From a5bde5d8fde8a8cb28e59a672d5ddc5b9c1e7656 Mon Sep 17 00:00:00 2001 From: Breno Leitao Date: Wed, 5 Aug 2026 07:52:36 -0700 Subject: workqueue: skip the node_nr_active update for non-unbound workqueues apply_wqattrs_commit() updates node_nr_active->max unconditionally. wq->node_nr_active[] is only allocated for unbound workqueues, so guard the call before per-cpu workqueues start using this path. No functional change: only unbound workqueues reach apply_wqattrs_*() today. Signed-off-by: Breno Leitao Signed-off-by: Tejun Heo --- Documentation/arch/arc/arc.rst | 85 +++++++++++++++++++++++++++++++++++++ Documentation/arch/arc/features.rst | 3 ++ Documentation/arch/arc/index.rst | 10 +++++ 3 files changed, 98 insertions(+) create mode 100644 Documentation/arch/arc/arc.rst create mode 100644 Documentation/arch/arc/features.rst create mode 100644 Documentation/arch/arc/index.rst (limited to 'Documentation/arch/arc') diff --git a/Documentation/arch/arc/arc.rst b/Documentation/arch/arc/arc.rst new file mode 100644 index 000000000..5923dee37 --- /dev/null +++ b/Documentation/arch/arc/arc.rst @@ -0,0 +1,85 @@ +.. SPDX-License-Identifier: GPL-2.0 + +Linux kernel for ARC processors +******************************* + +Other sources of information +############################ + +Below are some resources where more information can be found on +ARC processors and relevant open source projects. + +- ``_ - Community portal for open source on ARC. + Good place to start to find relevant FOSS projects, toolchain releases, + news items and more. + +- ``_ - + Home for all development activities regarding open source projects for + ARC processors. Some of the projects are forks of various upstream projects, + where "work in progress" is hosted prior to submission to upstream projects. + Other projects are developed by Synopsys and made available to community + as open source for use on ARC Processors. + +- `Official Synopsys ARC Processors website + `_ - + location, with access to some IP documentation (`Programmer's Reference + Manual, AKA PRM for ARC HS processors + `_) + and free versions of some commercial tools (`Free nSIM + `_ and + `MetaWare Light Edition `_). + Please note though, registration is required to access both the documentation and + the tools. + +Important note on ARC processors configurability +################################################ + +ARC processors are highly configurable and several configurable options +are supported in Linux. Some options are transparent to software +(e.g., cache geometries), some can be detected at runtime and configured +and used accordingly, while some need to be explicitly selected or configured +in the kernel's configuration utility (AKA "make menuconfig"). + +However not all configurable options are supported when an ARC processor +is to run Linux. SoC design teams should refer to "Appendix E: +Configuration for ARC Linux" in the ARC HS Databook for configurability +guidelines. + +Following these guidelines and selecting valid configuration options +up front is critical to help prevent any unwanted issues during +SoC bringup and software development in general. + +Building the Linux kernel for ARC processors +############################################ + +The process of kernel building for ARC processors is the same as for any other +architecture and could be done in 2 ways: + +- Cross-compilation: process of compiling for ARC targets on a development + host with a different processor architecture (generally x86_64/amd64). +- Native compilation: process of compiling for ARC on a ARC platform + (hardware board or a simulator like QEMU) with complete development environment + (GNU toolchain, dtc, make etc) installed on the platform. + +In both cases, up-to-date GNU toolchain for ARC for the host is needed. +Synopsys offers prebuilt toolchain releases which can be used for this purpose, +available from: + +- Synopsys GNU toolchain releases: + ``_ + +- Linux kernel compilers collection: + ``_ + +- Bootlin's toolchain collection: ``_ + +Once the toolchain is installed in the system, make sure its "bin" folder +is added in your ``PATH`` environment variable. Then set ``ARCH=arc`` & +``CROSS_COMPILE=arc-linux`` (or whatever matches installed ARC toolchain prefix) +and then as usual ``make defconfig && make``. + +This will produce "vmlinux" file in the root of the kernel source tree +usable for loading on the target system via JTAG. +If you need to get an image usable with U-Boot bootloader, +type ``make uImage`` and ``uImage`` will be produced in ``arch/arc/boot`` +folder. diff --git a/Documentation/arch/arc/features.rst b/Documentation/arch/arc/features.rst new file mode 100644 index 000000000..49ff446ff --- /dev/null +++ b/Documentation/arch/arc/features.rst @@ -0,0 +1,3 @@ +.. SPDX-License-Identifier: GPL-2.0 + +.. kernel-feat:: features arc diff --git a/Documentation/arch/arc/index.rst b/Documentation/arch/arc/index.rst new file mode 100644 index 000000000..10bf8c270 --- /dev/null +++ b/Documentation/arch/arc/index.rst @@ -0,0 +1,10 @@ +=================== +ARC architecture +=================== + +.. toctree:: + :maxdepth: 1 + + arc + + features -- cgit v1.3.1