84 lines
2.2 KiB
Groff
84 lines
2.2 KiB
Groff
.\" Libor Pechacek <lpechacek@suse.com>
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.\"
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.TH KLP 8 2017-12-13 "SLES 15" "SLE Live Patching"
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.SH NAME
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kgr \- compatibility wrapper for migration from kGraft / SLE 12
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.SH SYNOPSIS
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.ll +8
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.B kgr
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.RB [ " \-hv " ]
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.RI COMMAND
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.ll -8
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.SH DESCRIPTION
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.I kgr
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is a lightweight wrapper for the new klp tool. It is provided for smooth
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migration from SLE 12 and will be removed in future SLE releases.
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.SH COMMANDS
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.TP
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.B status
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See klp(1) for description.
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.TP
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.B check
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See klp(1) for description.
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.TP
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.B patches
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See klp(1) for description.
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.TP
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.B blocking
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See klp(1) for description. Unlike the SLE 12 implementation, this command
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displays execution threads. Processes display is known to be incomplete for
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multi-threaded applications.
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.TP
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.B blocking_threads
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Obsolete command.
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Same as
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.I kgr
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.IR blocking .
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.TP
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.B poke
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Obsolete command. Send STOP and CONT signals to processess that are blocking
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kGraft progress. See
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.SM
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.B CAVEATS
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for discussion about this method.
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.SH OPTIONS
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.TP
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.B \-h --help
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Display a help screen and quit.
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.TP
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.B \-v --verbose
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Verbose. Makes
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.I kgr
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print out process command line with
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.B blocking
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and
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.B blocking_threads
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commands.
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Another
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.B \-v
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will display also strack traces.
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.TP
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.B \--version
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Version. Display the version number.
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.SH EXIT STATUS
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With
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.B
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check
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command the exit status is 0 when system is ready for kernel live patching and
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1 when patching is in progress. For other commands the exit status is 0 upon
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successful command completion and 1 upon error.
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.SH CAVEATS
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By design, kGraft technology requires the processes to cross the user
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space/kernel boundary to present them with the patched kernel code. Processes
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that sleep in kernel code at the time the patch module is loaded will prevent
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patching process from finishing until they leave kernel space. These processes
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usually leave kernel after the event, for which they are waiting, happens or
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timeout elapses.
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.P
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Sending regular processes STOP signal followed by CONT signal achieves the
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goal of making them to cross the user space/kernel boundary immediately. However, this
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method may not be suitable for all processes running in the system and does not
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apply to kernel threads and processess in
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.B D
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process state. This method is also known to interfere with shell job control.
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