Linux kernel ============ The Linux kernel is the core of any Linux operating system. It manages hardware, system resources, and provides the fundamental services for all other software. Quick Start ----------- * Report a bug: See Documentation/admin-guide/reporting-issues.rst * Get the latest kernel: https://kernel.org * Build the kernel: See Documentation/admin-guide/quickly-build-trimmed-linux.rst * Join the community: https://lore.kernel.org/ Essential Documentation ----------------------- All users should be familiar with: * Building requirements: Documentation/process/changes.rst * Code of Conduct: Documentation/process/code-of-conduct.rst * License: See COPYING Documentation can be built with make htmldocs or viewed online at: https://www.kernel.org/doc/html/latest/ Who Are You? ============ Find your role below: * New Kernel Developer - Getting started with kernel development * Academic Researcher - Studying kernel internals and architecture * Security Expert - Hardening and vulnerability analysis * Backport/Maintenance Engineer - Maintaining stable kernels * System Administrator - Configuring and troubleshooting * Maintainer - Leading subsystems and reviewing patches * Hardware Vendor - Writing drivers for new hardware * Distribution Maintainer - Packaging kernels for distros * AI Coding Assistant - LLMs and AI-powered development tools For Specific Users ================== New Kernel Developer -------------------- Welcome! Start your kernel development journey here: * Getting Started: Documentation/process/development-process.rst * Your First Patch: Documentation/process/submitting-patches.rst * Coding Style: Documentation/process/coding-style.rst * Build System: Documentation/kbuild/index.rst * Development Tools: Documentation/dev-tools/index.rst * Kernel Hacking Guide: Documentation/kernel-hacking/hacking.rst * Core APIs: Documentation/core-api/index.rst Academic Researcher ------------------- Explore the kernel's architecture and internals: * Researcher Guidelines: Documentation/process/researcher-guidelines.rst * Memory Management: Documentation/mm/index.rst * Scheduler: Documentation/scheduler/index.rst * Networking Stack: Documentation/networking/index.rst * Filesystems: Documentation/filesystems/index.rst * RCU (Read-Copy Update): Documentation/RCU/index.rst * Locking Primitives: Documentation/locking/index.rst * Power Management: Documentation/power/index.rst Security Expert --------------- Security documentation and hardening guides: * Security Documentation: Documentation/security/index.rst * LSM Development: Documentation/security/lsm-development.rst * Self Protection: Documentation/security/self-protection.rst * Reporting Vulnerabilities: Documentation/process/security-bugs.rst * CVE Procedures: Documentation/process/cve.rst * Embargoed Hardware Issues: Documentation/process/embargoed-hardware-issues.rst * Security Features: Documentation/userspace-api/seccomp_filter.rst Backport/Maintenance Engineer ----------------------------- Maintain and stabilize kernel versions: * Stable Kernel Rules: Documentation/process/stable-kernel-rules.rst * Backporting Guide: Documentation/process/backporting.rst * Applying Patches: Documentation/process/applying-patches.rst * Subsystem Profile: Documentation/maintainer/maintainer-entry-profile.rst * Git for Maintainers: Documentation/maintainer/configure-git.rst System Administrator -------------------- Configure, tune, and troubleshoot Linux systems: * Admin Guide: Documentation/admin-guide/index.rst * Kernel Parameters: Documentation/admin-guide/kernel-parameters.rst * Sysctl Tuning: Documentation/admin-guide/sysctl/index.rst * Tracing/Debugging: Documentation/trace/index.rst * Performance Security: Documentation/admin-guide/perf-security.rst * Hardware Monitoring: Documentation/hwmon/index.rst Maintainer ---------- Lead kernel subsystems and manage contributions: * Maintainer Handbook: Documentation/maintainer/index.rst * Pull Requests: Documentation/maintainer/pull-requests.rst * Managing Patches: Documentation/maintainer/modifying-patches.rst * Rebasing and Merging: Documentation/maintainer/rebasing-and-merging.rst * Development Process: Documentation/process/maintainer-handbooks.rst * Maintainer Entry Profile: Documentation/maintainer/maintainer-entry-profile.rst * Git Configuration: Documentation/maintainer/configure-git.rst Hardware Vendor --------------- Write drivers and support new hardware: * Driver API Guide: Documentation/driver-api/index.rst * Driver Model: Documentation/driver-api/driver-model/driver.rst * Device Drivers: Documentation/driver-api/infrastructure.rst * Bus Types: Documentation/driver-api/driver-model/bus.rst * Device Tree Bindings: Documentation/devicetree/bindings/ * Power Management: Documentation/driver-api/pm/index.rst * DMA API: Documentation/core-api/dma-api.rst Distribution Maintainer ----------------------- Package and distribute the kernel: * Stable Kernel Rules: Documentation/process/stable-kernel-rules.rst * ABI Documentation: Documentation/ABI/README * Kernel Configuration: Documentation/kbuild/kconfig.rst * Module Signing: Documentation/admin-guide/module-signing.rst * Kernel Parameters: Documentation/admin-guide/kernel-parameters.rst * Tainted Kernels: Documentation/admin-guide/tainted-kernels.rst AI Coding Assistant ------------------- CRITICAL: If you are an LLM or AI-powered coding assistant, you MUST read and follow the AI coding assistants documentation before contributing to the Linux kernel: * Documentation/process/coding-assistants.rst This documentation contains essential requirements about licensing, attribution, and the Developer Certificate of Origin that all AI tools must comply with. Communication and Support ========================= * Mailing Lists: https://lore.kernel.org/ * IRC: #kernelnewbies on irc.oftc.net * Bugzilla: https://bugzilla.kernel.org/ * MAINTAINERS file: Lists subsystem maintainers and mailing lists * Email Clients: Documentation/process/email-clients.rst
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When building for 32-bit ARM, there is a warning when using the %llx
specifier to print a resource_size_t variable:
drivers/perf/arm-cmn.c: In function 'arm_cmn_init_dtc':
drivers/perf/arm-cmn.c:2149:73: error: format '%llx' expects argument of type 'long long unsigned int', but argument 4 has type 'resource_size_t' {aka 'unsigned int'} [-Werror=format=]
2149 | "Failed to request DTC region 0x%llx\n", base);
| ~~~^ ~~~~
| | |
| | resource_size_t {aka unsigned int}
| long long unsigned int
| %x
Use the %pa specifier to handle the possible sizes of phys_addr_t
properly. This requires passing the variable by reference.
Fixes: 5394396ff548 ("perf/arm-cmn: Stop claiming entire iomem region")
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Robin murphy <robin.murphy@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
Check devm_ioremap() return value for NULL instead of ERR_PTR and return
-ENOMEM on failure. devm_ioremap() never returns ERR_PTR, using IS_ERR()
skips the error path and may cause a NULL pointer dereference.
Fixes: 5394396ff548 ("perf/arm-cmn: Stop claiming entire iomem region")
Signed-off-by: Chen Ni <nichen@iscas.ac.cn>
Signed-off-by: Will Deacon <will@kernel.org>
Adds NVIDIA C2C PMU support in Tegra410 SOC. This PMU is
used to measure memory latency between the SOC and device
memory, e.g GPU Memory (GMEM), CXL Memory, or memory on
remote Tegra410 SOC.
Reviewed-by: Ilkka Koskinen <ilkka@os.amperecomputing.com>
Signed-off-by: Besar Wicaksono <bwicaksono@nvidia.com>
Signed-off-by: Will Deacon <will@kernel.org>
Adds CPU Memory (CMEM) Latency PMU support in Tegra410 SOC.
The PMU is used to measure latency between the edge of the
Unified Coherence Fabric to the local system DRAM.
Reviewed-by: Ilkka Koskinen <ilkka@os.amperecomputing.com>
Signed-off-by: Besar Wicaksono <bwicaksono@nvidia.com>
Signed-off-by: Will Deacon <will@kernel.org>
Adds PCIE-TGT PMU support in Tegra410 SOC. This PMU is
instanced in each root complex in the SOC and it captures
traffic originating from any source towards PCIE BAR and CXL
HDM range. The traffic can be filtered based on the
destination root port or target address range.
Reviewed-by: Ilkka Koskinen <ilkka@os.amperecomputing.com>
Signed-off-by: Besar Wicaksono <bwicaksono@nvidia.com>
Signed-off-by: Will Deacon <will@kernel.org>
Adds PCIE PMU support in Tegra410 SOC. This PMU is instanced
in each root complex in the SOC and can capture traffic from
PCIE device to various memory types. This PMU can filter traffic
based on the originating root port or BDF and the target memory
types (CPU DRAM, GPU Memory, CXL Memory, or remote Memory).
Reviewed-by: Ilkka Koskinen <ilkka@os.amperecomputing.com>
Signed-off-by: Besar Wicaksono <bwicaksono@nvidia.com>
Signed-off-by: Will Deacon <will@kernel.org>
Add interface to get ACPI device associated with the
PMU. This ACPI device may contain additional properties
not covered by the standard properties.
Reviewed-by: Ilkka Koskinen <ilkka@os.amperecomputing.com>
Signed-off-by: Besar Wicaksono <bwicaksono@nvidia.com>
Signed-off-by: Will Deacon <will@kernel.org>
The Unified Coherence Fabric (UCF) contains last level cache
and cache coherent interconnect in Tegra410 SOC. The PMU in
this device can be used to capture events related to access
to the last level cache and memory from different sources.
Reviewed-by: Ilkka Koskinen <ilkka@os.amperecomputing.com>
Signed-off-by: Besar Wicaksono <bwicaksono@nvidia.com>
Signed-off-by: Will Deacon <will@kernel.org>
The documentation in nvidia-pmu.rst contains PMUs specific
to NVIDIA Tegra241 SoC. Rename the file for this specific
SoC to have better distinction with other NVIDIA SoC.
Signed-off-by: Besar Wicaksono <bwicaksono@nvidia.com>
Signed-off-by: Will Deacon <will@kernel.org>
So far, the PMU has been the only thing of interest in the vast mass
of CMN registers, so we've gotten away with simply claiming the entire
iomem region. However, now that we can support other features like MPAM
controllers for the system caches, the PMU driver needs to stop being
selfish and learn to share. Similarly to arm-ni, requesting just the
DTC node(s) should suffice for staking our exclusive claim to the PMU
features, as requesting hundreds of tiny regions for all the individual
pmu_event_sel registers is definitely not worth the considerable bother.
As a consequence, we can also streamline the annoying CMN-600 special
cases even more. The ACPI binding has in fact always specified a strict
order for all resources, so we can reasonably drop the ancient pretence
of swapping base and cfg, which IIRC was more just a moment of doubt on
my part than anything else.
Cc: James Morse <james.morse@arm.com>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Tested-by: Ben Horgan <ben.horgan@arm.com>
Reviewed-by: Ilkka Koskinen <ilkka@os.amperecomputing.com>
Signed-off-by: Will Deacon <will@kernel.org>
Other places that are doing this version comparison are already using
pmuv3_implemented(), so might as well use it here too for consistency.
Signed-off-by: James Clark <james.clark@linaro.org>
Reviewed-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Colton Lewis <coltonlewis@google.com>
Signed-off-by: Will Deacon <will@kernel.org>
On the host, this change doesn't make a difference because the fields
are defined as FTR_EXACT. However, KVM allows userspace to set these
fields for a guest and overrides the type to be FTR_LOWER_SAFE. And
while KVM used to do an unsigned comparison to validate that the new
value is lower than what the hardware provides, since the linked commit
it uses the generic sanitization framework which does a signed
comparison.
Fix it by defining these fields as unsigned. In theory, without this
fix, userspace could set a higher PMU version than the hardware supports
by providing any value with the top bit set.
Fixes: c118cead07a7 ("KVM: arm64: Use generic sanitisation for ID_(AA64)DFR0_EL1")
Signed-off-by: James Clark <james.clark@linaro.org>
Reviewed-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Colton Lewis <coltonlewis@google.com>
Signed-off-by: Will Deacon <will@kernel.org>
ID_AA64DFR0_EL1.PMUVer is an unsigned field, so this skips
initialization of host_data_ptr(nr_event_counters) for PMUv3 for Armv8.8
onwards as they appear as negative values.
Fix it by reading it as unsigned. Now ID_AA64DFR0_EL1_PMUVer_IMP_DEF
needs to be special cased, so use pmuv3_implemented() which already does
it.
Fixes: 2417218f2f23 ("KVM: arm64: Get rid of __kvm_get_mdcr_el2() and related warts")
Signed-off-by: James Clark <james.clark@linaro.org>
Reviewed-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Colton Lewis <coltonlewis@google.com>
Signed-off-by: Will Deacon <will@kernel.org>
Pull EFI fix from Ard Biesheuvel:
"Fix for the x86 EFI workaround keeping boot services code and data
regions reserved until after SetVirtualAddressMap() completes:
deferred struct page initialization may result in some of this memory
being lost permanently"
* tag 'efi-fixes-for-v7.0-2' of git://git.kernel.org/pub/scm/linux/kernel/git/efi/efi:
x86/efi: defer freeing of boot services memory
Pull i2c fix from Wolfram Sang:
"A revert for the i801 driver restoring old locking behaviour"
* tag 'i2c-for-7.0-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux:
i2c: i801: Revert "i2c: i801: replace acpi_lock with I2C bus lock"
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