ARM systems are much more heterogenous than the i386/amd64-based PC architecture, so whilst 64-bit ARM machines should boot in a standardised way, like PCs, the situation is more complicated for 32-bit ARM machines. The ARM architecture is used mainly in so-called systems-on-chip (SoCs). These SoCs are designed by many different companies with vastly varying hardware components even for the very basic functionality required to bring the system up. System firmware interfaces have been increasingly standardised over time, but especially on older hardware firmware/boot interfaces vary a great deal, so on these systems the Linux kernel has to take care of many system-specific low-level issues which are handled by the mainboard's BIOS in the PC world. At the beginning of the ARM support in the Linux kernel, the hardware variety resulted in the requirement of having a separate kernel for each ARM system in contrast to the one-fits-all kernel for PC systems. As this approach does not scale to a large number of different systems, work was done to allow booting with a single ARM kernel that can run on different ARM systems. Support for newer ARM systems gets implemented in a way that allows the use of such a multiplatform kernel, but for several older systems a seperate specific kernel is still required. Because of this, the standard &debian; distribution only supports installation on a selected number of older 32-bit ARM systems in addition to the newer (32 and 64-bit) systems which are supported by the ARM multiplatform kernels (called 'armmp' on 32-bit armhf, no flavour name on 64-bit arm64). The ARM architecture has evolved over time and modern ARM processors provide features which are not available in older models. &debian; therefore provides three ARM ports: the &debian;/arm64 port for all 64-bit machines, and the &debian;/armel and the &debian;/armhf ports for 32-bit machines. &debian;/armel targets older ARM processors without support for a hardware floating point unit (FPU), while &debian;/armhf works only on newer ARM processors which implement at least the ARMv7 architecture with version 3 of the ARM vector floating point specification (VFPv3). &debian;/armhf makes use of the extended features and performance enhancements available on these models. &debian;/arm64 works on processors which implement at least the ARMv8 architecture (which is 64bit). Technically, all currently available ARM CPUs can be run in either endian mode (big or little), but in practice the vast majority use little-endian mode. All of &debian;/arm64, &debian;/armhf and &debian;/armel support only little-endian systems. Arm64/AArch64/ARMv8 hardware became available quite late in the &debian; &releasename-cap; release cycle so not many platforms have had support merged in the mainline kernel version in this release, which is the main requirement to have &d-i; working on them. The tested platforms are listed below, but in general, the multiplatform support in the arm64 Linux kernel allows running &d-i; on arm64 systems not explicitly listed below, so long as the kernel used by &d-i; has support for the target system's components and a device-tree file for the target is available. In these cases, the installer can usually provide a working userland installation, and so long as UEFI is in use, it should be able to make the system bootable as well. If UEFI is not used (some 64-bit machines have been shipped with uboot) it will not be able to make the system bootable. The following platforms are known to be supported by &debian;/arm64 in this release. There is only one kernel, which supports all platforms. Applied Micro (APM) Mustang/X-gene The APM Mustang was the first linux-capable ARMv8 system available. It uses the X-gene soc, since also used in other machines, which is an 8-core 16GB device, with ethernet, USB, serial. The form-factor is a desktop PC box. All the hardware is supported in the mainline kernel. ARM Juno Development Platform Juno is a capable development board with a 6-core (2xA57, 4xA53) ARMv8-A 800Mhz CPU, Mali (T624) graphics, 8GB DDR3 RAM, Ethernet, USB, Serial. It was designed for system bringup and power testing so is neither small nor cheap, but was one of the first boards available. All the hardware is supported in the mainline kernel. When using &d-i; on non-UEFI systems, you will have to manually make the system bootable at the end of the installation, e.g. by running the required commands in a shell started from within &d-i;. The following systems are known to work with &debian;/armhf using the multiplatform (armmp) kernel: Freescale MX53 Quick Start Board The IMX53QSB is a development board based on the i.MX53 SoC. Versatile Express The Versatile Express is a development board series from ARM consisting of a baseboard which can be equipped with various CPU daughterboards. Certain Allwinner sunXi-based development boards and embedded systems The armmp kernel supports several development boards and embedded systems based on the Allwinner A10 (architecture codename sun4i), A10s/A13 (architecture codename sun5i) and A20 (architecture codename sun7i) SoCs. Full installer support is currently available for the following sunXi-based systems: Cubietech Cubieboard 1 + 2 / Cubietruck LeMaker Banana Pi and Banana Pro LinkSprite pcDuino and pcDuino3 Mele A1000 Miniand Hackberry Olimex A10-Olinuxino-LIME / A10s-Olinuxino Micro / A13-Olinuxino / A13-Olinuxino Micro / A20-Olinuxino-LIME / A20-Olinuxino-LIME2 / A20-Olinuxino Micro PineRiver Mini X-Plus System support for Allwinner sunXi-based devices is limited to drivers and device-tree information available in the mainline Linux kernel. The android-derived linux-sunxi.org 3.4 kernel series is not supported by Debian. The mainline Linux kernel generally supports serial console, ethernet, SATA, USB and MMC/SD-cards on Allwinner A10, A10s/A13 and A20 SoCs, but it does not have native drivers for the display (HDMI/VGA/LCD) and audio hardware in these SoCs. The NAND flash memory that is built into some sunXi-based systems is not supported. Using a local display is technically possible without native display drivers via the simplefb infrastructure in the mainline kernel, which relies on the u-boot bootloader for initializing the display hardware, but this is not supported by the u-boot version in &debian; 8. SolidRun Cubox-i2eX / Cubox-i4Pro The Cubox-i series is a set of small, cubical-shaped systems based on the Freescale i.MX6 SoC family. System support for the Cubox-i series is limited to drivers and device-tree information available in the mainline Linux kernel; the Freescale 3.0 kernel series for the Cubox-i is not supported by Debian. Available drivers in the mainline kernel include serial console, ethernet, USB, MMC/SD-card and display support over HDMI (console and X11). In addition to that, the eSATA port on the Cubox-i4Pro is supported. Wandboard Quad The Wandboard Quad is a development board based on the Freescale i.MX6 Quad SoC. System support for it is limited to drivers and device-tree information available in the mainline Linux kernel; the wandboard-specific 3.0 and 3.10 kernel series from wandboard.org are not supported by Debian. The mainline kernel includes driver support for serial console, display via HDMI (console and X11), ethernet, USB, MMC/SD and SATA. Support for the onboard audio options (analog, S/PDIF, HDMI-Audio) and for the onboard WLAN/Bluetooth module is not available in &debian; 8. Generally, the ARM multiplatform support in the Linux kernel allows running &d-i; on armhf systems not explicitly listed above, as long as the kernel used by &d-i; has support for the target system's components and a device-tree file for the target is available. In these cases, the installer can usually provide a working userland installation, but it probably cannot automatically make the system bootable, as doing that in many cases requires device-specific information. When using &d-i; on such systems, you have to manually make the system bootable at the end of the installation, e.g. by running the required commands in a shell started from within &d-i;. EfikaMX The EfikaMX platform (Genesi Efika Smartbook and Genesi EfikaMX nettop) has been supported in &debian; 7 with a platform-specific kernel, but is not supported anymore from &debian; 8 onwards. The code required to build the formerly used platform-specific kernel has been removed from the upstream Linux kernel source in 2012, so Debian cannot provide newer builds. Using the armmp multiplatform kernel on the EfikaMX platform would require device-tree support for it, which is currently not available. The following platforms are supported by &debian;/armel; they require platform-specific kernels. IXP4xx The Intel IXP4xx processor series is used in network attached storage devices like the Linksys NSLU2. While there is kernel support for this platform in &debian; 8, it is not supported by the &d-i;. It is possible to do a dist-upgrade from Debian 7 to Debian 8 for existing installations, though. Due to the low amount of RAM that systems based on the IXP4xx usually have, this requires that swap space is enabled prior to upgrading. Support for the IXP4xx platform will be dropped completely in &debian; 9. Kirkwood Kirkwood is a system on a chip (SoC) from Marvell that integrates an ARM CPU, Ethernet, SATA, USB, and other functionality in one chip. We currently support the following Kirkwood based devices: OpenRD (OpenRD-Base, OpenRD-Client and OpenRD-Ultimate), plug computers (SheevaPlug, GuruPlug and DreamPlug), QNAP Turbo Station (all TS-11x, TS-21x and TS-41x models), and LaCie NASes (Network Space v2, Network Space Max v2, Internet Space v2, d2 Network v2, 2Big Network v2 and 5Big Network v2). Orion5x Orion is a system on a chip (SoC) from Marvell that integrates an ARM CPU, Ethernet, SATA, USB, and other functionality in one chip. There are many Network Attached Storage (NAS) devices on the market that are based on an Orion chip. We currently support the following Orion based devices: Buffalo Kurobox, D-Link DNS-323 and HP mv2120. Versatile The Versatile platform is emulated by QEMU and is therefore a nice way to test and run &debian; on ARM if you don't have the hardware. IOP32x Intel's I/O Processor (IOP) line is found in a number of products related to data storage and processing, such as the GLAN Tank from IO-Data and the Thecus N2100. &debian; has supported the IOP32x platform in &debian; 7, but does not support it anymore from version 8 on due to hardware constraints of the platform which make it unsuitable for the installation of newer &debian; releases. MV78xx0 The MV78xx0 platform has been used on the Marvell DB-78xx0-BP development board. It was supported in Debian 7 with a platform-specific kernel (based on the Linux kernel version 3.2), but is not supported anymore from Debian 8 onwards.