README: describe the different components of kpatch

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Josh Poimboeuf 2014-02-18 21:32:24 -06:00
parent 586813814c
commit 2ecd73abdb
1 changed files with 26 additions and 3 deletions

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@ -9,7 +9,7 @@ scale-out, run on a single machine and are very downtime
sensitive or require a heavyweight approval process and
notification of workload users in the event of downtime.
kpatch is currently is early development. For now, it should _not_ be used
kpatch is currently in active development. For now, it should _not_ be used
in production environments until significantly more testing on various
patches and environments is conducted.
@ -77,6 +77,29 @@ Done! The kernel is now patched.
How it works
------------
kpatch works at a function granularity: old functions are replaced with new
ones. It has four main components:
- **kpatch-build**: a collection of tools which convert a source diff patch to
a hot patch module. They work by compiling the kernel both with and without
the source patch, comparing the binaries, and generating a hot patch module
which includes new binary versions of the functions to be replaced.
- **hot patch module**: a kernel module (.ko file) which includes the
replacement functions and metadata about the original functions.
- **kpatch core module**: a kernel module (.ko file) which provides an
interface for the hot patch modules to register new functions for
replacement. It uses the kernel ftrace subsystem to hook into the original
function's mcount call instruction, so that a call to the original function
is redirected to the replacement function.
- **kpatch utility:** a command-line tool which allows a user to manage a
collection of hot patch modules. One or more hot patch modules may be
configured to be loaded at boot time, so that a system can remain patched
even after a reboot into the same version of the kernel.
### kpatch build
The "kpatch build" command converts a source-level diff patch file to a hot
@ -150,8 +173,8 @@ by the "kpatch build" command.
Get involved
------------
If you have feedback or you want to contribute, feel free to join the mailing
list at https://www.redhat.com/mailman/listinfo/kpatch and say hello.
If you have questions, feedback, or you'd like to contribute, feel free to join
the mailing list at https://www.redhat.com/mailman/listinfo/kpatch and say hi.
License