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livepatch: Remove not longer valid limitations from the documentation 

Semantic changes are possible since the commit d83a7cb375
("livepatch: change to a per-task consistency model").

Also data structures can be patched since the commit 439e7271dc
("livepatch: introduce shadow variable API").

It is a high time we removed these limitations from the documentation.

Signed-off-by: Petr Mladek <pmladek@suse.com>
Acked-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
hifive-unleashed-5.1
Petr Mladek 2018-05-23 09:47:42 +02:00 committed by Jiri Kosina
parent 41e3bef52e
commit a48c7709fe
1 changed files with 0 additions and 24 deletions
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Documentation/livepatch/livepatch.txt
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@ -429,30 +429,6 @@ See Documentation/ABI/testing/sysfs-kernel-livepatch for more details.
The current Livepatch implementation has several limitations:
+ The patch must not change the semantic of the patched functions.
The current implementation guarantees only that either the old
or the new function is called. The functions are patched one
by one. It means that the patch must _not_ change the semantic
of the function.
+ Data structures can not be patched.
There is no support to version data structures or anyhow migrate
one structure into another. Also the simple consistency model does
not allow to switch more functions atomically.
Once there is more complex consistency mode, it will be possible to
use some workarounds. For example, it will be possible to use a hole
for a new member because the data structure is aligned. Or it will
be possible to use an existing member for something else.
There are no plans to add more generic support for modified structures
at the moment.
+ Only functions that can be traced could be patched.
Livepatch is based on the dynamic ftrace. In particular, functions