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source | linux | .. SPDX-License-Identifier: GPL-2.0
:Author: Deepak Gupta <debug@rivosinc.com>
:Date: 12 January 2024
====================================================
Tracking indirect control transfers on RISC-V Linux
====================================================
This document briefly describes the interface provided ... | Documentation/arch/riscv/zicfilp.rst | null | null | null | null | null |
source | linux | .. SPDX-License-Identifier: GPL-2.0
:Author: Deepak Gupta <debug@rivosinc.com>
:Date: 12 January 2024
=========================================================
Shadow stack to protect function returns on RISC-V Linux
=========================================================
This document briefly describes the inte... | Documentation/arch/riscv/zicfiss.rst | null | null | null | null | null |
source | linux | ===============================
IBM 3270 Display System support
===============================
This file describes the driver that supports local channel attachment
of IBM 3270 devices. It consists of three sections:
* Introduction
* Installation
* Operation
Introduction
============
This paper describes inst... | Documentation/arch/s390/3270.rst | null | null | null | null | null |
source | linux | ===========================
Linux for S/390 and zSeries
===========================
Common Device Support (CDS)
Device Driver I/O Support Routines
Authors:
- Ingo Adlung
- Cornelia Huck
Copyright, IBM Corp. 1999-2002
Introduction
============
This document describes the common device support routines for Linux/3... | Documentation/arch/s390/cds.rst | null | null | null | null | null |
source | linux | ======================
S/390 common I/O-Layer
======================
command line parameters, procfs and debugfs entries
===================================================
Command line parameters
-----------------------
* ccw_timeout_log
Enable logging of debug information in case of ccw device timeouts.
* cio_... | Documentation/arch/s390/common_io.rst | null | null | null | null | null |
source | linux | =============================
S/390 driver model interfaces
=============================
1. CCW devices
--------------
All devices which can be addressed by means of ccws are called 'CCW devices' -
even if they aren't actually driven by ccws.
All ccw devices are accessed via a subchannel, this is reflected in the
s... | Documentation/arch/s390/driver-model.rst | null | null | null | null | null |
source | linux | =================
s390 Architecture
=================
.. toctree::
:maxdepth: 1
cds
3270
driver-model
mm
monreader
qeth
s390dbf
vfio-ap
vfio-ap-locking
vfio-ccw
zfcpdump
common_io
pci
text_files
features | Documentation/arch/s390/index.rst | null | null | null | null | null |
source | linux | .. SPDX-License-Identifier: GPL-2.0
=================
Memory Management
=================
Virtual memory layout
=====================
.. note::
- Some aspects of the virtual memory layout setup are not
clarified (number of page levels, alignment, DMA memory).
- Unused gaps in the virtual memory layout could b... | Documentation/arch/s390/mm.rst | null | null | null | null | null |
source | linux | =================================================
Linux API for read access to z/VM Monitor Records
=================================================
Date : 2004-Nov-26
Author: Gerald Schaefer (geraldsc@de.ibm.com)
Description
===========
This item delivers a new Linux API in the form of a misc char device that ... | Documentation/arch/s390/monreader.rst | null | null | null | null | null |
source | linux | .. SPDX-License-Identifier: GPL-2.0
=========
S/390 PCI
=========
Authors:
- Pierre Morel
Copyright, IBM Corp. 2020
Command line parameters and debugfs entries
===========================================
Command line parameters
-----------------------
* nomio
Do not use PCI Mapped I/O (MIO) instructio... | Documentation/arch/s390/pci.rst | null | null | null | null | null |
source | linux | =============================
IBM s390 QDIO Ethernet Driver
=============================
OSA and HiperSockets Bridge Port Support
========================================
Uevents
-------
To generate the events the device must be assigned a role of either
a primary or a secondary Bridge Port. For more information, s... | Documentation/arch/s390/qeth.rst | null | null | null | null | null |
source | linux | ==================
S390 Debug Feature
==================
files:
- arch/s390/kernel/debug.c
- arch/s390/include/asm/debug.h
Description:
------------
The goal of this feature is to provide a kernel debug logging API
where log records can be stored efficiently in memory, where each component
(e.g. device dr... | Documentation/arch/s390/s390dbf.rst | null | null | null | null | null |
source | linux | ibm 3270 changelog
------------------
.. include:: 3270.ChangeLog
:literal:
ibm 3270 config3270.sh
----------------------
.. literalinclude:: config3270.sh
:language: shell | Documentation/arch/s390/text_files.rst | null | null | null | null | null |
source | linux | .. SPDX-License-Identifier: GPL-2.0
======================
VFIO AP Locks Overview
======================
This document describes the locks that are pertinent to the secure operation
of the vfio_ap device driver. Throughout this document, the following variables
will be used to denote instances of the structures herein... | Documentation/arch/s390/vfio-ap-locking.rst | null | null | null | null | null |
source | linux | ===============================
Adjunct Processor (AP) facility
===============================
Introduction
============
The Adjunct Processor (AP) facility is an IBM Z cryptographic facility comprised
of three AP instructions and from 1 up to 256 PCIe cryptographic adapter cards.
The AP devices provide cryptographi... | Documentation/arch/s390/vfio-ap.rst | null | null | null | null | null |
source | linux | ==================================
vfio-ccw: the basic infrastructure
==================================
Introduction
------------
Here we describe the vfio support for I/O subchannel devices for
Linux/s390. Motivation for vfio-ccw is to passthrough subchannels to a
virtual machine, while vfio is the means.
Differen... | Documentation/arch/s390/vfio-ccw.rst | null | null | null | null | null |
source | linux | ==================================
The s390 SCSI dump tool (zfcpdump)
==================================
System z machines (z900 or higher) provide hardware support for creating system
dumps on SCSI disks. The dump process is initiated by booting a dump tool, which
has to create a dump of the current (probably crashed... | Documentation/arch/s390/zfcpdump.rst | null | null | null | null | null |
source | linux | .. SPDX-License-Identifier: GPL-2.0
DeviceTree Booting
------------------
Device-tree compatible SH bootloaders are expected to provide the physical
address of the device tree blob in r4. Since legacy bootloaders did not
guarantee any particular initial register state, kernels built to
inter-operate with old ... | Documentation/arch/sh/booting.rst | null | null | null | null | null |
source | linux | =======================
SuperH Interfaces Guide
=======================
:Author: Paul Mundt
.. toctree::
:maxdepth: 1
booting
new-machine
register-banks
features
Memory Management
=================
SH-4
----
Store Queue API
~~~~~~~~~~~~~~~
.. kernel-doc:: arch/sh/kernel/cpu/sh4/sq.c
:expo... | Documentation/arch/sh/index.rst | null | null | null | null | null |
source | linux | .. SPDX-License-Identifier: GPL-2.0
=============================
Adding a new board to LinuxSH
=============================
Paul Mundt <lethal@linux-sh.org>
This document attempts to outline what steps are necessary to add support
for new boards to the LinuxSH port under the new 2.5 and 2.6 kernels.... | Documentation/arch/sh/new-machine.rst | null | null | null | null | null |
source | linux | .. SPDX-License-Identifier: GPL-2.0
==========================================
Notes on register bank usage in the kernel
==========================================
Introduction
------------
The SH-3 and SH-4 CPU families traditionally include a single partial register
bank (selected by SR.RB, only r0 ... r7 are ban... | Documentation/arch/sh/register-banks.rst | null | null | null | null | null |
source | linux | ================================
Application Data Integrity (ADI)
================================
SPARC M7 processor adds the Application Data Integrity (ADI) feature.
ADI allows a task to set version tags on any subset of its address
space. Once ADI is enabled and version tags are set for ranges of
address space of ... | Documentation/arch/sparc/adi.rst | null | null | null | null | null |
source | linux | Steps for sending 'break' on sunhv console
==========================================
On Baremetal:
1. press Esc + 'B'
On LDOM:
1. press Ctrl + ']'
2. telnet> send break | Documentation/arch/sparc/console.rst | null | null | null | null | null |
source | linux | ==================
Sparc Architecture
==================
.. toctree::
:maxdepth: 1
console
adi
oradax/oracle-dax
features | Documentation/arch/sparc/index.rst | null | null | null | null | null |
source | linux | Excerpt from UltraSPARC Virtual Machine Specification
Compiled from version 3.0.20+15
Publication date 2017-09-25 08:21
Copyright © 2008, 2015 Oracle and/or its affiliates. All rights reserved.
Extracted via "pdftotext -f 547 -l 572 -layout sun4v_20170925.pdf"
Authors:
Charles Kunzman
Sam Glidden
Mark Cianchetti
... | Documentation/arch/sparc/oradax/dax-hv-api.txt | null | null | null | null | null |
source | linux | =======================================
Oracle Data Analytics Accelerator (DAX)
=======================================
DAX is a coprocessor which resides on the SPARC M7 (DAX1) and M8
(DAX2) processor chips, and has direct access to the CPU's L3 caches
as well as physical memory. It can perform several operations on ... | Documentation/arch/sparc/oradax/oracle-dax.rst | null | null | null | null | null |
source | linux | .. SPDX-License-Identifier: GPL-2.0
Debugging AMD Zen systems
+++++++++++++++++++++++++
Introduction
============
This document describes techniques that are useful for debugging issues with
AMD Zen systems. It is intended for use by developers and technical users
to help identify and resolve issues.
S3 vs s2idle
... | Documentation/arch/x86/amd-debugging.rst | null | null | null | null | null |
source | linux | .. SPDX-License-Identifier: GPL-2.0
======================================================================
Hardware Feedback Interface For Hetero Core Scheduling On AMD Platform
======================================================================
:Copyright: 2025 Advanced Micro Devices, Inc. All Rights Reserved.
:... | Documentation/arch/x86/amd-hfi.rst | null | null | null | null | null |
source | linux | .. SPDX-License-Identifier: GPL-2.0
=====================
AMD Memory Encryption
=====================
Secure Memory Encryption (SME) and Secure Encrypted Virtualization (SEV) are
features found on AMD processors.
SME provides the ability to mark individual pages of memory as encrypted using
the standard x86 page tab... | Documentation/arch/x86/amd-memory-encryption.rst | null | null | null | null | null |
source | linux | .. SPDX-License-Identifier: GPL-2.0
============================================
AMD HSMP interface
============================================
Newer Fam19h(model 0x00-0x1f, 0x30-0x3f, 0x90-0x9f, 0xa0-0xaf),
Fam1Ah(model 0x00-0x1f) EPYC server line of processors from AMD support
system management functionality via H... | Documentation/arch/x86/amd_hsmp.rst | null | null | null | null | null |
source | linux | .. SPDX-License-Identifier: GPL-2.0
===========================
The Linux/x86 Boot Protocol
===========================
On the x86 platform, the Linux kernel uses a rather complicated boot
convention. This has evolved partially due to historical aspects, as
well as the desire in the early days to have the kernel its... | Documentation/arch/x86/boot.rst | null | null | null | null | null |
source | linux | .. SPDX-License-Identifier: GPL-2.0
DeviceTree Booting
------------------
There is one single 32bit entry point to the kernel at code32_start,
the decompressor (the real mode entry point goes to the same 32bit
entry point once it switched into protected mode). That entry point
supports one calling convention... | Documentation/arch/x86/booting-dt.rst | null | null | null | null | null |
source | linux | .. SPDX-License-Identifier: GPL-2.0
.. include:: <isonum.txt>
===============================
Bus lock detection and handling
===============================
:Copyright: |copy| 2021 Intel Corporation
:Authors: - Fenghua Yu <fenghua.yu@intel.com>
- Tony Luck <tony.luck@intel.com>
Problem
=======
A split l... | Documentation/arch/x86/buslock.rst | null | null | null | null | null |
source | linux | .. SPDX-License-Identifier: GPL-2.0
=================
x86 Feature Flags
=================
Introduction
============
The list of feature flags in /proc/cpuinfo is not complete and
represents an ill-fated attempt from long time ago to put feature flags
in an easy to find place for userspace.
However, the number of fe... | Documentation/arch/x86/cpuinfo.rst | null | null | null | null | null |
source | linux | .. SPDX-License-Identifier: GPL-2.0
============
Early Printk
============
Mini-HOWTO for using the earlyprintk=dbgp boot option with a
USB2 Debug port key and a debug cable, on x86 systems.
You need two computers, the 'USB debug key' special gadget and
two USB cables, connected like this::
[host/target] <-------... | Documentation/arch/x86/earlyprintk.rst | null | null | null | null | null |
source | linux | .. SPDX-License-Identifier: GPL-2.0
==================================
x86-specific ELF Auxiliary Vectors
==================================
This document describes the semantics of the x86 auxiliary vectors.
Introduction
============
ELF Auxiliary vectors enable the kernel to efficiently provide
configuration-spec... | Documentation/arch/x86/elf_auxvec.rst | null | null | null | null | null |
source | linux | .. SPDX-License-Identifier: GPL-2.0
==============
Kernel Entries
==============
This file documents some of the kernel entries in
arch/x86/entry/entry_64.S. A lot of this explanation is adapted from
an email from Ingo Molnar:
https://lore.kernel.org/r/20110529191055.GC9835%40elte.hu
The x86 architecture has quite... | Documentation/arch/x86/entry_64.rst | null | null | null | null | null |
source | linux | .. SPDX-License-Identifier: GPL-2.0
===============================
Kernel level exception handling
===============================
Commentary by Joerg Pommnitz <joerg@raleigh.ibm.com>
When a process runs in kernel mode, it often has to access user
mode memory whose address has been passed by an untrusted program.
T... | Documentation/arch/x86/exception-tables.rst | null | null | null | null | null |
source | linux | .. SPDX-License-Identifier: GPL-2.0
==========================
x86-specific Documentation
==========================
.. toctree::
:maxdepth: 2
:numbered:
boot
booting-dt
cpuinfo
topology
exception-tables
kernel-stacks
entry_64
earlyprintk
orc-unwinder
zero-page
tlb
mtrr
p... | Documentation/arch/x86/index.rst | null | null | null | null | null |
source | linux | .. SPDX-License-Identifier: GPL-2.0
============================================================
Hardware-Feedback Interface for scheduling on Intel Hardware
============================================================
Overview
--------
Intel has described the Hardware Feedback Interface (HFI) in the Intel 64 and
IA... | Documentation/arch/x86/intel-hfi.rst | null | null | null | null | null |
source | linux | =====================
Intel(R) TXT Overview
=====================
Intel's technology for safer computing, Intel(R) Trusted Execution
Technology (Intel(R) TXT), defines platform-level enhancements that
provide the building blocks for creating trusted platforms.
Intel TXT was formerly known by the code name LaGrande Te... | Documentation/arch/x86/intel_txt.rst | null | null | null | null | null |
source | linux | =================
x86 IOMMU Support
=================
The architecture specs can be obtained from the vendor websites.
Search for the following documents to obtain the latest versions:
- Intel: Intel Virtualization Technology for Directed I/O Architecture Specification (ID: D51397)
- AMD: AMD I/O Virtualization Techn... | Documentation/arch/x86/iommu.rst | null | null | null | null | null |
source | linux | .. SPDX-License-Identifier: GPL-2.0
=============
Kernel Stacks
=============
Kernel stacks on x86-64 bit
===========================
Most of the text from Keith Owens, hacked by AK
x86_64 page size (PAGE_SIZE) is 4K.
Like all other architectures, x86_64 has a kernel stack for every
active thread. These thread st... | Documentation/arch/x86/kernel-stacks.rst | null | null | null | null | null |
source | linux | Microarchitectural Data Sampling (MDS) mitigation
=================================================
.. _mds:
Overview
--------
Microarchitectural Data Sampling (MDS) is a family of side channel attacks
on internal buffers in Intel CPUs. The variants are:
- Microarchitectural Store Buffer Data Sampling (MSBDS) (CVE... | Documentation/arch/x86/mds.rst | null | null | null | null | null |
source | linux | .. SPDX-License-Identifier: GPL-2.0
==========================
The Linux Microcode Loader
==========================
:Authors: - Fenghua Yu <fenghua.yu@intel.com>
- Borislav Petkov <bp@suse.de>
- Ashok Raj <ashok.raj@intel.com>
The kernel has a x86 microcode loading facility which is supposed to
provide... | Documentation/arch/x86/microcode.rst | null | null | null | null | null |
source | linux | .. SPDX-License-Identifier: GPL-2.0
=========================================
MTRR (Memory Type Range Register) control
=========================================
:Authors: - Richard Gooch <rgooch@atnf.csiro.au> - 3 Jun 1999
- Luis R. Rodriguez <mcgrof@do-not-panic.com> - April 9, 2015
Phasing out MTRR use... | Documentation/arch/x86/mtrr.rst | null | null | null | null | null |
source | linux | .. SPDX-License-Identifier: GPL-2.0
============
ORC unwinder
============
Overview
========
The kernel CONFIG_UNWINDER_ORC option enables the ORC unwinder, which is
similar in concept to a DWARF unwinder. The difference is that the
format of the ORC data is much simpler than DWARF, which in turn allows
the ORC unw... | Documentation/arch/x86/orc-unwinder.rst | null | null | null | null | null |
source | linux | .. SPDX-License-Identifier: GPL-2.0
==========================
PAT (Page Attribute Table)
==========================
x86 Page Attribute Table (PAT) allows for setting the memory attribute at the
page level granularity. PAT is complementary to the MTRR settings which allows
for setting of memory types over physical ad... | Documentation/arch/x86/pat.rst | null | null | null | null | null |
source | linux | .. SPDX-License-Identifier: GPL-2.0
==========================
Page Table Isolation (PTI)
==========================
Overview
========
Page Table Isolation (pti, previously known as KAISER [1]_) is a
countermeasure against attacks on the shared user/kernel address
space such as the "Meltdown" approach [2]_.
To miti... | Documentation/arch/x86/pti.rst | null | null | null | null | null |
source | linux | .. SPDX-License-Identifier: GPL-2.0
===============================
Software Guard eXtensions (SGX)
===============================
Overview
========
Software Guard eXtensions (SGX) hardware enables for user space applications
to set aside private memory regions of code and data:
* Privileged (ring-0) ENCLS functio... | Documentation/arch/x86/sgx.rst | null | null | null | null | null |
source | linux | .. SPDX-License-Identifier: GPL-2.0
======================================================
Control-flow Enforcement Technology (CET) Shadow Stack
======================================================
CET Background
==============
Control-flow Enforcement Technology (CET) covers several related x86 processor
feature... | Documentation/arch/x86/shstk.rst | null | null | null | null | null |
source | linux | .. SPDX-License-Identifier: GPL-2.0
===========================================
Shared Virtual Addressing (SVA) with ENQCMD
===========================================
Background
==========
Shared Virtual Addressing (SVA) allows the processor and device to use the
same virtual addresses avoiding the need for softwar... | Documentation/arch/x86/sva.rst | null | null | null | null | null |
source | linux | .. SPDX-License-Identifier: GPL-2.0
=====================================
Intel Trust Domain Extensions (TDX)
=====================================
Intel's Trust Domain Extensions (TDX) protect confidential guest VMs from
the host and physical attacks by isolating the guest register state and by
encrypting the guest ... | Documentation/arch/x86/tdx.rst | null | null | null | null | null |
source | linux | .. SPDX-License-Identifier: GPL-2.0
=======
The TLB
=======
When the kernel unmaps or modified the attributes of a range of
memory, it has two choices:
1. Flush the entire TLB with a two-instruction sequence. This is
a quick operation, but it causes collateral damage: TLB entries
from areas other than the ... | Documentation/arch/x86/tlb.rst | null | null | null | null | null |
source | linux | .. SPDX-License-Identifier: GPL-2.0
============
x86 Topology
============
This documents and clarifies the main aspects of x86 topology modelling and
representation in the kernel. Update/change when doing changes to the
respective code.
The architecture-agnostic topology definitions are in
Documentation/admin-guide... | Documentation/arch/x86/topology.rst | null | null | null | null | null |
source | linux | .. SPDX-License-Identifier: GPL-2.0
TSX Async Abort (TAA) mitigation
================================
.. _tsx_async_abort:
Overview
--------
TSX Async Abort (TAA) is a side channel attack on internal buffers in some
Intel processors similar to Microachitectural Data Sampling (MDS). In this
case certain loads may s... | Documentation/arch/x86/tsx_async_abort.rst | null | null | null | null | null |
source | linux | .. SPDX-License-Identifier: GPL-2.0
==================
USB Legacy support
==================
:Author: Vojtech Pavlik <vojtech@suse.cz>, January 2004
Also known as "USB Keyboard" or "USB Mouse support" in the BIOS Setup is a
feature that allows one to use the USB mouse and keyboard as if they were
their classic PS/2... | Documentation/arch/x86/usb-legacy-support.rst | null | null | null | null | null |
source | linux | Using XSTATE features in user space applications
================================================
The x86 architecture supports floating-point extensions which are
enumerated via CPUID. Applications consult CPUID and use XGETBV to
evaluate which features have been enabled by the kernel XCR0.
Up to AVX-512 and PKRU st... | Documentation/arch/x86/xstate.rst | null | null | null | null | null |
source | linux | .. SPDX-License-Identifier: GPL-2.0
=========
Zero Page
=========
The additional fields in struct boot_params as a part of 32-bit boot
protocol of kernel. These should be filled by bootloader or 16-bit
real-mode setup code of the kernel. References/settings to it mainly
are in::
arch/x86/include/uapi/asm/bootparam.... | Documentation/arch/x86/zero-page.rst | null | null | null | null | null |
source | linux | .. SPDX-License-Identifier: GPL-2.0
=======
IO-APIC
=======
:Author: Ingo Molnar <mingo@kernel.org>
Most (all) Intel-MP compliant SMP boards have the so-called 'IO-APIC',
which is an enhanced interrupt controller. It enables us to route
hardware interrupts to multiple CPUs, or to CPU groups. Without an
IO-APIC, inte... | Documentation/arch/x86/i386/IO-APIC.rst | null | null | null | null | null |
source | linux | .. SPDX-License-Identifier: GPL-2.0
============
i386 Support
============
.. toctree::
:maxdepth: 2
IO-APIC | Documentation/arch/x86/i386/index.rst | null | null | null | null | null |
source | linux | .. SPDX-License-Identifier: GPL-2.0
==============
5-level paging
==============
Overview
========
Original x86-64 was limited by 4-level paging to 256 TiB of virtual address
space and 64 TiB of physical address space. We are already bumping into
this limit: some vendors offer servers with 64 TiB of memory today.
To... | Documentation/arch/x86/x86_64/5level-paging.rst | null | null | null | null | null |
source | linux | .. SPDX-License-Identifier: GPL-2.0
===================================================
Firmware support for CPU hotplug under Linux/x86-64
===================================================
Linux/x86-64 supports CPU hotplug now. For various reasons Linux wants to
know in advance of boot time the maximum number of C... | Documentation/arch/x86/x86_64/cpu-hotplug-spec.rst | null | null | null | null | null |
source | linux | .. SPDX-License-Identifier: GPL-2.0
=====================
Fake NUMA For CPUSets
=====================
:Author: David Rientjes <rientjes@cs.washington.edu>
Using numa=fake and CPUSets for Resource Management
This document describes how the numa=fake x86_64 command-line option can be used
in conjunction with cpusets ... | Documentation/arch/x86/x86_64/fake-numa-for-cpusets.rst | null | null | null | null | null |
source | linux | .. SPDX-License-Identifier: GPL-2.0
=========================================
Flexible Return and Event Delivery (FRED)
=========================================
Overview
========
The FRED architecture defines simple new transitions that change
privilege level (ring transitions). The FRED architecture was
designed w... | Documentation/arch/x86/x86_64/fred.rst | null | null | null | null | null |
source | linux | .. SPDX-License-Identifier: GPL-2.0
Using FS and GS segments in user space applications
===================================================
The x86 architecture supports segmentation. Instructions which access
memory can use segment register based addressing mode. The following
notation is used to address a byte with... | Documentation/arch/x86/x86_64/fsgs.rst | null | null | null | null | null |
source | linux | .. SPDX-License-Identifier: GPL-2.0
==============
x86_64 Support
==============
.. toctree::
:maxdepth: 2
uefi
mm
5level-paging
fake-numa-for-cpusets
cpu-hotplug-spec
machinecheck
fsgs
fred | Documentation/arch/x86/x86_64/index.rst | null | null | null | null | null |
source | linux | .. SPDX-License-Identifier: GPL-2.0
===============================================================
Configurable sysfs parameters for the x86-64 machine check code
===============================================================
Machine checks report internal hardware error conditions detected
by the CPU. Uncorrected ... | Documentation/arch/x86/x86_64/machinecheck.rst | null | null | null | null | null |
source | linux | .. SPDX-License-Identifier: GPL-2.0
=================
Memory Management
=================
Complete virtual memory map with 4-level page tables
====================================================
.. note::
- Negative addresses such as "-23 TB" are absolute addresses in bytes, counted down
from the top of the 64... | Documentation/arch/x86/x86_64/mm.rst | null | null | null | null | null |
source | linux | .. SPDX-License-Identifier: GPL-2.0
=====================================
General note on [U]EFI x86_64 support
=====================================
The nomenclature EFI and UEFI are used interchangeably in this document.
Although the tools below are _not_ needed for building the kernel,
the needed bootloader suppo... | Documentation/arch/x86/x86_64/uefi.rst | null | null | null | null | null |
source | linux | ===========================================
Atomic Operation Control (ATOMCTL) Register
===========================================
We Have Atomic Operation Control (ATOMCTL) Register.
This register determines the effect of using a S32C1I instruction
with various combinations of:
1. With and without an Coherent ... | Documentation/arch/xtensa/atomctl.rst | null | null | null | null | null |
source | linux | =====================================
Passing boot parameters to the kernel
=====================================
Boot parameters are represented as a TLV list in the memory. Please see
arch/xtensa/include/asm/bootparam.h for definition of the bp_tag structure and
tag value constants. First entry in the list must have... | Documentation/arch/xtensa/booting.rst | null | null | null | null | null |
source | linux | .. SPDX-License-Identifier: GPL-2.0
===================
Xtensa Architecture
===================
.. toctree::
:maxdepth: 1
atomctl
booting
mmu
features | Documentation/arch/xtensa/index.rst | null | null | null | null | null |
source | linux | =============================
MMUv3 initialization sequence
=============================
The code in the initialize_mmu macro sets up MMUv3 memory mapping
identically to MMUv2 fixed memory mapping. Depending on
CONFIG_INITIALIZE_XTENSA_MMU_INSIDE_VMLINUX symbol this code is
located in addresses it was linked for (sym... | Documentation/arch/xtensa/mmu.rst | null | null | null | null | null |
source | linux | ==========================
BFQ (Budget Fair Queueing)
==========================
BFQ is a proportional-share I/O scheduler, with some extra
low-latency capabilities. In addition to cgroups support (blkio or io
controllers), BFQ's main features are:
- BFQ guarantees a high system and application responsiveness, and a
... | Documentation/block/bfq-iosched.rst | null | null | null | null | null |
source | linux | ======================================
Immutable biovecs and biovec iterators
======================================
Kent Overstreet <kmo@daterainc.com>
As of 3.13, biovecs should never be modified after a bio has been submitted.
Instead, we have a new struct bvec_iter which represents a range of a biovec -
the itera... | Documentation/block/biovecs.rst | null | null | null | null | null |
source | linux | .. SPDX-License-Identifier: GPL-2.0
================================================
Multi-Queue Block IO Queueing Mechanism (blk-mq)
================================================
The Multi-Queue Block IO Queueing Mechanism is an API to enable fast storage
devices to achieve a huge number of input/output operation... | Documentation/block/blk-mq.rst | null | null | null | null | null |
source | linux | ==============================================
Embedded device command line partition parsing
==============================================
The "blkdevparts" command line option adds support for reading the
block device partition table from the kernel command line.
It is typically used for fixed block (eMMC) embedde... | Documentation/block/cmdline-partition.rst | null | null | null | null | null |
source | linux | ==============
Data Integrity
==============
1. Introduction
===============
Modern filesystems feature checksumming of data and metadata to
protect against data corruption. However, the detection of the
corruption is done at read time which could potentially be months
after the data was written. At that point the ... | Documentation/block/data-integrity.rst | null | null | null | null | null |
source | linux | ==============================
Deadline IO scheduler tunables
==============================
This little file attempts to document how the deadline io scheduler works.
In particular, it will clarify the meaning of the exposed tunables that may be
of interest to power users.
Selecting IO schedulers
-------------------... | Documentation/block/deadline-iosched.rst | null | null | null | null | null |
source | linux | .. SPDX-License-Identifier: GPL-2.0
=====
Block
=====
.. toctree::
:maxdepth: 1
bfq-iosched
biovecs
blk-mq
cmdline-partition
data-integrity
deadline-iosched
inline-encryption
ioprio
kyber-iosched
null_blk
pr
stat
switching-sched
writeback_cache_control
ublk | Documentation/block/index.rst | null | null | null | null | null |
source | linux | .. SPDX-License-Identifier: GPL-2.0
.. _inline_encryption:
=================
Inline Encryption
=================
Background
==========
Inline encryption hardware sits logically between memory and disk, and can
en/decrypt data as it goes in/out of the disk. For each I/O request, software
can control exactly how the... | Documentation/block/inline-encryption.rst | null | null | null | null | null |
source | linux | ===================
Block io priorities
===================
Intro
-----
The io priority feature enables users to io nice processes or process groups,
similar to what has been possible with cpu scheduling for ages. Support for io
priorities is io scheduler dependent and currently supported by bfq and
mq-deadline.
Sc... | Documentation/block/ioprio.rst | null | null | null | null | null |
source | linux | ============================
Kyber I/O scheduler tunables
============================
The only two tunables for the Kyber scheduler are the target latencies for
reads and synchronous writes. Kyber will throttle requests in order to meet
these target latencies.
read_lat_nsec
-------------
Target latency for reads (in... | Documentation/block/kyber-iosched.rst | null | null | null | null | null |
source | linux | .. SPDX-License-Identifier: GPL-2.0
========================
Null block device driver
========================
Overview
========
The null block device (``/dev/nullb*``) is used for benchmarking the various
block-layer implementations. It emulates a block device of X gigabytes in size.
It does not execute any read/wr... | Documentation/block/null_blk.rst | null | null | null | null | null |
source | linux | ===============================================
Block layer support for Persistent Reservations
===============================================
The Linux kernel supports a user space interface for simplified
Persistent Reservations which map to block devices that support
these (like SCSI). Persistent Reservations allo... | Documentation/block/pr.rst | null | null | null | null | null |
source | linux | ===============================================
Block layer statistics in /sys/block/<dev>/stat
===============================================
This file documents the contents of the /sys/block/<dev>/stat file.
The stat file provides several statistics about the state of block
device <dev>.
Q.
Why are there mult... | Documentation/block/stat.rst | null | null | null | null | null |
source | linux | ===================
Switching Scheduler
===================
Each io queue has a set of io scheduler tunables associated with it. These
tunables control how the io scheduler works. You can find these entries
in::
/sys/block/<device>/queue/iosched
assuming that you have sysfs mounted on /sys. If you don't have sysfs ... | Documentation/block/switching-sched.rst | null | null | null | null | null |
source | linux | .. SPDX-License-Identifier: GPL-2.0
===========================================
Userspace block device driver (ublk driver)
===========================================
Overview
========
ublk is a generic framework for implementing block device logic from userspace.
The motivation behind it is that moving virtual blo... | Documentation/block/ublk.rst | null | null | null | null | null |
source | linux | ==========================================
Explicit volatile write back cache control
==========================================
Introduction
------------
Many storage devices, especially in the consumer market, come with volatile
write back caches. That means the devices signal I/O completion to the
operating syste... | Documentation/block/writeback_cache_control.rst | null | null | null | null | null |
source | linux | ==============
BPF Design Q&A
==============
BPF extensibility and applicability to networking, tracing, security
in the linux kernel and several user space implementations of BPF
virtual machine led to a number of misunderstanding on what BPF actually is.
This short QA is an attempt to address that and outline a dire... | Documentation/bpf/bpf_design_QA.rst | null | null | null | null | null |
source | linux | =================================
HOWTO interact with BPF subsystem
=================================
This document provides information for the BPF subsystem about various
workflows related to reporting bugs, submitting patches, and queueing
patches for stable kernels.
For general information about submitting patche... | Documentation/bpf/bpf_devel_QA.rst | null | null | null | null | null |
source | linux | =============
BPF Iterators
=============
--------
Overview
--------
BPF supports two separate entities collectively known as "BPF iterators": BPF
iterator *program type* and *open-coded* BPF iterators. The former is
a stand-alone BPF program type which, when attached and activated by user,
will be called once for ea... | Documentation/bpf/bpf_iterators.rst | null | null | null | null | null |
source | linux | =============
BPF licensing
=============
Background
==========
* Classic BPF was BSD licensed
"BPF" was originally introduced as BSD Packet Filter in
http://www.tcpdump.org/papers/bpf-usenix93.pdf. The corresponding instruction
set and its implementation came from BSD with BSD license. That original
instruction set... | Documentation/bpf/bpf_licensing.rst | null | null | null | null | null |
source | linux | .. SPDX-License-Identifier: GPL-2.0
===================================
Running BPF programs from userspace
===================================
This document describes the ``BPF_PROG_RUN`` facility for running BPF programs
from userspace.
.. contents::
:local:
:depth: 2
Overview
--------
The ``BPF_PROG_RU... | Documentation/bpf/bpf_prog_run.rst | null | null | null | null | null |
source | linux | =====================
BPF Type Format (BTF)
=====================
1. Introduction
===============
BTF (BPF Type Format) is the metadata format which encodes the debug info
related to BPF program/map. The name BTF was used initially to describe data
types. The BTF was later extended to include function info for define... | Documentation/bpf/btf.rst | null | null | null | null | null |
source | linux | .. contents::
.. sectnum::
==========================
Clang implementation notes
==========================
This document provides more details specific to the Clang/LLVM implementation of the eBPF instruction set.
Versions
========
Clang defined "CPU" versions, where a CPU version of 3 corresponds to the current e... | Documentation/bpf/clang-notes.rst | null | null | null | null | null |
source | linux | ===================
Classic BPF vs eBPF
===================
eBPF is designed to be JITed with one to one mapping, which can also open up
the possibility for GCC/LLVM compilers to generate optimized eBPF code through
an eBPF backend that performs almost as fast as natively compiled code.
Some core changes of the eBPF ... | Documentation/bpf/classic_vs_extended.rst | null | null | null | null | null |
source | linux | .. SPDX-License-Identifier: GPL-2.0
.. _cpumasks-header-label:
==================
BPF cpumask kfuncs
==================
1. Introduction
===============
``struct cpumask`` is a bitmap data structure in the kernel whose indices
reflect the CPUs on the system. Commonly, cpumasks are used to track which CPUs
a task is ... | Documentation/bpf/cpumasks.rst | null | null | null | null | null |
source | linux | .. SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
==============
BPF drgn tools
==============
drgn scripts is a convenient and easy to use mechanism to retrieve arbitrary
kernel data structures. drgn is not relying on kernel UAPI to read the data.
Instead it's reading directly from ``/proc/kcore`` or vmcore and... | Documentation/bpf/drgn.rst | null | null | null | null | null |
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