arc.rst (3898B)
1.. SPDX-License-Identifier: GPL-2.0 2 3Linux kernel for ARC processors 4******************************* 5 6Other sources of information 7############################ 8 9Below are some resources where more information can be found on 10ARC processors and relevant open source projects. 11 12- `<https://embarc.org>`_ - Community portal for open source on ARC. 13 Good place to start to find relevant FOSS projects, toolchain releases, 14 news items and more. 15 16- `<https://github.com/foss-for-synopsys-dwc-arc-processors>`_ - 17 Home for all development activities regarding open source projects for 18 ARC processors. Some of the projects are forks of various upstream projects, 19 where "work in progress" is hosted prior to submission to upstream projects. 20 Other projects are developed by Synopsys and made available to community 21 as open source for use on ARC Processors. 22 23- `Official Synopsys ARC Processors website 24 <https://www.synopsys.com/designware-ip/processor-solutions.html>`_ - 25 location, with access to some IP documentation (`Programmer's Reference 26 Manual, AKA PRM for ARC HS processors 27 <https://www.synopsys.com/dw/doc.php/ds/cc/programmers-reference-manual-ARC-HS.pdf>`_) 28 and free versions of some commercial tools (`Free nSIM 29 <https://www.synopsys.com/cgi-bin/dwarcnsim/req1.cgi>`_ and 30 `MetaWare Light Edition <https://www.synopsys.com/cgi-bin/arcmwtk_lite/reg1.cgi>`_). 31 Please note though, registration is required to access both the documentation and 32 the tools. 33 34Important note on ARC processors configurability 35################################################ 36 37ARC processors are highly configurable and several configurable options 38are supported in Linux. Some options are transparent to software 39(i.e cache geometries, some can be detected at runtime and configured 40and used accordingly, while some need to be explicitly selected or configured 41in the kernel's configuration utility (AKA "make menuconfig"). 42 43However not all configurable options are supported when an ARC processor 44is to run Linux. SoC design teams should refer to "Appendix E: 45Configuration for ARC Linux" in the ARC HS Databook for configurability 46guidelines. 47 48Following these guidelines and selecting valid configuration options 49up front is critical to help prevent any unwanted issues during 50SoC bringup and software development in general. 51 52Building the Linux kernel for ARC processors 53############################################ 54 55The process of kernel building for ARC processors is the same as for any other 56architecture and could be done in 2 ways: 57 58- Cross-compilation: process of compiling for ARC targets on a development 59 host with a different processor architecture (generally x86_64/amd64). 60- Native compilation: process of compiling for ARC on a ARC platform 61 (hardware board or a simulator like QEMU) with complete development environment 62 (GNU toolchain, dtc, make etc) installed on the platform. 63 64In both cases, up-to-date GNU toolchain for ARC for the host is needed. 65Synopsys offers prebuilt toolchain releases which can be used for this purpose, 66available from: 67 68- Synopsys GNU toolchain releases: 69 `<https://github.com/foss-for-synopsys-dwc-arc-processors/toolchain/releases>`_ 70 71- Linux kernel compilers collection: 72 `<https://mirrors.edge.kernel.org/pub/tools/crosstool>`_ 73 74- Bootlin's toolchain collection: `<https://toolchains.bootlin.com>`_ 75 76Once the toolchain is installed in the system, make sure its "bin" folder 77is added in your ``PATH`` environment variable. Then set ``ARCH=arc`` & 78``CROSS_COMPILE=arc-linux`` (or whatever matches installed ARC toolchain prefix) 79and then as usual ``make defconfig && make``. 80 81This will produce "vmlinux" file in the root of the kernel source tree 82usable for loading on the target system via JTAG. 83If you need to get an image usable with U-Boot bootloader, 84type ``make uImage`` and ``uImage`` will be produced in ``arch/arc/boot`` 85folder.