kernel/linux.git/Documentation/trace/index.rst, branch linux-7.1.y

Merge tag 'trace-ringbuffer-v7.1' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

2026-04-15T22:59:46+00:00

Pull ring-buffer updates from Steven Rostedt: - Add remote buffers for pKVM pKVM has a hypervisor component that is used to protect the guest from the host kernel. This hypervisor is a black box to the kernel as the kernel is to user space. The remote buffers are used to have a memory mapping between the hypervisor and the kernel where kernel may send commands to enable tracing within the hypervisor. Then the kernel will read this memory mapping just like user space can read the memory mapped ring buffer of the kernel tracing system. Since the hypervisor only has a single context, it doesn't need to worry about races between normal context, interrupt context and NMIs like the kernel does. The ring buffer it uses doesn't need to be as complex. The remote buffers are a simple version of the ring buffer that works in a single context. They are still per-CPU and use sub buffers. The data layout is the same as the kernel's ring buffer to share the same parsing. Currently, only ARM64 implements pKVM, but there's work to implement it also in x86. The remote buffer code is separated out from the ARM implementation so that it can be used in the future by x86. The ARM64 updates for pKVM is in the ARM/KVM tree and it merged in the remote buffers of this tree. - Make the backup instance non reusable The backup instance is a copy of the persistent ring buffer so that the persistent ring buffer could start recording again without using the data from the previous boot. The backup isn't for normal tracing. It is made read-only, and after it is consumed, it is automatically removed. - Have backup copy persistent instance before it starts recording To allow the persistent ring buffer to start recording from the kernel command line commands, move the copy of the backup instance to before the the command line options start recording. - Report header_page overwrite field as "char" and not "int' The rust parser of the header_page file was triggering a warning when it defined the overwrite variable as "int" but it was only a single byte in size. - Fix memory barriers for the trace_buffer CPU mask When a CPU comes online, the bit is set to allow readers to know that the CPU buffer is allocated. The bit is set after the allocation is done, and a smp_wmb() is performed after the allocation and before the setting of the bit. But instead of adding a smp_rmb() to all readers, since once a buffer is created for a CPU it is not deleted if that CPU goes offline, so this allocation is almost always done at boot up before any readers exist. If for the unlikely case where a CPU comes online for the first time after the system boot has finished, send an IPI to all CPUs to force the smp_rmb() for each CPU. - Show clock function being used in debugging ring buffer data When the ring buffer checks are enabled and the ring buffer detects an inconsistency in the times of the invents, print out the clock being used when the error occurred. There was a very hard to hit bug that would happen every so often and it ended up being only triggered when the jiffies clock was being used. If the bug showed the clock being used, it would have been much easier to find the problem (which was an internal function was being traced which caused the clock accounting to go off). * tag 'trace-ringbuffer-v7.1' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (26 commits) ring-buffer: Prevent off-by-one array access in ring_buffer_desc_page() ring-buffer: Report header_page overwrite as char tracing: Allow backup to save persistent ring buffer before it starts tracing/Documentation: Add a section about backup instance tracing: Remove the backup instance automatically after read tracing: Make the backup instance non-reusable ring-buffer: Enforce read ordering of trace_buffer cpumask and buffers ring-buffer: Show what clock function is used on timestamp errors tracing: Check for undefined symbols in simple_ring_buffer tracing: load/unload page callbacks for simple_ring_buffer Documentation: tracing: Add tracing remotes tracing: selftests: Add trace remote tests tracing: Add a trace remote module for testing tracing: Introduce simple_ring_buffer ring-buffer: Export buffer_data_page and macros tracing: Add helpers to create trace remote events tracing: Add events/ root files to trace remotes tracing: Add events to trace remotes tracing: Add init callback to trace remotes tracing: Add non-consuming read to trace remotes ...

Documentation: tracing: Add PCI controller event documentation

2026-04-07T14:43:12+00:00

The PCI controller tracepoint, pcie_ltssm_state_transition, monitors the LTSSM state transition and data rate changes for debugging purposes. Add documentation for it. Signed-off-by: Shawn Lin [mani: added MAINTAINERS entry] Signed-off-by: Manivannan Sadhasivam Reviewed-by: Steven Rostedt (Google) Link: https://patch.msgid.link/1774403912-210670-3-git-send-email-shawn.lin@rock-chips.com

Documentation: tracing: Add tracing remotes

2026-03-09T16:33:55+00:00

Add documentation about the newly introduced tracing remotes framework. Link: https://patch.msgid.link/20260309162516.2623589-17-vdonnefort@google.com Reviewed-by: Steven Rostedt (Google) Signed-off-by: Vincent Donnefort Signed-off-by: Steven Rostedt (Google)

Merge tag 'pci-v7.0-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/pci/pci

2026-02-12T01:20:38+00:00

Pull PCI updates from Bjorn Helgaas: "Enumeration: - Don't try to enable Extended Tags on VFs since that bit is Reserved and causes misleading log messages (Håkon Bugge) - Initialize Endpoint Read Completion Boundary to match Root Port, regardless of ACPI _HPX (Håkon Bugge) - Apply _HPX PCIe Setting Record only to AER configuration, and only when OS owns PCIe hotplug but not AER, to avoid clobbering Extended Tag and Relaxed Ordering settings (Håkon Bugge) Resource management: - Move CardBus code to setup-cardbus.c and only build it when CONFIG_CARDBUS is set (Ilpo Järvinen) - Fix bridge window alignment with optional resources, where additional alignment requirement was previously lost (Ilpo Järvinen) - Stop over-estimating bridge window size since they are now assigned without any gaps between them (Ilpo Järvinen) - Increase resource MAX_IORES_LEVEL to avoid /proc/iomem flattening for nested bridges and endpoints (Ilpo Järvinen) - Add pbus_mem_size_optional() to handle sizes of optional resources (SR-IOV VF BARs, expansion ROMs, bridge windows) (Ilpo Järvinen) - Don't claim disabled bridge windows to avoid spurious claim failures (Ilpo Järvinen) Driver binding: - Fix device reference leak in pcie_port_remove_service() (Uwe Kleine-König) - Move pcie_port_bus_match() and pcie_port_bus_type to PCIe-specific portdrv.c (Uwe Kleine-König) - Convert portdrv to use pcie_port_bus_type.probe() and .remove() callbacks so .probe() and .remove() can eventually be removed from struct device_driver (Uwe Kleine-König) Error handling: - Clear stale errors on reporting agents upon probe so they don't look like recent errors (Lukas Wunner) - Add generic RAS tracepoint for hotplug events (Shuai Xue) - Add RAS tracepoint for link speed changes (Shuai Xue) Power management: - Avoid redundant delay on transition from D3hot to D3cold if the device was already in D3hot (Brian Norris) - Prevent runtime suspend until devices are fully initialized to avoid saving incompletely configured device state (Brian Norris) Power control: - Add power_on/off callbacks with generic signature to pwrseq, tc9563, and slot drivers so they can be used by pwrctrl core (Manivannan Sadhasivam) - Add PCIe M.2 connector support to the slot pwrctrl driver (Manivannan Sadhasivam) - Switch to pwrctrl interfaces to create, destroy, and power on/off devices, calling them from host controller drivers instead of the PCI core (Manivannan Sadhasivam) - Drop qcom .assert_perst() callbacks since this is now done by the controller driver instead of the pwrctrl driver (Manivannan Sadhasivam) Virtualization: - Remove an incorrect unlock in pci_slot_trylock() error handling (Jinhui Guo) - Lock the bridge device for slot reset (Keith Busch) - Enable ACS after IOMMU configuration on OF platforms so ACS is enabled an all devices; previously the first device enumerated (typically a Root Port) didn't have ACS enabled (Manivannan Sadhasivam) - Disable ACS Source Validation for IDT 0x80b5 and 0x8090 switches to work around hardware erratum; previously ACS SV was only temporarily disabled, which worked for enumeration but not after reset (Manivannan Sadhasivam) Peer-to-peer DMA: - Release per-CPU pgmap ref when vm_insert_page() fails to avoid hang when removing the PCI device (Hou Tao) - Remove incorrect p2pmem_alloc_mmap() warning about page refcount (Hou Tao) Endpoint framework: - Add configfs sub-groups synchronously to avoid NULL pointer dereference when racing with removal (Liu Song) - Fix swapped parameters in pci_{primary/secondary}_epc_epf_unlink() functions (Manikanta Maddireddy) ASPEED PCIe controller driver: - Add ASPEED Root Complex DT binding and driver (Jacky Chou) Freescale i.MX6 PCIe controller driver: - Add DT binding and driver support for an optional external refclock in addition to the refclock from the internal PLL (Richard Zhu) - Fix CLKREQ# control so host asserts it during enumeration and Endpoints can use it afterwards to exit the L1.2 link state (Richard Zhu) NVIDIA Tegra PCIe controller driver: - Export irq_domain_free_irqs() to allow PCI/MSI drivers that tear down MSI domains to be built as modules (Aaron Kling) - Allow pci-tegra to be built as a module (Aaron Kling) NVIDIA Tegra194 PCIe controller driver: - Relax Kconfig so tegra194 can be built for platforms beyond Tegra194 (Vidya Sagar) Qualcomm PCIe controller driver: - Merge SC8180x DT binding into SM8150 (Krzysztof Kozlowski) - Move SDX55, SDM845, QCS404, IPQ5018, IPQ6018, IPQ8074 Gen3, IPQ8074, IPQ4019, IPQ9574, APQ8064, MSM8996, APQ8084 to dedicated schema (Krzysztof Kozlowski) - Add DT binding and driver support for SA8255p Endpoint being configured by firmware (Mrinmay Sarkar) - Parse PERST# from all PCIe bridge nodes for future platforms that will have PERST# in Switch Downstream Ports as well as in Root Ports (Manivannan Sadhasivam) Renesas RZ/G3S PCIe controller driver: - Use pci_generic_config_write() since the writability provided by the custom wrapper is unnecessary (Claudiu Beznea) SOPHGO PCIe controller driver: - Disable ASPM L0s and L1 on Sophgo 2044 PCIe Root Ports (Inochi Amaoto) Synopsys DesignWare PCIe controller driver: - Extend PCI_FIND_NEXT_CAP() and PCI_FIND_NEXT_EXT_CAP() to return a pointer to the preceding Capability, to allow removal of Capabilities that are advertised but not fully implemented (Qiang Yu) - Remove MSI and MSI-X Capabilities in platforms that can't support them, so the PCI core automatically falls back to INTx (Qiang Yu) - Add ASPM L1.1 and L1.2 Substates context to debugfs ltssm_status for drivers that support this (Shawn Lin) - Skip PME_Turn_Off broadcast and L2/L3 transition during suspend if link is not up to avoid an unnecessary timeout (Manivannan Sadhasivam) - Revert dw-rockchip, qcom, and DWC core changes that used link-up IRQs to trigger enumeration instead of waiting for link to be up because the PCI core doesn't allocate bus number space for hierarchies that might be attached (Niklas Cassel) - Make endpoint iATU entry for MSI permanent instead of programming it dynamically, which is slow and racy with respect to other concurrent traffic, e.g., eDMA (Koichiro Den) - Use iMSI-RX MSI target address when possible to fix endpoints using 32-bit MSI (Shawn Lin) - Allow DWC host controller driver probe to continue if device is not found or found but inactive; only fail when there's an error with the link (Manivannan Sadhasivam) - For controllers like NXP i.MX6QP and i.MX7D, where LTSSM registers are not accessible after PME_Turn_Off, simply wait 10ms instead of polling for L2/L3 Ready (Richard Zhu) - Use multiple iATU entries to map large bridge windows and DMA ranges when necessary instead of failing (Samuel Holland) - Add EPC dynamic_inbound_mapping feature bit for Endpoint Controllers that can update BAR inbound address translation without requiring EPF driver to clear/reset the BAR first, and advertise it for DWC-based Endpoints (Koichiro Den) - Add EPC subrange_mapping feature bit for Endpoint Controllers that can map multiple independent inbound regions in a single BAR, implement subrange mapping, advertise it for DWC-based Endpoints, and add Endpoint selftests for it (Koichiro Den) - Make resizable BARs work for Endpoint multi-PF configurations; previously it only worked for PF 0 (Aksh Garg) - Fix Endpoint non-PF 0 support for BAR configuration, ATU mappings, and Address Match Mode (Aksh Garg) - Set up iATU when ECAM is enabled; previously IO and MEM outbound windows weren't programmed, and ECAM-related iATU entries weren't restored after suspend/resume, so config accesses failed (Krishna Chaitanya Chundru) Miscellaneous: - Use system_percpu_wq and WQ_PERCPU to explicitly request per-CPU work so WQ_UNBOUND can eventually be removed (Marco Crivellari)" * tag 'pci-v7.0-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/pci/pci: (176 commits) PCI/bwctrl: Disable BW controller on Intel P45 using a quirk PCI: Disable ACS SV for IDT 0x8090 switch PCI: Disable ACS SV for IDT 0x80b5 switch PCI: Cache ACS Capabilities register PCI: Enable ACS after configuring IOMMU for OF platforms PCI: Add ACS quirk for Pericom PI7C9X2G404 switches [12d8:b404] PCI: Add ACS quirk for Qualcomm Hamoa & Glymur PCI: Use device_lock_assert() to verify device lock is held PCI: Use lockdep_assert_held(pci_bus_sem) to verify lock is held PCI: Fix pci_slot_lock () device locking PCI: Fix pci_slot_trylock() error handling PCI: Mark Nvidia GB10 to avoid bus reset PCI: Mark ASM1164 SATA controller to avoid bus reset PCI: host-generic: Avoid reporting incorrect 'missing reg property' error PCI/PME: Replace RMW of Root Status register with direct write PCI/AER: Clear stale errors on reporting agents upon probe PCI: Don't claim disabled bridge windows PCI: rzg3s-host: Fix device node reference leak in rzg3s_pcie_host_parse_port() PCI: dwc: Fix missing iATU setup when ECAM is enabled PCI: dwc: Clean up iATU index usage in dw_pcie_iatu_setup() ...

Documentation: use a source-read extension for the index link boilerplate

2026-01-23T18:59:34+00:00

The root document usually has a special :ref:`genindex` link to the generated index. This is also the case for Documentation/index.rst. The other index.rst files deeper in the directory hierarchy usually don't. For SPHINXDIRS builds, the root document isn't Documentation/index.rst, but some other index.rst in the hierarchy. Currently they have a ".. only::" block to add the index link when doing SPHINXDIRS html builds. This is obviously very tedious and repetitive. The link is also added to all index.rst files in the hierarchy for SPHINXDIRS builds, not just the root document. Put the boilerplate in a sphinx-includes/subproject-index.rst file, and include it at the end of the root document for subproject builds in an ad-hoc source-read extension defined in conf.py. For now, keep having the boilerplate in translations, because this approach currently doesn't cover translated index link headers. Cc: Jonathan Corbet Cc: Mauro Carvalho Chehab Cc: Randy Dunlap Signed-off-by: Jani Nikula Tested-by: Mauro Carvalho Chehab Reviewed-by: Mauro Carvalho Chehab [jc: did s/doctree/kern_doc_dir/ ] Signed-off-by: Jonathan Corbet Message-ID: <20260123143149.2024303-1-jani.nikula@intel.com>

Documentation: tracing: Add PCI tracepoint documentation

2026-01-08T16:06:19+00:00

The PCI tracing system provides tracepoints to monitor critical hardware events that can impact system performance and reliability. Add documentation about it. Signed-off-by: Shuai Xue [bhelgaas: squash fixes: https://lore.kernel.org/r/20260108013956.14351-2-bagasdotme@gmail.com https://lore.kernel.org/r/20260108013956.14351-3-bagasdotme@gmail.com] Signed-off-by: Bjorn Helgaas Reviewed-by: Ilpo Järvinen Link: https://patch.msgid.link/20251210132907.58799-4-xueshuai@linux.alibaba.com

Documentation: tracing: Add documentation about eprobes

2025-07-30T14:38:43+00:00

Eprobes was added back in 5.15, but was never documented. It became a "secret" interface even though it has been a topic of several presentations. For some reason, when eprobes was added, documenting it never became a priority, until now. Cc: Mark Rutland Cc: Mathieu Desnoyers Cc: Andrew Morton Cc: Namhyung Kim Cc: Jonathan Corbet Link: https://lore.kernel.org/20250730140945.528135548@kernel.org Reviewed-by: Randy Dunlap Acked-by: Masami Hiramatsu (Google) Signed-off-by: Steven Rostedt (Google)

Documentation: trace: Refactor toctree

2025-04-21T16:37:13+00:00

Refactor table of contents of kernel tracing subsystem docs to improve clarity, structure, and organization: - Reformat sections and add appropriate headings - Improve section grouping and refine descriptions for each group - Add docs intro paragraph Signed-off-by: Purva Yeshi Link: https://lore.kernel.org/r/20250318113230.24950-2-purvayeshi550@gmail.com [Bagas: massage commit message and address reviews] Co-developed-by: Bagas Sanjaya Signed-off-by: Bagas Sanjaya Acked-by: Steven Rostedt (Google) Signed-off-by: Jonathan Corbet

Documentation: trace: Reduce toctree depth

2025-04-21T16:37:01+00:00

Reduce toctree depth from 2 to 1 so that only docs titles are listed in the toctree. Signed-off-by: Purva Yeshi Link: https://lore.kernel.org/r/20250318113230.24950-1-purvayeshi550@gmail.com [Bagas: massage commit message] Signed-off-by: Bagas Sanjaya Acked-by: Steven Rostedt (Google) Signed-off-by: Jonathan Corbet

docs: fix WARNING document not included in any toctree

2024-10-07T17:50:54+00:00

Add debugging.rst to the relevant toctree to fix warning about missing documentation inclusion in toctree. Signed-off-by: SurajSonawane2415 Signed-off-by: Jonathan Corbet Link: https://lore.kernel.org/r/20241002195817.22972-1-surajsonawane0215@gmail.com