b8f45e7a09
The rootfs.tar file is located under ./output/images/. Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com> Acked-by: "Yann E. MORIN" <yann.morin.1998@free.fr> Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
149 lines
4.1 KiB
Plaintext
149 lines
4.1 KiB
Plaintext
RaspberryPi
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Intro
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=====
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To be able to use your RaspberryPi board with the images generated by
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Buildroot, you have to choose whether you will use:
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* Volatile rootfs in RAM (the rootfs is an initramfs) or
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* Persistent rootfs on the SDCard
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Also, a good source of information is http://elinux.org/R-Pi_Hub
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How to build it
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===============
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Configure Buildroot
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-------------------
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The raspberrypi_defconfig configuration is a minimal configuration with
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all that is required to bring the Raspberry Pi. You should base your
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work on this defconfig:
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$ make raspberrypi_defconfig
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Alternatively, if you want to test support for the Device Tree:
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$ make raspberrypi_dt_defconfig
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If you want to use a persistent rootfs, skip to "Build the rootfs", below.
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For a volatile rootfs, you have to slightly adjust the configuration:
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$ make menuconfig
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* Select "Filesystem images"
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* Select "initial RAM filesystem linked into linux kernel"
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You may also deselect "tar the root filesystem".
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Build the rootfs
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----------------
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Note: you will need to have access to the network, since Buildroot will
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download the packages' sources.
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You may now build your rootfs with:
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$ make
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(This may take a while; consider getting yourself a coffee ;-) )
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Result of the build
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-------------------
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After building, you should obtain this tree:
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output/images/
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+-- rootfs.tar [0]
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+-- rpi-firmware/
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| +-- bcm2708-rpi-b.dtb [1]
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| +-- bcm2708-rpi-b-plus.dtb [1]
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| +-- bootcode.bin
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| +-- config.txt
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| +-- fixup.dat
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| `-- start.elf
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`-- zImage
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[0] Note for Volatile: rootfs.tar will only be there if you kept
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"tar the root filesystem" option selected in "Filesystem images".
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[1] The DTBs (Device Tree Blobs) will only be present if you setup
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Buildroot to install the DTBs from the rpi-firmware package, and
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will only be used if your kernel has support for the Device Tree.
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Prepare you SDCard
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==================
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For more information, visit
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http://elinux.org/RPi_Advanced_Setup#Advanced_SD_card_setup
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In summary, your SDCard must have first partition in fat32 and marked bootable.
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Create the required partitions:
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- for a persistent rootfs, 10MiB is enough memory for the boot fat32
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partition, and a second partition is required for the root filesystem
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- for a volatile rootfs, 50MiB is required for the boot fat32 partition
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Note: You can create any number of partitions you desire, the only requirement
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is that the first partition must be using fat32 and be bootable.
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Mount the partitions (adjust 'sdX' to match your SDcard device):
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$ sudo mount /dev/sdX1 /mnt/mountpointboot
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$ sudo mount /dev/sdX2 /mnt/mountpointroot (only for persistent rootfs)
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Install the binaries to the SDCard
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----------------------------------
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At the root of the boot partition, the RaspberryPi must find the following
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files:
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* bcm2708-rpi-b.dtb [2]
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* bcm2708-rpi-b-plus.dtb [2]
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* bootcode.bin
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* config.txt
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* fixup.dat
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* start.elf
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* zImage
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[2] Only needed if your kernel has support for the Device Tree.
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For example:
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$ cp output/images/rpi-firmware/* /mnt/mountpointboot
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If your kernel does *not* have support for the Device Tree, then install
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it with:
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$ cp output/images/zImage /mnt/mountpointboot
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If your kernel *does* have support for the Device Tree, then install it
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with:
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$ ./output/host/usr/bin/mkknlimg output/images/zImage /mnt/mountpointboot/zImage
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Note: The kernel image file name is defined in config.txt like this:
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kernel=zImage
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If you use a volatile rootfs, Skip to "Finish", below. For a persistent
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rootfs, there are further steps to do.
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Extract (as root!) the contents of the rootfs.tar archive into the second
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partition you created above:
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$ sudo tar xf ./output/images/rootfs.tar -C /mnt/mountpointroot
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Finish
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======
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Unmount all the partitions:
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$ sudo umount /mnt/mountpointboot
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$ sudo umount /mnt/mountpointroot (only for persistent rootfs)
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And eject your SDcard from your computer SDcard reader.
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Insert the SDcard into your Raspberry Pi, and power it up. Your new system
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should come up, now.
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