra-build-config.md')
| -rw-r--r-- | meta-raspberrypi/docs/extra-build-config.md | 16 |
1 files changed, 16 insertions, 0 deletions
diff --git a/meta-raspberrypi/docs/extra-build-config.md b/meta-raspberrypi/docs/extra-build-config.md index dc5d33a6f3..3d66ffde9a 100644 --- a/meta-raspberrypi/docs/extra-build-config.md +++ b/meta-raspberrypi/docs/extra-build-config.md @@ -74,6 +74,22 @@ To remove (or adjust) this delay set these variables in local.conf: BOOT_DELAY = "0" BOOT_DELAY_MS = "0" +## Boot media + +The Raspberry Pi 4 board can load the boot image files from SD card and USB memory. +By default SD card media is used as boot media. + +To switch the boot media from SD card to USB memory, the following variables are supported +in local.conf: `CMDLINE_ROOT_PARTITION` and `BOOT_MEDIA`. +The default value of `CMDLINE_ROOT_PARTITION` is "/dev/mmcblk0p2" to mount SD card. If you want to mount USB memory partition, set CMDLINE_ROOT_PARTITION to "/dev/sda2". +`BOOT_MEDIA` allows `mmc` and `usb`. The "mmc" is required to load an image from the SD card, following the u-boot specification. Similarly, if you want to load a boot image file from USB memory, set BOOT_MEDIA to "usb". + +For example, if you want to use USB boot, please define +the following parameters in your local.conf file. + + CMDLINE_ROOT_PARTITION = "/dev/sda2" + BOOT_MEDIA = "usb" + ## Set overclocking options The Raspberry Pi can be overclocked. As of now overclocking up to the "Turbo |