64-bit Mainline kernel on Raspberry Pi 3
2018-10-06

64-bit Mainline kernel on Raspberry Pi 3

kernel raspberrypi linux

I’ve struggled a little recently on running vanilla kernel on Raspberry Pi 3. Still I didn’t completely understand the internals. Anyway sharing the steps may be useful for someone like me.

Download toolchain and rootfs from Linaro.

And clone following repos

I’ve created a directory structure as below. You can have similar one based on your convenience.

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$ ls ~/Desktop/kernel/
total 44K
drwxr-xr-x  2 kaba kaba 4.0K Sep 23 20:04 downloads
drwxrwxr-x  2 kaba kaba 4.0K Oct  4 10:22 firmware
drwxr-xr-x 22 kaba kaba 4.0K Oct  6 11:55 kernel_out
drwxr-xr-x 18 kaba kaba 4.0K Sep 12  2013 rootfs
drwxr-xr-x 26 kaba kaba 4.0K Oct  3 21:30 rpi_kernel
drwxr-xr-x  2 kaba kaba 4.0K Oct  7 12:13 rpi_out
drwxr-xr-x  3 kaba kaba 4.0K Sep 23 19:43 toolchain
drwxr-xr-x 26 kaba kaba 4.0K Oct  3 22:04 vanila_kernel
kaba@kaba-Vostro-1550:~/Desktop/kernel
$
Directory Purpose
downloads Having tarballs of rootfs and toolchain
firmware boot directory of Raspberry Pi firmware repo
kernel_out Output directory for Mainline kernel
rootfs rootfs tarball extracted
rpi_kernel Raspberry Pi kernel repo
rpi_out Output directory for Raspberry Pi kernel
toolchain toolchain tarball extracted
vanilla_kernel Mainline kernel repo

Export PATH variable to include toolchain directory.

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$ echo $PATH
/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin:/home/kaba/Desktop/kernel/toolchain/gcc-linaro-7.3.1-2018.05-x86_64_aarch64-linux-gnu/bin/
kaba@kaba-Vostro-1550:~/Desktop/kernel/vanila_kernel
$

Configure and build 64-bit Vanilla kernel.

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kaba@kaba-Vostro-1550:~/Desktop/kernel/vanila_kernel
$ make O=../kernel_out ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- defconfig
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kaba@kaba-Vostro-1550:~/Desktop/kernel/vanila_kernel
$ make -j4 O=../kernel_out ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu-

Change the suffix to -j according to your machine. And wait for the build to complete.

Now build device-tree in Raspberry Pi kernel repo.

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kaba@kaba-Vostro-1550:~/Desktop/kernel/rpi_kernel
$ make O=../rpi_out ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- defconfig
make[1]: Entering directory '/home/kaba/Desktop/kernel/rpi_out'
  HOSTCC  scripts/basic/fixdep
  GEN     ./Makefile
  HOSTCC  scripts/kconfig/conf.o
  YACC    scripts/kconfig/zconf.tab.c
  LEX     scripts/kconfig/zconf.lex.c
  HOSTCC  scripts/kconfig/zconf.tab.o
  HOSTLD  scripts/kconfig/conf
*** Default configuration is based on 'defconfig'
#
# configuration written to .config
#
make[1]: Leaving directory '/home/kaba/Desktop/kernel/rpi_out'
kaba@kaba-Vostro-1550:~/Desktop/kernel/rpi_kernel
$ make O=../rpi_out ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- dtbs
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Partition your memory card into two. The first one should be FAT32 and second one should be EXT4. The first partition should be a boot partition.

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balakumaran@balakumaran-USB:~/Desktop/RPi/linux_build$ sudo parted /dev/sdd
[sudo] password for balakumaran: 
GNU Parted 3.2
Using /dev/sdd
Welcome to GNU Parted! Type 'help' to view a list of commands.
(parted) print                                                            
Model: MXT-USB Storage Device (scsi)
Disk /dev/sdd: 31.9GB
Sector size (logical/physical): 512B/512B
Partition Table: msdos
Disk Flags: 

Number  Start   End     Size    Type     File system  Flags
 1      1049kB  106MB   105MB   primary  fat32        boot, lba
 2      106MB   31.9GB  31.8GB  primary

(parted) help rm                                                          
  rm NUMBER                                delete partition NUMBER

        NUMBER is the partition number used by Linux.  On MS-DOS disk labels, the primary partitions number from 1 to 4, logical partitions from 5 onwards.
(parted) rm 1                                                             
(parted) rm 2                                                             
(parted) print
Model: MXT-USB Storage Device (scsi)
Disk /dev/sdd: 31.9GB
Sector size (logical/physical): 512B/512B
Partition Table: msdos
Disk Flags: 

Number  Start  End  Size  Type  File system  Flags

(parted) help mkpart
  mkpart PART-TYPE [FS-TYPE] START END     make a partition

        PART-TYPE is one of: primary, logical, extended
        FS-TYPE is one of: zfs, btrfs, nilfs2, ext4, ext3, ext2, fat32, fat16, hfsx, hfs+, hfs, jfs, swsusp, linux-swap(v1), linux-swap(v0), ntfs, reiserfs, freebsd-ufs, hp-ufs, sun-ufs,
        xfs, apfs2, apfs1, asfs, amufs5, amufs4, amufs3, amufs2, amufs1, amufs0, amufs, affs7, affs6, affs5, affs4, affs3, affs2, affs1, affs0, linux-swap, linux-swap(new), linux-swap(old)
        START and END are disk locations, such as 4GB or 10%.  Negative values count from the end of the disk.  For example, -1s specifies exactly the last sector.
        
        'mkpart' makes a partition without creating a new file system on the partition.  FS-TYPE may be specified to set an appropriate partition ID.
(parted) mkpart primary fat32 2048s 206848s
(parted) mkpart primary ext4 208896s -1s
(parted) print                                                            
Model: MXT-USB Storage Device (scsi)
Disk /dev/sdd: 31.9GB
Sector size (logical/physical): 512B/512B
Partition Table: msdos
Disk Flags: 

Number  Start   End     Size    Type     File system  Flags
 1      1049kB  106MB   105MB   primary  fat32        lba
 2      107MB   31.9GB  31.8GB  primary  ext4         lba

(parted) set 1 boot on                                                    
(parted) print                                                            
Model: MXT-USB Storage Device (scsi)
Disk /dev/sdd: 31.9GB
Sector size (logical/physical): 512B/512B
Partition Table: msdos
Disk Flags: 

Number  Start   End     Size    Type     File system  Flags
 1      1049kB  106MB   105MB   primary  fat32        boot, lba
 2      107MB   31.9GB  31.8GB  primary  ext4         lba

(parted) quit                                                             
Information: You may need to update /etc/fstab.

balakumaran@balakumaran-USB:~/Desktop/RPi/linux_build$ sudo fdisk -l /dev/sdd
Disk /dev/sdd: 29.7 GiB, 31914983424 bytes, 62333952 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0xcde890ba

Device     Boot  Start      End  Sectors  Size Id Type
/dev/sdd1  *      2048   206848   204801  100M  c W95 FAT32 (LBA)
/dev/sdd2       208896 62333951 62125056 29.6G 83 Linux
balakumaran@balakumaran-USB:~/Desktop/RPi/linux_build$

Copy firmware and kernel to boot partition.

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kaba@kaba-Vostro-1550:~/Desktop/kernel/vanila_kernel
$ sudo mount /dev/sdb1 /mnt/boot/
kaba@kaba-Vostro-1550:~/Desktop/kernel/vanila_kernel
$ sudo cp ../kernel_out/arch/arm64/boot/Image /mnt/boot/kernel8.img
[sudo] password for kaba: 
kaba@kaba-Vostro-1550:~/Desktop/kernel/vanila_kernel
$ sudo cp ../firmware/* /mnt/boot/
kaba@kaba-Vostro-1550:~/Desktop/kernel/vanila_kernel
$

Install device-tree blobs from Raspberry Pi repo into boot partition. The device-tree in upstream kernel is not working for some reason. I couldn’t get more information regarding that.

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kaba@kaba-Vostro-1550:~/Desktop/kernel/rpi_kernel
$ make O=../rpi_out ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- bcmrpi3_defconfig
kaba@kaba-Vostro-1550:~/Desktop/kernel/rpi_kernel
$ sudo make O=../rpi_out ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- INSTALL_PATH=/mnt/boot/ dtbs_install

Copy rootfs into second partition. Also install kernel modules into that.

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kaba@kaba-Vostro-1550:~/Desktop/kernel/vanila_kernel
$ sudo mount /dev/sdb2 /mnt/rootfs/
kaba@kaba-Vostro-1550:~/Desktop/kernel/vanila_kernel
$ sudo cp -rf ../rootfs/* /mnt/rootfs/
kaba@kaba-Vostro-1550:~/Desktop/kernel/vanila_kernel
$ sudo make O=../kernel_out ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- INSTALL_MOD_PATH=/mnt/rootfs/ modules_install
kaba@kaba-Vostro-1550:~/Desktop/kernel/vanila_kernel
$ sync

Create config.txt and cmdline.txt as follows. Make sure you update device-tree and overlay_prefix based on your configuration.

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kaba@kaba-Vostro-1550:/mnt/boot
$ cat cmdline.txt 
dwc_otg.lpm_enable=0 console=serial0,115200 root=/dev/mmcblk0p2 rootfstype=ext4 rootwait    
kaba@kaba-Vostro-1550:/mnt/boot
$ cat config.txt 
dtoverlay=vc4-fkms-v3d,cma-256
disable_overscan=1
dtparam=audio=on
device_tree=dtbs/4.19.0-rc5-v8+/broadcom/bcm2710-rpi-3-b.dtb
overlay_prefix=dtbs/4.19.0-rc5-v8+/overlays/
enable_uart=1
kaba@kaba-Vostro-1550:/mnt/boot
$

Put the SD card in Raspberry Pi 3 and boot.