rpi: improve documentation
Signed-off-by: Mathieu Benoit <mathieu.benoit@savoirfairelinux.com>
[yann.morin.1998@free.fr: further improvements for readability and
completeness]
Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
This commit is contained in:
mathieu benoit
Peter Korsgaard
parent
856294dedf
commit
7f02c73f8d
@ -4,124 +4,125 @@ 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 a prior choice to make, will you 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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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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Volatile rootfs
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How to build it
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===============
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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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You need to use the rpi_defconfig, to do so:
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* make rpi_defconfig
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The rpi_defconfig configuration is a minimal configuration with all that
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is required to bring the Raspberry Pi. You should base your work on this
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defconfig:
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Then, you need to select the kind of images you want:
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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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$ make rpi_defconfig
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What is generated
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-----------------
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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
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+-- rpi-firmware
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| +-- bootcode.bin
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| +-- config.txt
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| +-- fixup_cd.dat
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| +-- fixup.dat
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| +-- start_cd.elf
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| `-- start.elf
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| +-- bootcode.bin
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| +-- config.txt
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| +-- fixup_cd.dat
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| +-- fixup.dat
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| +-- start_cd.elf
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| `-- start.elf
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`-- zImage
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Note : rootfs.tar will only be there if you kept "tar the root filesystem"
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option selected in "Filesystem images".
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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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Where should the binaries be copied on the SDCard
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-------------------------------------------------
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Prepare you SDCard
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==================
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Your SDCard must have its first partition using fat32 and marked bootable.
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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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At the root of the partition, the RaspberryPi must find the following files:
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In summary, your SDCard must have first partition in fat32 and marked bootable.
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* bootcode.bin
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* config.txt
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* fixup_cd.dat
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* fixup.dat
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* start_cd.elf
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* start.elf
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* zImage
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So you should copy the entire content of output/images/rpi-firmware along with
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zImage.
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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 bootable.
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is that the first partition must be using fat32 and be bootable.
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Persistent rootfs
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=================
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Mount the partitions (adjust 'sdX' to match your SDcard device):
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How to build it
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---------------
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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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You only need to use the rpi_defconfig, to do so:
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* make rpi_defconfig
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Install the binaries to the SDCard
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----------------------------------
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What is generated
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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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After building, you should obtain this tree:
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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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output/images/
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+-- rootfs.tar
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+-- rpi-firmware
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| +-- bootcode.bin
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| +-- config.txt
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| +-- fixup_cd.dat
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| +-- fixup.dat
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| +-- start_cd.elf
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| `-- start.elf
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`-- zImage
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For example:
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Where should the binaries be copied on the SDCard
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-------------------------------------------------
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$ cp output/images/rpi-firmware/* /mnt/mountpointboot
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$ cp output/images/zImage /mnt/mountpointboot/zImage.img
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Your SDCard must have its first partition using fat32 and marked bootable.
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It should also have another partition which will contain your rootfs, it should
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be partitioned as ext4.
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Note: The default name is kernel.img.
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Actually, the name is zImage and it's define in the file config.txt like:
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kernel=zImage
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Boot partition
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~~~~~~~~~~~~~~
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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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The first partition will contain everything used to boot the RaspberryPi.
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You must copy theses files at the root of partition:
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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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* bootcode.bin
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* config.txt
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* fixup_cd.dat
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* fixup.dat
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* start_cd.elf
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* start.elf
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* zImage
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$ sudo tar xf rootfs.tar -C /mnt/mountpointroot
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So you should copy the entire content of output/images/rpi-firmware along with
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zImage.
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Finish
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======
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Rootfs partition
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~~~~~~~~~~~~~~~~
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Unmount all the partitions:
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The second partition will contain your rootfs.
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Simply extract (as root!) the contents of the rootfs.tar archive
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into this partition.
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$ sudo umount /mnt/mountpointboot
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$ sudo umount /mnt/mountpointroot (only for persistent rootfs)
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For example: (Assuming mountpoint is a directory and exist)
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$ sudo mount /dev/sdXY /mnt/mountpoint
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$ sudo tar xf rootfs.tar -C /mnt/mountpoint
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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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