path: root/templates/man2/userfaultfd.2.pot

# SOME DESCRIPTIVE TITLE
# Copyright (C) YEAR Free Software Foundation, Inc.
# This file is distributed under the same license as the PACKAGE package.
# FIRST AUTHOR <EMAIL@ADDRESS>, YEAR.
#
#, fuzzy
msgid ""
msgstr ""
"Project-Id-Version: PACKAGE VERSION\n"
"POT-Creation-Date: 2024-06-01 06:33+0200\n"
"PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\n"
"Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
"Language-Team: LANGUAGE <LL@li.org>\n"
"Language: \n"
"MIME-Version: 1.0\n"
"Content-Type: text/plain; charset=UTF-8\n"
"Content-Transfer-Encoding: 8bit\n"

#. type: TH
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
#, no-wrap
msgid "userfaultfd"
msgstr ""

#. type: TH
#: archlinux debian-unstable opensuse-tumbleweed
#, no-wrap
msgid "2024-05-02"
msgstr ""

#. type: TH
#: archlinux debian-unstable
#, no-wrap
msgid "Linux man-pages 6.8"
msgstr ""

#. type: SH
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
#, no-wrap
msgid "NAME"
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid ""
"userfaultfd - create a file descriptor for handling page faults in user space"
msgstr ""

#. type: SH
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
#, no-wrap
msgid "LIBRARY"
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid "Standard C library (I<libc>, I<-lc>)"
msgstr ""

#. type: SH
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
#, no-wrap
msgid "SYNOPSIS"
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
#, no-wrap
msgid ""
"B<#include E<lt>fcntl.hE<gt>>             /* Definition of B<O_*> constants */\n"
"B<#include E<lt>sys/syscall.hE<gt>>       /* Definition of B<SYS_*> constants */\n"
"B<#include E<lt>linux/userfaultfd.hE<gt>> /* Definition of B<UFFD_*> constants */\n"
"B<#include E<lt>unistd.hE<gt>>\n"
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
#, no-wrap
msgid "B<int syscall(SYS_userfaultfd, int >I<flags>B<);>\n"
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid ""
"I<Note>: glibc provides no wrapper for B<userfaultfd>(), necessitating the "
"use of B<syscall>(2)."
msgstr ""

#. type: SH
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
#, no-wrap
msgid "DESCRIPTION"
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid ""
"B<userfaultfd>()  creates a new userfaultfd object that can be used for "
"delegation of page-fault handling to a user-space application, and returns a "
"file descriptor that refers to the new object.  The new userfaultfd object "
"is configured using B<ioctl>(2)."
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid ""
"Once the userfaultfd object is configured, the application can use "
"B<read>(2)  to receive userfaultfd notifications.  The reads from "
"userfaultfd may be blocking or non-blocking, depending on the value of "
"I<flags> used for the creation of the userfaultfd or subsequent calls to "
"B<fcntl>(2)."
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid ""
"The following values may be bitwise ORed in I<flags> to change the behavior "
"of B<userfaultfd>():"
msgstr ""

#. type: TP
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
#, no-wrap
msgid "B<O_CLOEXEC>"
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid ""
"Enable the close-on-exec flag for the new userfaultfd file descriptor.  See "
"the description of the B<O_CLOEXEC> flag in B<open>(2)."
msgstr ""

#. type: TP
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
#, no-wrap
msgid "B<O_NONBLOCK>"
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid ""
"Enables non-blocking operation for the userfaultfd object.  See the "
"description of the B<O_NONBLOCK> flag in B<open>(2)."
msgstr ""

#. type: TP
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
#, no-wrap
msgid "B<UFFD_USER_MODE_ONLY>"
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid ""
"This is an userfaultfd-specific flag that was introduced in Linux 5.11.  "
"When set, the userfaultfd object will only be able to handle page faults "
"originated from the user space on the registered regions.  When a kernel-"
"originated fault was triggered on the registered range with this "
"userfaultfd, a B<SIGBUS> signal will be delivered."
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid ""
"When the last file descriptor referring to a userfaultfd object is closed, "
"all memory ranges that were registered with the object are unregistered and "
"unread events are flushed."
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid "Userfaultfd supports three modes of registration:"
msgstr ""

#. type: TP
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
#, no-wrap
msgid "B<UFFDIO_REGISTER_MODE_MISSING> (since Linux 4.10)"
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid ""
"When registered with B<UFFDIO_REGISTER_MODE_MISSING> mode, user-space will "
"receive a page-fault notification when a missing page is accessed.  The "
"faulted thread will be stopped from execution until the page fault is "
"resolved from user-space by either an B<UFFDIO_COPY> or an "
"B<UFFDIO_ZEROPAGE> ioctl."
msgstr ""

#. type: TP
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
#, no-wrap
msgid "B<UFFDIO_REGISTER_MODE_MINOR> (since Linux 5.13)"
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid ""
"When registered with B<UFFDIO_REGISTER_MODE_MINOR> mode, user-space will "
"receive a page-fault notification when a minor page fault occurs.  That is, "
"when a backing page is in the page cache, but page table entries don't yet "
"exist.  The faulted thread will be stopped from execution until the page "
"fault is resolved from user-space by an B<UFFDIO_CONTINUE> ioctl."
msgstr ""

#. type: TP
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
#, no-wrap
msgid "B<UFFDIO_REGISTER_MODE_WP> (since Linux 5.7)"
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid ""
"When registered with B<UFFDIO_REGISTER_MODE_WP> mode, user-space will "
"receive a page-fault notification when a write-protected page is written.  "
"The faulted thread will be stopped from execution until user-space write-"
"unprotects the page using an B<UFFDIO_WRITEPROTECT> ioctl."
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid ""
"Multiple modes can be enabled at the same time for the same memory range."
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid ""
"Since Linux 4.14, a userfaultfd page-fault notification can selectively "
"embed faulting thread ID information into the notification.  One needs to "
"enable this feature explicitly using the B<UFFD_FEATURE_THREAD_ID> feature "
"bit when initializing the userfaultfd context.  By default, thread ID "
"reporting is disabled."
msgstr ""

#. type: SS
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
#, no-wrap
msgid "Usage"
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid ""
"The userfaultfd mechanism is designed to allow a thread in a multithreaded "
"program to perform user-space paging for the other threads in the process.  "
"When a page fault occurs for one of the regions registered to the "
"userfaultfd object, the faulting thread is put to sleep and an event is "
"generated that can be read via the userfaultfd file descriptor.  The fault-"
"handling thread reads events from this file descriptor and services them "
"using the operations described in B<ioctl_userfaultfd>(2).  When servicing "
"the page fault events, the fault-handling thread can trigger a wake-up for "
"the sleeping thread."
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid ""
"It is possible for the faulting threads and the fault-handling threads to "
"run in the context of different processes.  In this case, these threads may "
"belong to different programs, and the program that executes the faulting "
"threads will not necessarily cooperate with the program that handles the "
"page faults.  In such non-cooperative mode, the process that monitors "
"userfaultfd and handles page faults needs to be aware of the changes in the "
"virtual memory layout of the faulting process to avoid memory corruption."
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid ""
"Since Linux 4.11, userfaultfd can also notify the fault-handling threads "
"about changes in the virtual memory layout of the faulting process.  In "
"addition, if the faulting process invokes B<fork>(2), the userfaultfd "
"objects associated with the parent may be duplicated into the child process "
"and the userfaultfd monitor will be notified (via the B<UFFD_EVENT_FORK> "
"described below)  about the file descriptor associated with the userfault "
"objects created for the child process, which allows the userfaultfd monitor "
"to perform user-space paging for the child process.  Unlike page faults "
"which have to be synchronous and require an explicit or implicit wakeup, all "
"other events are delivered asynchronously and the non-cooperative process "
"resumes execution as soon as the userfaultfd manager executes B<read>(2).  "
"The userfaultfd manager should carefully synchronize calls to B<UFFDIO_COPY> "
"with the processing of events."
msgstr ""

#. #-#-#-#-#  archlinux: userfaultfd.2.pot (PACKAGE VERSION)  #-#-#-#-#
#.  Regarding the preceding sentence, Mike Rapoport says:
#.      The major point here is that current events delivery model could be
#.      problematic for multi-threaded monitor. I even suspect that it would be
#.      impossible to ensure synchronization between page faults and non-page
#.      fault events in multi-threaded monitor.
#.  .P
#.  FIXME elaborate about non-cooperating mode, describe its limitations
#.  for kernels before Linux 4.11, features added in Linux 4.11
#.  and limitations remaining in Linux 4.11
#.  Maybe it's worth adding a dedicated sub-section...
#. type: Plain text
#. #-#-#-#-#  debian-bookworm: userfaultfd.2.pot (PACKAGE VERSION)  #-#-#-#-#
#.  Regarding the preceding sentence, Mike Rapoport says:
#.      The major point here is that current events delivery model could be
#.      problematic for multi-threaded monitor. I even suspect that it would be
#.      impossible to ensure synchronization between page faults and non-page
#.      fault events in multi-threaded monitor.
#.  .PP
#.  FIXME elaborate about non-cooperating mode, describe its limitations
#.  for kernels before Linux 4.11, features added in Linux 4.11
#.  and limitations remaining in Linux 4.11
#.  Maybe it's worth adding a dedicated sub-section...
#. type: Plain text
#. #-#-#-#-#  debian-unstable: userfaultfd.2.pot (PACKAGE VERSION)  #-#-#-#-#
#.  Regarding the preceding sentence, Mike Rapoport says:
#.      The major point here is that current events delivery model could be
#.      problematic for multi-threaded monitor. I even suspect that it would be
#.      impossible to ensure synchronization between page faults and non-page
#.      fault events in multi-threaded monitor.
#.  .P
#.  FIXME elaborate about non-cooperating mode, describe its limitations
#.  for kernels before Linux 4.11, features added in Linux 4.11
#.  and limitations remaining in Linux 4.11
#.  Maybe it's worth adding a dedicated sub-section...
#. type: Plain text
#. #-#-#-#-#  fedora-40: userfaultfd.2.pot (PACKAGE VERSION)  #-#-#-#-#
#.  Regarding the preceding sentence, Mike Rapoport says:
#.      The major point here is that current events delivery model could be
#.      problematic for multi-threaded monitor. I even suspect that it would be
#.      impossible to ensure synchronization between page faults and non-page
#.      fault events in multi-threaded monitor.
#.  .P
#.  FIXME elaborate about non-cooperating mode, describe its limitations
#.  for kernels before Linux 4.11, features added in Linux 4.11
#.  and limitations remaining in Linux 4.11
#.  Maybe it's worth adding a dedicated sub-section...
#. type: Plain text
#. #-#-#-#-#  fedora-rawhide: userfaultfd.2.pot (PACKAGE VERSION)  #-#-#-#-#
#.  Regarding the preceding sentence, Mike Rapoport says:
#.      The major point here is that current events delivery model could be
#.      problematic for multi-threaded monitor. I even suspect that it would be
#.      impossible to ensure synchronization between page faults and non-page
#.      fault events in multi-threaded monitor.
#.  .P
#.  FIXME elaborate about non-cooperating mode, describe its limitations
#.  for kernels before Linux 4.11, features added in Linux 4.11
#.  and limitations remaining in Linux 4.11
#.  Maybe it's worth adding a dedicated sub-section...
#. type: Plain text
#. #-#-#-#-#  mageia-cauldron: userfaultfd.2.pot (PACKAGE VERSION)  #-#-#-#-#
#.  Regarding the preceding sentence, Mike Rapoport says:
#.      The major point here is that current events delivery model could be
#.      problematic for multi-threaded monitor. I even suspect that it would be
#.      impossible to ensure synchronization between page faults and non-page
#.      fault events in multi-threaded monitor.
#.  .P
#.  FIXME elaborate about non-cooperating mode, describe its limitations
#.  for kernels before Linux 4.11, features added in Linux 4.11
#.  and limitations remaining in Linux 4.11
#.  Maybe it's worth adding a dedicated sub-section...
#. type: Plain text
#. #-#-#-#-#  opensuse-leap-15-6: userfaultfd.2.pot (PACKAGE VERSION)  #-#-#-#-#
#.  Regarding the preceding sentence, Mike Rapoport says:
#.      The major point here is that current events delivery model could be
#.      problematic for multi-threaded monitor. I even suspect that it would be
#.      impossible to ensure synchronization between page faults and non-page
#.      fault events in multi-threaded monitor.
#.  .PP
#.  FIXME elaborate about non-cooperating mode, describe its limitations
#.  for kernels before Linux 4.11, features added in Linux 4.11
#.  and limitations remaining in Linux 4.11
#.  Maybe it's worth adding a dedicated sub-section...
#. type: Plain text
#. #-#-#-#-#  opensuse-tumbleweed: userfaultfd.2.pot (PACKAGE VERSION)  #-#-#-#-#
#.  Regarding the preceding sentence, Mike Rapoport says:
#.      The major point here is that current events delivery model could be
#.      problematic for multi-threaded monitor. I even suspect that it would be
#.      impossible to ensure synchronization between page faults and non-page
#.      fault events in multi-threaded monitor.
#.  .P
#.  FIXME elaborate about non-cooperating mode, describe its limitations
#.  for kernels before Linux 4.11, features added in Linux 4.11
#.  and limitations remaining in Linux 4.11
#.  Maybe it's worth adding a dedicated sub-section...
#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid ""
"The current asynchronous model of the event delivery is optimal for single "
"threaded non-cooperative userfaultfd manager implementations."
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid ""
"Since Linux 5.7, userfaultfd is able to do synchronous page dirty tracking "
"using the new write-protect register mode.  One should check against the "
"feature bit B<UFFD_FEATURE_PAGEFAULT_FLAG_WP> before using this feature.  "
"Similar to the original userfaultfd missing mode, the write-protect mode "
"will generate a userfaultfd notification when the protected page is "
"written.  The user needs to resolve the page fault by unprotecting the "
"faulted page and kicking the faulted thread to continue.  For more "
"information, please refer to the \"Userfaultfd write-protect mode\" section."
msgstr ""

#. type: SS
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
#, no-wrap
msgid "Userfaultfd operation"
msgstr ""

#. type: Plain text
#: archlinux debian-unstable fedora-40 fedora-rawhide mageia-cauldron
#: opensuse-tumbleweed
msgid ""
"After the userfaultfd object is created with B<userfaultfd>(), the "
"application must enable it using the B<UFFDIO_API> B<ioctl>(2)  operation.  "
"This operation allows a two-step handshake between the kernel and user space "
"to determine what API version and features the kernel supports, and then to "
"enable those features user space wants.  This operation must be performed "
"before any of the other B<ioctl>(2)  operations described below (or those "
"operations fail with the B<EINVAL> error)."
msgstr ""

#. type: Plain text
#: archlinux debian-unstable fedora-40 fedora-rawhide mageia-cauldron
#: opensuse-tumbleweed
msgid ""
"After a successful B<UFFDIO_API> operation, the application then registers "
"memory address ranges using the B<UFFDIO_REGISTER> B<ioctl>(2)  operation.  "
"After successful completion of a B<UFFDIO_REGISTER> operation, a page fault "
"occurring in the requested memory range, and satisfying the mode defined at "
"the registration time, will be forwarded by the kernel to the user-space "
"application.  The application can then use various (e.g., B<UFFDIO_COPY>, "
"B<UFFDIO_ZEROPAGE>, or B<UFFDIO_CONTINUE>)  B<ioctl>(2)  operations to "
"resolve the page fault."
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid ""
"Since Linux 4.14, if the application sets the B<UFFD_FEATURE_SIGBUS> feature "
"bit using the B<UFFDIO_API> B<ioctl>(2), no page-fault notification will be "
"forwarded to user space.  Instead a B<SIGBUS> signal is delivered to the "
"faulting process.  With this feature, userfaultfd can be used for robustness "
"purposes to simply catch any access to areas within the registered address "
"range that do not have pages allocated, without having to listen to "
"userfaultfd events.  No userfaultfd monitor will be required for dealing "
"with such memory accesses.  For example, this feature can be useful for "
"applications that want to prevent the kernel from automatically allocating "
"pages and filling holes in sparse files when the hole is accessed through a "
"memory mapping."
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid ""
"The B<UFFD_FEATURE_SIGBUS> feature is implicitly inherited through "
"B<fork>(2)  if used in combination with B<UFFD_FEATURE_FORK>."
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid ""
"Details of the various B<ioctl>(2)  operations can be found in "
"B<ioctl_userfaultfd>(2)."
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid ""
"Since Linux 4.11, events other than page-fault may enabled during "
"B<UFFDIO_API> operation."
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid ""
"Up to Linux 4.11, userfaultfd can be used only with anonymous private memory "
"mappings.  Since Linux 4.11, userfaultfd can be also used with hugetlbfs and "
"shared memory mappings."
msgstr ""

#. type: SS
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
#, no-wrap
msgid "Userfaultfd write-protect mode (since Linux 5.7)"
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid ""
"Since Linux 5.7, userfaultfd supports write-protect mode for anonymous "
"memory.  The user needs to first check availability of this feature using "
"B<UFFDIO_API> ioctl against the feature bit "
"B<UFFD_FEATURE_PAGEFAULT_FLAG_WP> before using this feature."
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid ""
"Since Linux 5.19, the write-protection mode was also supported on shmem and "
"hugetlbfs memory types.  It can be detected with the feature bit "
"B<UFFD_FEATURE_WP_HUGETLBFS_SHMEM>."
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid ""
"To register with userfaultfd write-protect mode, the user needs to initiate "
"the B<UFFDIO_REGISTER> ioctl with mode B<UFFDIO_REGISTER_MODE_WP> set.  Note "
"that it is legal to monitor the same memory range with multiple modes.  For "
"example, the user can do B<UFFDIO_REGISTER> with the mode set to "
"B<UFFDIO_REGISTER_MODE_MISSING | UFFDIO_REGISTER_MODE_WP>.  When there is "
"only B<UFFDIO_REGISTER_MODE_WP> registered, user-space will I<not> receive "
"any notification when a missing page is written.  Instead, user-space will "
"receive a write-protect page-fault notification only when an existing but "
"write-protected page got written."
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid ""
"After the B<UFFDIO_REGISTER> ioctl completed with B<UFFDIO_REGISTER_MODE_WP> "
"mode set, the user can write-protect any existing memory within the range "
"using the ioctl B<UFFDIO_WRITEPROTECT> where I<uffdio_writeprotect.mode> "
"should be set to B<UFFDIO_WRITEPROTECT_MODE_WP>."
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid ""
"When a write-protect event happens, user-space will receive a page-fault "
"notification whose I<uffd_msg.pagefault.flags> will be with "
"B<UFFD_PAGEFAULT_FLAG_WP> flag set.  Note: since only writes can trigger "
"this kind of fault, write-protect notifications will always have the "
"B<UFFD_PAGEFAULT_FLAG_WRITE> bit set along with the "
"B<UFFD_PAGEFAULT_FLAG_WP> bit."
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid ""
"To resolve a write-protection page fault, the user should initiate another "
"B<UFFDIO_WRITEPROTECT> ioctl, whose I<uffd_msg.pagefault.flags> should have "
"the flag B<UFFDIO_WRITEPROTECT_MODE_WP> cleared upon the faulted page or "
"range."
msgstr ""

#. type: SS
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
#, no-wrap
msgid "Userfaultfd minor fault mode (since Linux 5.13)"
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid ""
"Since Linux 5.13, userfaultfd supports minor fault mode.  In this mode, "
"fault messages are produced not for major faults (where the page was "
"missing), but rather for minor faults, where a page exists in the page "
"cache, but the page table entries are not yet present.  The user needs to "
"first check availability of this feature using the B<UFFDIO_API> ioctl with "
"the appropriate feature bits set before using this feature: "
"B<UFFD_FEATURE_MINOR_HUGETLBFS> since Linux 5.13, or "
"B<UFFD_FEATURE_MINOR_SHMEM> since Linux 5.14."
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid ""
"To register with userfaultfd minor fault mode, the user needs to initiate "
"the B<UFFDIO_REGISTER> ioctl with mode B<UFFD_REGISTER_MODE_MINOR> set."
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid ""
"When a minor fault occurs, user-space will receive a page-fault notification "
"whose I<uffd_msg.pagefault.flags> will have the B<UFFD_PAGEFAULT_FLAG_MINOR> "
"flag set."
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid ""
"To resolve a minor page fault, the handler should decide whether or not the "
"existing page contents need to be modified first.  If so, this should be "
"done in-place via a second, non-userfaultfd-registered mapping to the same "
"backing page (e.g., by mapping the shmem or hugetlbfs file twice).  Once the "
"page is considered \"up to date\", the fault can be resolved by initiating "
"an B<UFFDIO_CONTINUE> ioctl, which installs the page table entries and (by "
"default)  wakes up the faulting thread(s)."
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid ""
"Minor fault mode supports only hugetlbfs-backed (since Linux 5.13)  and "
"shmem-backed (since Linux 5.14) memory."
msgstr ""

#. type: SS
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
#, no-wrap
msgid "Reading from the userfaultfd structure"
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid ""
"Each B<read>(2)  from the userfaultfd file descriptor returns one or more "
"I<uffd_msg> structures, each of which describes a page-fault event or an "
"event required for the non-cooperative userfaultfd usage:"
msgstr ""

#. type: Plain text
#: archlinux debian-unstable fedora-40 fedora-rawhide mageia-cauldron
#: opensuse-tumbleweed
#, no-wrap
msgid ""
"struct uffd_msg {\n"
"    __u8  event;            /* Type of event */\n"
"    ...\n"
"    union {\n"
"        struct {\n"
"            __u64 flags;    /* Flags describing fault */\n"
"            __u64 address;  /* Faulting address */\n"
"            union {\n"
"                __u32 ptid; /* Thread ID of the fault */\n"
"            } feat;\n"
"        } pagefault;\n"
"\\&\n"
"        struct {            /* Since Linux 4.11 */\n"
"            __u32 ufd;      /* Userfault file descriptor\n"
"                               of the child process */\n"
"        } fork;\n"
"\\&\n"
"        struct {            /* Since Linux 4.11 */\n"
"            __u64 from;     /* Old address of remapped area */\n"
"            __u64 to;       /* New address of remapped area */\n"
"            __u64 len;      /* Original mapping length */\n"
"        } remap;\n"
"\\&\n"
"        struct {            /* Since Linux 4.11 */\n"
"            __u64 start;    /* Start address of removed area */\n"
"            __u64 end;      /* End address of removed area */\n"
"        } remove;\n"
"        ...\n"
"    } arg;\n"
"\\&\n"
"    /* Padding fields omitted */\n"
"} __packed;\n"
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid ""
"If multiple events are available and the supplied buffer is large enough, "
"B<read>(2)  returns as many events as will fit in the supplied buffer.  If "
"the buffer supplied to B<read>(2)  is smaller than the size of the "
"I<uffd_msg> structure, the B<read>(2)  fails with the error B<EINVAL>."
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid "The fields set in the I<uffd_msg> structure are as follows:"
msgstr ""

#. type: TP
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
#, no-wrap
msgid "I<event>"
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid ""
"The type of event.  Depending of the event type, different fields of the "
"I<arg> union represent details required for the event processing.  The non-"
"page-fault events are generated only when appropriate feature is enabled "
"during API handshake with B<UFFDIO_API> B<ioctl>(2)."
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid "The following values can appear in the I<event> field:"
msgstr ""

#. type: TP
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
#, no-wrap
msgid "B<UFFD_EVENT_PAGEFAULT> (since Linux 4.3)"
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid ""
"A page-fault event.  The page-fault details are available in the "
"I<pagefault> field."
msgstr ""

#. type: TP
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
#, no-wrap
msgid "B<UFFD_EVENT_FORK> (since Linux 4.11)"
msgstr ""

#.  FIXME describe duplication of userfault file descriptor during fork
#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid ""
"Generated when the faulting process invokes B<fork>(2)  (or B<clone>(2)  "
"without the B<CLONE_VM> flag).  The event details are available in the "
"I<fork> field."
msgstr ""

#. type: TP
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
#, no-wrap
msgid "B<UFFD_EVENT_REMAP> (since Linux 4.11)"
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid ""
"Generated when the faulting process invokes B<mremap>(2).  The event details "
"are available in the I<remap> field."
msgstr ""

#. type: TP
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
#, no-wrap
msgid "B<UFFD_EVENT_REMOVE> (since Linux 4.11)"
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid ""
"Generated when the faulting process invokes B<madvise>(2)  with "
"B<MADV_DONTNEED> or B<MADV_REMOVE> advice.  The event details are available "
"in the I<remove> field."
msgstr ""

#. type: TP
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
#, no-wrap
msgid "B<UFFD_EVENT_UNMAP> (since Linux 4.11)"
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid ""
"Generated when the faulting process unmaps a memory range, either explicitly "
"using B<munmap>(2)  or implicitly during B<mmap>(2)  or B<mremap>(2).  The "
"event details are available in the I<remove> field."
msgstr ""

#. type: TP
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
#, no-wrap
msgid "I<pagefault.address>"
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid "The address that triggered the page fault."
msgstr ""

#. type: TP
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
#, no-wrap
msgid "I<pagefault.flags>"
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid ""
"A bit mask of flags that describe the event.  For B<UFFD_EVENT_PAGEFAULT>, "
"the following flag may appear:"
msgstr ""

#. type: TP
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
#, no-wrap
msgid "B<UFFD_PAGEFAULT_FLAG_WP>"
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid "If this flag is set, then the fault was a write-protect fault."
msgstr ""

#. type: TP
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
#, no-wrap
msgid "B<UFFD_PAGEFAULT_FLAG_MINOR>"
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid "If this flag is set, then the fault was a minor fault."
msgstr ""

#. type: TP
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
#, no-wrap
msgid "B<UFFD_PAGEFAULT_FLAG_WRITE>"
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid "If this flag is set, then the fault was a write fault."
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid ""
"If neither B<UFFD_PAGEFAULT_FLAG_WP> nor B<UFFD_PAGEFAULT_FLAG_MINOR> are "
"set, then the fault was a missing fault."
msgstr ""

#. type: TP
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
#, no-wrap
msgid "I<pagefault.feat.pid>"
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid "The thread ID that triggered the page fault."
msgstr ""

#. type: TP
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
#, no-wrap
msgid "I<fork.ufd>"
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid ""
"The file descriptor associated with the userfault object created for the "
"child created by B<fork>(2)."
msgstr ""

#. type: TP
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
#, no-wrap
msgid "I<remap.from>"
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid ""
"The original address of the memory range that was remapped using "
"B<mremap>(2)."
msgstr ""

#. type: TP
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
#, no-wrap
msgid "I<remap.to>"
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid ""
"The new address of the memory range that was remapped using B<mremap>(2)."
msgstr ""

#. type: TP
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
#, no-wrap
msgid "I<remap.len>"
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid ""
"The original length of the memory range that was remapped using B<mremap>(2)."
msgstr ""

#. type: TP
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
#, no-wrap
msgid "I<remove.start>"
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid ""
"The start address of the memory range that was freed using B<madvise>(2)  or "
"unmapped"
msgstr ""

#. type: TP
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
#, no-wrap
msgid "I<remove.end>"
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid ""
"The end address of the memory range that was freed using B<madvise>(2)  or "
"unmapped"
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid ""
"A B<read>(2)  on a userfaultfd file descriptor can fail with the following "
"errors:"
msgstr ""

#. type: TP
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
#, no-wrap
msgid "B<EINVAL>"
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid ""
"The userfaultfd object has not yet been enabled using the B<UFFDIO_API> "
"B<ioctl>(2)  operation"
msgstr ""

#.  FIXME What is the reason for this seemingly odd behavior with respect
#.  to the O_NONBLOCK flag? (see userfaultfd_poll() in fs/userfaultfd.c).
#.  Something needs to be said about this.
#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid ""
"If the B<O_NONBLOCK> flag is enabled in the associated open file "
"description, the userfaultfd file descriptor can be monitored with "
"B<poll>(2), B<select>(2), and B<epoll>(7).  When events are available, the "
"file descriptor indicates as readable.  If the B<O_NONBLOCK> flag is not "
"enabled, then B<poll>(2)  (always) indicates the file as having a B<POLLERR> "
"condition, and B<select>(2)  indicates the file descriptor as both readable "
"and writable."
msgstr ""

#. type: SH
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
#, no-wrap
msgid "RETURN VALUE"
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid ""
"On success, B<userfaultfd>()  returns a new file descriptor that refers to "
"the userfaultfd object.  On error, -1 is returned, and I<errno> is set to "
"indicate the error."
msgstr ""

#. type: SH
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
#, no-wrap
msgid "ERRORS"
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid "An unsupported value was specified in I<flags>."
msgstr ""

#. type: TP
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
#, no-wrap
msgid "B<EMFILE>"
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid ""
"The per-process limit on the number of open file descriptors has been reached"
msgstr ""

#. type: TP
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
#, no-wrap
msgid "B<ENFILE>"
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid ""
"The system-wide limit on the total number of open files has been reached."
msgstr ""

#. type: TP
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
#, no-wrap
msgid "B<ENOMEM>"
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid "Insufficient kernel memory was available."
msgstr ""

#. type: TP
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
#, no-wrap
msgid "B<EPERM> (since Linux 5.2)"
msgstr ""

#.  cefdca0a86be517bc390fc4541e3674b8e7803b0
#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid ""
"The caller is not privileged (does not have the B<CAP_SYS_PTRACE> capability "
"in the initial user namespace), and I</proc/sys/vm/unprivileged_userfaultfd> "
"has the value 0."
msgstr ""

#. type: SH
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
#, no-wrap
msgid "STANDARDS"
msgstr ""

#. type: Plain text
#: archlinux debian-unstable fedora-40 fedora-rawhide mageia-cauldron
#: opensuse-leap-15-6 opensuse-tumbleweed
msgid "Linux."
msgstr ""

#. type: SH
#: archlinux debian-unstable fedora-40 fedora-rawhide mageia-cauldron
#: opensuse-leap-15-6 opensuse-tumbleweed
#, no-wrap
msgid "HISTORY"
msgstr ""

#. type: Plain text
#: archlinux debian-unstable fedora-40 fedora-rawhide mageia-cauldron
#: opensuse-leap-15-6 opensuse-tumbleweed
msgid "Linux 4.3."
msgstr ""

#. type: Plain text
#: archlinux debian-unstable fedora-40 fedora-rawhide mageia-cauldron
#: opensuse-leap-15-6 opensuse-tumbleweed
msgid ""
"Support for hugetlbfs and shared memory areas and non-page-fault events was "
"added in Linux 4.11"
msgstr ""

#. type: SH
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
#, no-wrap
msgid "NOTES"
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid ""
"The userfaultfd mechanism can be used as an alternative to traditional user-"
"space paging techniques based on the use of the B<SIGSEGV> signal and "
"B<mmap>(2).  It can also be used to implement lazy restore for checkpoint/"
"restore mechanisms, as well as post-copy migration to allow (nearly) "
"uninterrupted execution when transferring virtual machines and Linux "
"containers from one host to another."
msgstr ""

#. type: SH
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
#, no-wrap
msgid "BUGS"
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid ""
"If the B<UFFD_FEATURE_EVENT_FORK> is enabled and a system call from the "
"B<fork>(2)  family is interrupted by a signal or failed, a stale userfaultfd "
"descriptor might be created.  In this case, a spurious B<UFFD_EVENT_FORK> "
"will be delivered to the userfaultfd monitor."
msgstr ""

#. type: SH
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
#, no-wrap
msgid "EXAMPLES"
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid ""
"The program below demonstrates the use of the userfaultfd mechanism.  The "
"program creates two threads, one of which acts as the page-fault handler for "
"the process, for the pages in a demand-page zero region created using "
"B<mmap>(2)."
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid ""
"The program takes one command-line argument, which is the number of pages "
"that will be created in a mapping whose page faults will be handled via "
"userfaultfd.  After creating a userfaultfd object, the program then creates "
"an anonymous private mapping of the specified size and registers the address "
"range of that mapping using the B<UFFDIO_REGISTER> B<ioctl>(2)  operation.  "
"The program then creates a second thread that will perform the task of "
"handling page faults."
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid ""
"The main thread then walks through the pages of the mapping fetching bytes "
"from successive pages.  Because the pages have not yet been accessed, the "
"first access of a byte in each page will trigger a page-fault event on the "
"userfaultfd file descriptor."
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid ""
"Each of the page-fault events is handled by the second thread, which sits in "
"a loop processing input from the userfaultfd file descriptor.  In each loop "
"iteration, the second thread first calls B<poll>(2)  to check the state of "
"the file descriptor, and then reads an event from the file descriptor.  All "
"such events should be B<UFFD_EVENT_PAGEFAULT> events, which the thread "
"handles by copying a page of data into the faulting region using the "
"B<UFFDIO_COPY> B<ioctl>(2)  operation."
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid "The following is an example of what we see when running the program:"
msgstr ""

#. type: Plain text
#: archlinux debian-unstable fedora-40 fedora-rawhide mageia-cauldron
#: opensuse-tumbleweed
#, no-wrap
msgid ""
"$ B<./userfaultfd_demo 3>\n"
"Address returned by mmap() = 0x7fd30106c000\n"
"\\&\n"
"fault_handler_thread():\n"
"    poll() returns: nready = 1; POLLIN = 1; POLLERR = 0\n"
"    UFFD_EVENT_PAGEFAULT event: flags = 0; address = 7fd30106c00f\n"
"        (uffdio_copy.copy returned 4096)\n"
"Read address 0x7fd30106c00f in main(): A\n"
"Read address 0x7fd30106c40f in main(): A\n"
"Read address 0x7fd30106c80f in main(): A\n"
"Read address 0x7fd30106cc0f in main(): A\n"
"\\&\n"
"fault_handler_thread():\n"
"    poll() returns: nready = 1; POLLIN = 1; POLLERR = 0\n"
"    UFFD_EVENT_PAGEFAULT event: flags = 0; address = 7fd30106d00f\n"
"        (uffdio_copy.copy returned 4096)\n"
"Read address 0x7fd30106d00f in main(): B\n"
"Read address 0x7fd30106d40f in main(): B\n"
"Read address 0x7fd30106d80f in main(): B\n"
"Read address 0x7fd30106dc0f in main(): B\n"
"\\&\n"
"fault_handler_thread():\n"
"    poll() returns: nready = 1; POLLIN = 1; POLLERR = 0\n"
"    UFFD_EVENT_PAGEFAULT event: flags = 0; address = 7fd30106e00f\n"
"        (uffdio_copy.copy returned 4096)\n"
"Read address 0x7fd30106e00f in main(): C\n"
"Read address 0x7fd30106e40f in main(): C\n"
"Read address 0x7fd30106e80f in main(): C\n"
"Read address 0x7fd30106ec0f in main(): C\n"
msgstr ""

#. type: SS
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
#, no-wrap
msgid "Program source"
msgstr ""

#. type: Plain text
#: archlinux debian-unstable fedora-40 fedora-rawhide mageia-cauldron
#: opensuse-tumbleweed
#, no-wrap
msgid ""
"/* userfaultfd_demo.c\n"
"\\&\n"
"   Licensed under the GNU General Public License version 2 or later.\n"
"*/\n"
"#define _GNU_SOURCE\n"
"#include E<lt>err.hE<gt>\n"
"#include E<lt>errno.hE<gt>\n"
"#include E<lt>fcntl.hE<gt>\n"
"#include E<lt>inttypes.hE<gt>\n"
"#include E<lt>linux/userfaultfd.hE<gt>\n"
"#include E<lt>poll.hE<gt>\n"
"#include E<lt>pthread.hE<gt>\n"
"#include E<lt>stdio.hE<gt>\n"
"#include E<lt>stdlib.hE<gt>\n"
"#include E<lt>string.hE<gt>\n"
"#include E<lt>sys/ioctl.hE<gt>\n"
"#include E<lt>sys/mman.hE<gt>\n"
"#include E<lt>sys/syscall.hE<gt>\n"
"#include E<lt>unistd.hE<gt>\n"
"\\&\n"
"static int page_size;\n"
"\\&\n"
"static void *\n"
"fault_handler_thread(void *arg)\n"
"{\n"
"    int                 nready;\n"
"    long                uffd;   /* userfaultfd file descriptor */\n"
"    ssize_t             nread;\n"
"    struct pollfd       pollfd;\n"
"    struct uffdio_copy  uffdio_copy;\n"
"\\&\n"
"    static int      fault_cnt = 0; /* Number of faults so far handled */\n"
"    static char     *page = NULL;\n"
"    static struct uffd_msg  msg;  /* Data read from userfaultfd */\n"
"\\&\n"
"    uffd = (long) arg;\n"
"\\&\n"
"    /* Create a page that will be copied into the faulting region. */\n"
"\\&\n"
"    if (page == NULL) {\n"
"        page = mmap(NULL, page_size, PROT_READ | PROT_WRITE,\n"
"                    MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);\n"
"        if (page == MAP_FAILED)\n"
"            err(EXIT_FAILURE, \"mmap\");\n"
"    }\n"
"\\&\n"
"    /* Loop, handling incoming events on the userfaultfd\n"
"       file descriptor. */\n"
"\\&\n"
"    for (;;) {\n"
"\\&\n"
"        /* See what poll() tells us about the userfaultfd. */\n"
"\\&\n"
"        pollfd.fd = uffd;\n"
"        pollfd.events = POLLIN;\n"
"        nready = poll(&pollfd, 1, -1);\n"
"        if (nready == -1)\n"
"            err(EXIT_FAILURE, \"poll\");\n"
"\\&\n"
"        printf(\"\\enfault_handler_thread():\\en\");\n"
"        printf(\"    poll() returns: nready = %d; \"\n"
"               \"POLLIN = %d; POLLERR = %d\\en\", nready,\n"
"               (pollfd.revents & POLLIN) != 0,\n"
"               (pollfd.revents & POLLERR) != 0);\n"
"\\&\n"
"        /* Read an event from the userfaultfd. */\n"
"\\&\n"
"        nread = read(uffd, &msg, sizeof(msg));\n"
"        if (nread == 0) {\n"
"            printf(\"EOF on userfaultfd!\\en\");\n"
"            exit(EXIT_FAILURE);\n"
"        }\n"
"\\&\n"
"        if (nread == -1)\n"
"            err(EXIT_FAILURE, \"read\");\n"
"\\&\n"
"        /* We expect only one kind of event; verify that assumption. */\n"
"\\&\n"
"        if (msg.event != UFFD_EVENT_PAGEFAULT) {\n"
"            fprintf(stderr, \"Unexpected event on userfaultfd\\en\");\n"
"            exit(EXIT_FAILURE);\n"
"        }\n"
"\\&\n"
"        /* Display info about the page-fault event. */\n"
"\\&\n"
"        printf(\"    UFFD_EVENT_PAGEFAULT event: \");\n"
"        printf(\"flags = %\"PRIx64\"; \", msg.arg.pagefault.flags);\n"
"        printf(\"address = %\"PRIx64\"\\en\", msg.arg.pagefault.address);\n"
"\\&\n"
"        /* Copy the page pointed to by \\[aq]page\\[aq] into the faulting\n"
"           region. Vary the contents that are copied in, so that it\n"
"           is more obvious that each fault is handled separately. */\n"
"\\&\n"
"        memset(page, \\[aq]A\\[aq] + fault_cnt % 20, page_size);\n"
"        fault_cnt++;\n"
"\\&\n"
"        uffdio_copy.src = (unsigned long) page;\n"
"\\&\n"
"        /* We need to handle page faults in units of pages(!).\n"
"           So, round faulting address down to page boundary. */\n"
"\\&\n"
"        uffdio_copy.dst = (unsigned long) msg.arg.pagefault.address &\n"
"                                           \\[ti](page_size - 1);\n"
"        uffdio_copy.len = page_size;\n"
"        uffdio_copy.mode = 0;\n"
"        uffdio_copy.copy = 0;\n"
"        if (ioctl(uffd, UFFDIO_COPY, &uffdio_copy) == -1)\n"
"            err(EXIT_FAILURE, \"ioctl-UFFDIO_COPY\");\n"
"\\&\n"
"        printf(\"        (uffdio_copy.copy returned %\"PRId64\")\\en\",\n"
"               uffdio_copy.copy);\n"
"    }\n"
"}\n"
"\\&\n"
"int\n"
"main(int argc, char *argv[])\n"
"{\n"
"    int        s;\n"
"    char       c;\n"
"    char       *addr;   /* Start of region handled by userfaultfd */\n"
"    long       uffd;    /* userfaultfd file descriptor */\n"
"    size_t     len, l;  /* Length of region handled by userfaultfd */\n"
"    pthread_t  thr;     /* ID of thread that handles page faults */\n"
"    struct uffdio_api       uffdio_api;\n"
"    struct uffdio_register  uffdio_register;\n"
"\\&\n"
"    if (argc != 2) {\n"
"        fprintf(stderr, \"Usage: %s num-pages\\en\", argv[0]);\n"
"        exit(EXIT_FAILURE);\n"
"    }\n"
"\\&\n"
"    page_size = sysconf(_SC_PAGE_SIZE);\n"
"    len = strtoull(argv[1], NULL, 0) * page_size;\n"
"\\&\n"
"    /* Create and enable userfaultfd object. */\n"
"\\&\n"
"    uffd = syscall(SYS_userfaultfd, O_CLOEXEC | O_NONBLOCK);\n"
"    if (uffd == -1)\n"
"        err(EXIT_FAILURE, \"userfaultfd\");\n"
"\\&\n"
"    /* NOTE: Two-step feature handshake is not needed here, since this\n"
"       example doesn't require any specific features.\n"
"\\&\n"
"       Programs that *do* should call UFFDIO_API twice: once with\n"
"       `features = 0` to detect features supported by this kernel, and\n"
"       again with the subset of features the program actually wants to\n"
"       enable. */\n"
"    uffdio_api.api = UFFD_API;\n"
"    uffdio_api.features = 0;\n"
"    if (ioctl(uffd, UFFDIO_API, &uffdio_api) == -1)\n"
"        err(EXIT_FAILURE, \"ioctl-UFFDIO_API\");\n"
"\\&\n"
"    /* Create a private anonymous mapping. The memory will be\n"
"       demand-zero paged--that is, not yet allocated. When we\n"
"       actually touch the memory, it will be allocated via\n"
"       the userfaultfd. */\n"
"\\&\n"
"    addr = mmap(NULL, len, PROT_READ | PROT_WRITE,\n"
"                MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);\n"
"    if (addr == MAP_FAILED)\n"
"        err(EXIT_FAILURE, \"mmap\");\n"
"\\&\n"
"    printf(\"Address returned by mmap() = %p\\en\", addr);\n"
"\\&\n"
"    /* Register the memory range of the mapping we just created for\n"
"       handling by the userfaultfd object. In mode, we request to track\n"
"       missing pages (i.e., pages that have not yet been faulted in). */\n"
"\\&\n"
"    uffdio_register.range.start = (unsigned long) addr;\n"
"    uffdio_register.range.len = len;\n"
"    uffdio_register.mode = UFFDIO_REGISTER_MODE_MISSING;\n"
"    if (ioctl(uffd, UFFDIO_REGISTER, &uffdio_register) == -1)\n"
"        err(EXIT_FAILURE, \"ioctl-UFFDIO_REGISTER\");\n"
"\\&\n"
"    /* Create a thread that will process the userfaultfd events. */\n"
"\\&\n"
"    s = pthread_create(&thr, NULL, fault_handler_thread, (void *) uffd);\n"
"    if (s != 0) {\n"
"        errc(EXIT_FAILURE, s, \"pthread_create\");\n"
"    }\n"
"\\&\n"
"    /* Main thread now touches memory in the mapping, touching\n"
"       locations 1024 bytes apart. This will trigger userfaultfd\n"
"       events for all pages in the region. */\n"
"\\&\n"
"    l = 0xf;    /* Ensure that faulting address is not on a page\n"
"                   boundary, in order to test that we correctly\n"
"                   handle that case in fault_handling_thread(). */\n"
"    while (l E<lt> len) {\n"
"        c = addr[l];\n"
"        printf(\"Read address %p in %s(): \", addr + l, __func__);\n"
"        printf(\"%c\\en\", c);\n"
"        l += 1024;\n"
"        usleep(100000);         /* Slow things down a little */\n"
"    }\n"
"\\&\n"
"    exit(EXIT_SUCCESS);\n"
"}\n"
msgstr ""

#.  SRC END
#. type: SH
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
#, no-wrap
msgid "SEE ALSO"
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid ""
"B<fcntl>(2), B<ioctl>(2), B<ioctl_userfaultfd>(2), B<madvise>(2), B<mmap>(2)"
msgstr ""

#. type: Plain text
#: archlinux debian-bookworm debian-unstable fedora-40 fedora-rawhide
#: mageia-cauldron opensuse-leap-15-6 opensuse-tumbleweed
msgid ""
"I<Documentation/admin-guide/mm/userfaultfd.rst> in the Linux kernel source "
"tree"
msgstr ""

#. type: TH
#: debian-bookworm
#, no-wrap
msgid "2023-02-05"
msgstr ""

#. type: TH
#: debian-bookworm
#, no-wrap
msgid "Linux man-pages 6.03"
msgstr ""

#. type: Plain text
#: debian-bookworm opensuse-leap-15-6
msgid ""
"After the userfaultfd object is created with B<userfaultfd>(), the "
"application must enable it using the B<UFFDIO_API> B<ioctl>(2)  operation.  "
"This operation allows a handshake between the kernel and user space to "
"determine the API version and supported features.  This operation must be "
"performed before any of the other B<ioctl>(2)  operations described below "
"(or those operations fail with the B<EINVAL> error)."
msgstr ""

#. type: Plain text
#: debian-bookworm opensuse-leap-15-6
msgid ""
"After a successful B<UFFDIO_API> operation, the application then registers "
"memory address ranges using the B<UFFDIO_REGISTER> B<ioctl>(2)  operation.  "
"After successful completion of a B<UFFDIO_REGISTER> operation, a page fault "
"occurring in the requested memory range, and satisfying the mode defined at "
"the registration time, will be forwarded by the kernel to the user-space "
"application.  The application can then use the B<UFFDIO_COPY ,> "
"B<UFFDIO_ZEROPAGE ,> or B<UFFDIO_CONTINUE> B<ioctl>(2)  operations to "
"resolve the page fault."
msgstr ""

#. type: Plain text
#: debian-bookworm opensuse-leap-15-6
#, no-wrap
msgid ""
"struct uffd_msg {\n"
"    __u8  event;            /* Type of event */\n"
"    ...\n"
"    union {\n"
"        struct {\n"
"            __u64 flags;    /* Flags describing fault */\n"
"            __u64 address;  /* Faulting address */\n"
"            union {\n"
"                __u32 ptid; /* Thread ID of the fault */\n"
"            } feat;\n"
"        } pagefault;\n"
msgstr ""

#. type: Plain text
#: debian-bookworm opensuse-leap-15-6
#, no-wrap
msgid ""
"        struct {            /* Since Linux 4.11 */\n"
"            __u32 ufd;      /* Userfault file descriptor\n"
"                               of the child process */\n"
"        } fork;\n"
msgstr ""

#. type: Plain text
#: debian-bookworm opensuse-leap-15-6
#, no-wrap
msgid ""
"        struct {            /* Since Linux 4.11 */\n"
"            __u64 from;     /* Old address of remapped area */\n"
"            __u64 to;       /* New address of remapped area */\n"
"            __u64 len;      /* Original mapping length */\n"
"        } remap;\n"
msgstr ""

#. type: Plain text
#: debian-bookworm opensuse-leap-15-6
#, no-wrap
msgid ""
"        struct {            /* Since Linux 4.11 */\n"
"            __u64 start;    /* Start address of removed area */\n"
"            __u64 end;      /* End address of removed area */\n"
"        } remove;\n"
"        ...\n"
"    } arg;\n"
msgstr ""

#. type: Plain text
#: debian-bookworm opensuse-leap-15-6
#, no-wrap
msgid ""
"    /* Padding fields omitted */\n"
"} __packed;\n"
msgstr ""

#. type: SH
#: debian-bookworm
#, no-wrap
msgid "VERSIONS"
msgstr ""

#. type: Plain text
#: debian-bookworm
msgid "The B<userfaultfd>()  system call first appeared in Linux 4.3."
msgstr ""

#. type: Plain text
#: debian-bookworm
msgid ""
"The support for hugetlbfs and shared memory areas and non-page-fault events "
"was added in Linux 4.11"
msgstr ""

#. type: Plain text
#: debian-bookworm
msgid ""
"B<userfaultfd>()  is Linux-specific and should not be used in programs "
"intended to be portable."
msgstr ""

#. type: Plain text
#: debian-bookworm opensuse-leap-15-6
#, no-wrap
msgid ""
"$ B<./userfaultfd_demo 3>\n"
"Address returned by mmap() = 0x7fd30106c000\n"
msgstr ""

#. type: Plain text
#: debian-bookworm opensuse-leap-15-6
#, no-wrap
msgid ""
"fault_handler_thread():\n"
"    poll() returns: nready = 1; POLLIN = 1; POLLERR = 0\n"
"    UFFD_EVENT_PAGEFAULT event: flags = 0; address = 7fd30106c00f\n"
"        (uffdio_copy.copy returned 4096)\n"
"Read address 0x7fd30106c00f in main(): A\n"
"Read address 0x7fd30106c40f in main(): A\n"
"Read address 0x7fd30106c80f in main(): A\n"
"Read address 0x7fd30106cc0f in main(): A\n"
msgstr ""

#. type: Plain text
#: debian-bookworm opensuse-leap-15-6
#, no-wrap
msgid ""
"fault_handler_thread():\n"
"    poll() returns: nready = 1; POLLIN = 1; POLLERR = 0\n"
"    UFFD_EVENT_PAGEFAULT event: flags = 0; address = 7fd30106d00f\n"
"        (uffdio_copy.copy returned 4096)\n"
"Read address 0x7fd30106d00f in main(): B\n"
"Read address 0x7fd30106d40f in main(): B\n"
"Read address 0x7fd30106d80f in main(): B\n"
"Read address 0x7fd30106dc0f in main(): B\n"
msgstr ""

#. type: Plain text
#: debian-bookworm opensuse-leap-15-6
#, no-wrap
msgid ""
"fault_handler_thread():\n"
"    poll() returns: nready = 1; POLLIN = 1; POLLERR = 0\n"
"    UFFD_EVENT_PAGEFAULT event: flags = 0; address = 7fd30106e00f\n"
"        (uffdio_copy.copy returned 4096)\n"
"Read address 0x7fd30106e00f in main(): C\n"
"Read address 0x7fd30106e40f in main(): C\n"
"Read address 0x7fd30106e80f in main(): C\n"
"Read address 0x7fd30106ec0f in main(): C\n"
msgstr ""

#. type: Plain text
#: debian-bookworm opensuse-leap-15-6
#, no-wrap
msgid "/* userfaultfd_demo.c\n"
msgstr ""

#. type: Plain text
#: debian-bookworm opensuse-leap-15-6
#, no-wrap
msgid ""
"   Licensed under the GNU General Public License version 2 or later.\n"
"*/\n"
"#define _GNU_SOURCE\n"
"#include E<lt>err.hE<gt>\n"
"#include E<lt>errno.hE<gt>\n"
"#include E<lt>fcntl.hE<gt>\n"
"#include E<lt>inttypes.hE<gt>\n"
"#include E<lt>linux/userfaultfd.hE<gt>\n"
"#include E<lt>poll.hE<gt>\n"
"#include E<lt>pthread.hE<gt>\n"
"#include E<lt>stdio.hE<gt>\n"
"#include E<lt>stdlib.hE<gt>\n"
"#include E<lt>string.hE<gt>\n"
"#include E<lt>sys/ioctl.hE<gt>\n"
"#include E<lt>sys/mman.hE<gt>\n"
"#include E<lt>sys/syscall.hE<gt>\n"
"#include E<lt>unistd.hE<gt>\n"
msgstr ""

#. type: Plain text
#: debian-bookworm opensuse-leap-15-6
#, no-wrap
msgid "static int page_size;\n"
msgstr ""

#. type: Plain text
#: debian-bookworm opensuse-leap-15-6
#, no-wrap
msgid ""
"static void *\n"
"fault_handler_thread(void *arg)\n"
"{\n"
"    int                 nready;\n"
"    long                uffd;   /* userfaultfd file descriptor */\n"
"    ssize_t             nread;\n"
"    struct pollfd       pollfd;\n"
"    struct uffdio_copy  uffdio_copy;\n"
msgstr ""

#. type: Plain text
#: debian-bookworm opensuse-leap-15-6
#, no-wrap
msgid ""
"    static int      fault_cnt = 0; /* Number of faults so far handled */\n"
"    static char     *page = NULL;\n"
"    static struct uffd_msg  msg;  /* Data read from userfaultfd */\n"
msgstr ""

#. type: Plain text
#: debian-bookworm opensuse-leap-15-6
#, no-wrap
msgid "    uffd = (long) arg;\n"
msgstr ""

#. type: Plain text
#: debian-bookworm opensuse-leap-15-6
#, no-wrap
msgid "    /* Create a page that will be copied into the faulting region. */\n"
msgstr ""

#. type: Plain text
#: debian-bookworm opensuse-leap-15-6
#, no-wrap
msgid ""
"    if (page == NULL) {\n"
"        page = mmap(NULL, page_size, PROT_READ | PROT_WRITE,\n"
"                    MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);\n"
"        if (page == MAP_FAILED)\n"
"            err(EXIT_FAILURE, \"mmap\");\n"
"    }\n"
msgstr ""

#. type: Plain text
#: debian-bookworm opensuse-leap-15-6
#, no-wrap
msgid ""
"    /* Loop, handling incoming events on the userfaultfd\n"
"       file descriptor. */\n"
msgstr ""

#. type: Plain text
#: debian-bookworm opensuse-leap-15-6
#, no-wrap
msgid "    for (;;) {\n"
msgstr ""

#. type: Plain text
#: debian-bookworm opensuse-leap-15-6
#, no-wrap
msgid "        /* See what poll() tells us about the userfaultfd. */\n"
msgstr ""

#. type: Plain text
#: debian-bookworm opensuse-leap-15-6
#, no-wrap
msgid ""
"        pollfd.fd = uffd;\n"
"        pollfd.events = POLLIN;\n"
"        nready = poll(&pollfd, 1, -1);\n"
"        if (nready == -1)\n"
"            err(EXIT_FAILURE, \"poll\");\n"
msgstr ""

#. type: Plain text
#: debian-bookworm opensuse-leap-15-6
#, no-wrap
msgid ""
"        printf(\"\\enfault_handler_thread():\\en\");\n"
"        printf(\"    poll() returns: nready = %d; \"\n"
"               \"POLLIN = %d; POLLERR = %d\\en\", nready,\n"
"               (pollfd.revents & POLLIN) != 0,\n"
"               (pollfd.revents & POLLERR) != 0);\n"
msgstr ""

#. type: Plain text
#: debian-bookworm opensuse-leap-15-6
#, no-wrap
msgid "        /* Read an event from the userfaultfd. */\n"
msgstr ""

#. type: Plain text
#: debian-bookworm opensuse-leap-15-6
#, no-wrap
msgid ""
"        nread = read(uffd, &msg, sizeof(msg));\n"
"        if (nread == 0) {\n"
"            printf(\"EOF on userfaultfd!\\en\");\n"
"            exit(EXIT_FAILURE);\n"
"        }\n"
msgstr ""

#. type: Plain text
#: debian-bookworm opensuse-leap-15-6
#, no-wrap
msgid ""
"        if (nread == -1)\n"
"            err(EXIT_FAILURE, \"read\");\n"
msgstr ""

#. type: Plain text
#: debian-bookworm opensuse-leap-15-6
#, no-wrap
msgid "        /* We expect only one kind of event; verify that assumption. */\n"
msgstr ""

#. type: Plain text
#: debian-bookworm opensuse-leap-15-6
#, no-wrap
msgid ""
"        if (msg.event != UFFD_EVENT_PAGEFAULT) {\n"
"            fprintf(stderr, \"Unexpected event on userfaultfd\\en\");\n"
"            exit(EXIT_FAILURE);\n"
"        }\n"
msgstr ""

#. type: Plain text
#: debian-bookworm opensuse-leap-15-6
#, no-wrap
msgid "        /* Display info about the page-fault event. */\n"
msgstr ""

#. type: Plain text
#: debian-bookworm opensuse-leap-15-6
#, no-wrap
msgid ""
"        printf(\"    UFFD_EVENT_PAGEFAULT event: \");\n"
"        printf(\"flags = %\"PRIx64\"; \", msg.arg.pagefault.flags);\n"
"        printf(\"address = %\"PRIx64\"\\en\", msg.arg.pagefault.address);\n"
msgstr ""

#. type: Plain text
#: debian-bookworm opensuse-leap-15-6
#, no-wrap
msgid ""
"        /* Copy the page pointed to by \\[aq]page\\[aq] into the faulting\n"
"           region. Vary the contents that are copied in, so that it\n"
"           is more obvious that each fault is handled separately. */\n"
msgstr ""

#. type: Plain text
#: debian-bookworm opensuse-leap-15-6
#, no-wrap
msgid ""
"        memset(page, \\[aq]A\\[aq] + fault_cnt % 20, page_size);\n"
"        fault_cnt++;\n"
msgstr ""

#. type: Plain text
#: debian-bookworm opensuse-leap-15-6
#, no-wrap
msgid "        uffdio_copy.src = (unsigned long) page;\n"
msgstr ""

#. type: Plain text
#: debian-bookworm opensuse-leap-15-6
#, no-wrap
msgid ""
"        /* We need to handle page faults in units of pages(!).\n"
"           So, round faulting address down to page boundary. */\n"
msgstr ""

#. type: Plain text
#: debian-bookworm opensuse-leap-15-6
#, no-wrap
msgid ""
"        uffdio_copy.dst = (unsigned long) msg.arg.pagefault.address &\n"
"                                           \\[ti](page_size - 1);\n"
"        uffdio_copy.len = page_size;\n"
"        uffdio_copy.mode = 0;\n"
"        uffdio_copy.copy = 0;\n"
"        if (ioctl(uffd, UFFDIO_COPY, &uffdio_copy) == -1)\n"
"            err(EXIT_FAILURE, \"ioctl-UFFDIO_COPY\");\n"
msgstr ""

#. type: Plain text
#: debian-bookworm opensuse-leap-15-6
#, no-wrap
msgid ""
"        printf(\"        (uffdio_copy.copy returned %\"PRId64\")\\en\",\n"
"               uffdio_copy.copy);\n"
"    }\n"
"}\n"
msgstr ""

#. type: Plain text
#: debian-bookworm opensuse-leap-15-6
#, no-wrap
msgid ""
"int\n"
"main(int argc, char *argv[])\n"
"{\n"
"    int        s;\n"
"    char       c;\n"
"    char       *addr;   /* Start of region handled by userfaultfd */\n"
"    long       uffd;    /* userfaultfd file descriptor */\n"
"    size_t     len, l;  /* Length of region handled by userfaultfd */\n"
"    pthread_t  thr;     /* ID of thread that handles page faults */\n"
"    struct uffdio_api       uffdio_api;\n"
"    struct uffdio_register  uffdio_register;\n"
msgstr ""

#. type: Plain text
#: debian-bookworm opensuse-leap-15-6
#, no-wrap
msgid ""
"    if (argc != 2) {\n"
"        fprintf(stderr, \"Usage: %s num-pages\\en\", argv[0]);\n"
"        exit(EXIT_FAILURE);\n"
"    }\n"
msgstr ""

#. type: Plain text
#: debian-bookworm opensuse-leap-15-6
#, no-wrap
msgid ""
"    page_size = sysconf(_SC_PAGE_SIZE);\n"
"    len = strtoull(argv[1], NULL, 0) * page_size;\n"
msgstr ""

#. type: Plain text
#: debian-bookworm opensuse-leap-15-6
#, no-wrap
msgid "    /* Create and enable userfaultfd object. */\n"
msgstr ""

#. type: Plain text
#: debian-bookworm opensuse-leap-15-6
#, no-wrap
msgid ""
"    uffd = syscall(SYS_userfaultfd, O_CLOEXEC | O_NONBLOCK);\n"
"    if (uffd == -1)\n"
"        err(EXIT_FAILURE, \"userfaultfd\");\n"
msgstr ""

#. type: Plain text
#: debian-bookworm opensuse-leap-15-6
#, no-wrap
msgid ""
"    uffdio_api.api = UFFD_API;\n"
"    uffdio_api.features = 0;\n"
"    if (ioctl(uffd, UFFDIO_API, &uffdio_api) == -1)\n"
"        err(EXIT_FAILURE, \"ioctl-UFFDIO_API\");\n"
msgstr ""

#. type: Plain text
#: debian-bookworm opensuse-leap-15-6
#, no-wrap
msgid ""
"    /* Create a private anonymous mapping. The memory will be\n"
"       demand-zero paged--that is, not yet allocated. When we\n"
"       actually touch the memory, it will be allocated via\n"
"       the userfaultfd. */\n"
msgstr ""

#. type: Plain text
#: debian-bookworm opensuse-leap-15-6
#, no-wrap
msgid ""
"    addr = mmap(NULL, len, PROT_READ | PROT_WRITE,\n"
"                MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);\n"
"    if (addr == MAP_FAILED)\n"
"        err(EXIT_FAILURE, \"mmap\");\n"
msgstr ""

#. type: Plain text
#: debian-bookworm opensuse-leap-15-6
#, no-wrap
msgid "    printf(\"Address returned by mmap() = %p\\en\", addr);\n"
msgstr ""

#. type: Plain text
#: debian-bookworm opensuse-leap-15-6
#, no-wrap
msgid ""
"    /* Register the memory range of the mapping we just created for\n"
"       handling by the userfaultfd object. In mode, we request to track\n"
"       missing pages (i.e., pages that have not yet been faulted in). */\n"
msgstr ""

#. type: Plain text
#: debian-bookworm opensuse-leap-15-6
#, no-wrap
msgid ""
"    uffdio_register.range.start = (unsigned long) addr;\n"
"    uffdio_register.range.len = len;\n"
"    uffdio_register.mode = UFFDIO_REGISTER_MODE_MISSING;\n"
"    if (ioctl(uffd, UFFDIO_REGISTER, &uffdio_register) == -1)\n"
"        err(EXIT_FAILURE, \"ioctl-UFFDIO_REGISTER\");\n"
msgstr ""

#. type: Plain text
#: debian-bookworm opensuse-leap-15-6
#, no-wrap
msgid "    /* Create a thread that will process the userfaultfd events. */\n"
msgstr ""

#. type: Plain text
#: debian-bookworm opensuse-leap-15-6
#, no-wrap
msgid ""
"    s = pthread_create(&thr, NULL, fault_handler_thread, (void *) uffd);\n"
"    if (s != 0) {\n"
"        errc(EXIT_FAILURE, s, \"pthread_create\");\n"
"    }\n"
msgstr ""

#. type: Plain text
#: debian-bookworm opensuse-leap-15-6
#, no-wrap
msgid ""
"    /* Main thread now touches memory in the mapping, touching\n"
"       locations 1024 bytes apart. This will trigger userfaultfd\n"
"       events for all pages in the region. */\n"
msgstr ""

#. type: Plain text
#: debian-bookworm opensuse-leap-15-6
#, no-wrap
msgid ""
"    l = 0xf;    /* Ensure that faulting address is not on a page\n"
"                   boundary, in order to test that we correctly\n"
"                   handle that case in fault_handling_thread(). */\n"
"    while (l E<lt> len) {\n"
"        c = addr[l];\n"
"        printf(\"Read address %p in %s(): \", addr + l, __func__);\n"
"        printf(\"%c\\en\", c);\n"
"        l += 1024;\n"
"        usleep(100000);         /* Slow things down a little */\n"
"    }\n"
msgstr ""

#. type: Plain text
#: debian-bookworm opensuse-leap-15-6
#, no-wrap
msgid ""
"    exit(EXIT_SUCCESS);\n"
"}\n"
msgstr ""

#. type: TH
#: fedora-40 fedora-rawhide mageia-cauldron
#, no-wrap
msgid "2024-02-12"
msgstr ""

#. type: TH
#: fedora-40 mageia-cauldron
#, no-wrap
msgid "Linux man-pages 6.06"
msgstr ""

#. type: TH
#: fedora-rawhide
#, no-wrap
msgid "Linux man-pages 6.7"
msgstr ""

#. type: TH
#: opensuse-leap-15-6
#, no-wrap
msgid "2023-03-30"
msgstr ""

#. type: TH
#: opensuse-leap-15-6
#, no-wrap
msgid "Linux man-pages 6.04"
msgstr ""

#. type: TH
#: opensuse-tumbleweed
#, no-wrap
msgid "Linux man-pages (unreleased)"
msgstr ""