| 5.1. Booting the Installer on 64-bit ARM | ||
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Chapter 5. Booting the Installation System | 
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| 5.1. Booting the Installer on 64-bit ARM | ||
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Chapter 5. Booting the Installation System |
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The graphical installer is not enabled on the arm64 debian-installer images
for 20.04 so the serial console is used. The console device
should be detected automatically from the firmware, but if it is
not then after you boot linux from the GRUB menu you will see a
“Booting Linux” message, then nothing more.
If you hit this issue you will need to set a specific console
config on the kernel command line. Hit e
for “Edit Kernel command-line” at the GRUB menu, and change
--- quiet
to
console=<device>,<speed>
e.g.
console=ttyAMA0,115200n8
. When finished hit Control+x to continue booting with new setting.
Juno has UEFI so the install is straightforward. The most practical method is installing from USB stick. You need up to date firmware for USB-booting to work. Builds from http://releases.linaro.org/latest/members/arm/ after March 2015 tested OK. Consult Juno documentation on firmware updating.
Prepare a standard arm64 CD image on a USB stick. Insert it in one of the USB ports on the back. Plug a serial cable into the upper 9-pin serial port on the back. If you need networking (netboot image) plug the ethernet cable into the socket on the front of the machine.
Run a serial console at 115200, 8bit no parity, and boot the Juno. It should boot from the USB stick to a GRUB menu. The console config is not correctly detected on Juno so just hitting return will show no kernel output. Set the console to
console=ttyAMA0,115200n8
as described in (Section 5.1.1, “Console configuration”). Control+x to boot should show you the debian-installer screens,
and allow you to proceed with a standard installation.
UEFI is available for this machine but it is normally shipped with U-Boot so you will need to either install UEFI firmware first then use standard boot/install methods, or use U-Boot boot methods. Also USB is not supported in the jessie kernel so installing from a USB stick does not work. You must use a serial console to control the installation because the graphical installer is not enabled on the arm64 architecture.
The recommended install method is to copy the debian-installer kernel and
initrd onto the hard drive, using the openembedded system
supplied with the machine, then boot from that to run the
installer. Alternatively use TFTP to get the kernel/dtb/initrd
copied over and booted (Section 5.1.4.1, “TFTP-booting in U-Boot”). After
installation, manual changes to boot from the installed image
are needed.
Run a serial console at 115200, 8bit no parity, and boot the machine. Reboot the machine and when you see “Hit any key to stop autoboot:” hit a key to get a Mustang# prompt. Then use U-Boot commands to load and boot the kernel, dtb and initrd.
Booting from the network requires that you have a network connection and a TFTP network boot server (and probably also a DHCP, RARP, or BOOTP server for automatic network configuration).
The server-side setup to support network booting is described in Section 4.3, “Preparing Files for TFTP Net Booting”.
Network booting on systems using the U-Boot firmware consists of three steps: a) configuring the network, b) loading the images (kernel/initial ramdisk/dtb) into memory and c) actually executing the previosly loaded code.
First you have to configure the network, either automatically via DHCP by running
setenv autoload no dhcp
or manually by setting several environment variables
setenv ipaddr <ip address of the client> setenv netmask <netmask> setenv serverip <ip address of the tftp server> setenv dnsip <ip address of the nameserver> setenv gatewayip <ip address of the default gateway>
If you prefer, you can make these settings permanent by running
saveenv
Afterwards you need to load the images (kernel/initial ramdisk/dtb) into memory. This is done with the tftpboot command, which has to be provided with the address at which the image shall be stored in memory. Unfortunately the memory map can vary from system to system, so there is no general rule which addresses can be used for this.
On some systems, U-Boot predefines a set of environment variables with suitable load addresses: kernel_addr_r, ramdisk_addr_r and fdt_addr_r. You can check whether they are defined by running
printenv kernel_addr_r ramdisk_addr_r fdt_addr_r
If they are not defined, you have to check your system's documentation for appropriate values and set them manually. For systems based on Allwinner SunXi SOCs (e.g. the Allwinner A10, architecture name “sun4i” or the Allwinner A20, architecture name “sun7i”), you can e.g. use the follwing values:
setenv kernel_addr_r 0x46000000 setenv fdt_addr_r 0x47000000 setenv ramdisk_addr_r 0x48000000
When the load addresses are defined, you can load the images into memory from the previously defined tftp server with
tftpboot ${kernel_addr_r} <filename of the kernel image>
tftpboot ${fdt_addr_r} <filename of the dtb>
tftpboot ${ramdisk_addr_r} <filename of the initial ramdisk image>
The third part is setting the kernel commandline and actually executing the loaded code. U-Boot passes the content of the “bootargs” environment variable as commandline to the kernel, so any parameters for the kernel and the installer - such as the console device (see Section 5.3.1, “Boot console”) or preseeding options (see Section 5.3.2, “Ubuntu Installer Parameters” and Appendix B, Automating the installation using preseeding) - can be set with a command like
setenv bootargs console=ttyS0,115200 rootwait panic=10
The exact command to execute the previously loaded code depends on the image format used. With uImage/uInitrd, the command is
bootm ${kernel_addr_r} ${ramdisk_addr_r} ${fdt_addr_r}
and with native Linux images it is
bootz ${kernel_addr_r} ${ramdisk_addr_r}:${filesize} ${fdt_addr_r}
Note: When booting standard linux images, it is important to load the initial ramdisk image after the kernel and the dtb as U-Boot sets the filesize variable to the size of the last file loaded and the bootz command requires the size of the ramdisk image to work correctly. In case of booting a platform-specific kernel, i.e. a kernel without device-tree, simply omit the ${fdt_addr_r} parameter.
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| Chapter 5. Booting the Installation System |  |
5.2. Accessibility |