linux-kernel - Re: [PATCH] livepatch: Make livepatch dependent on !TRIM_UNUSED

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Message-ID: <20170526215325.fa4qeyhstijgmb7e@jeyu>
Date:   Fri, 26 May 2017 14:53:25 -0700
From:   Jessica Yu <jeyu@...hat.com>
To:     Miroslav Benes <mbenes@...e.cz>
Cc:     jpoimboe@...hat.com, jikos@...nel.org, mmarek@...e.com,
        pmladek@...e.com, jmoreira@...e.de, live-patching@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] livepatch: Make livepatch dependent on !TRIM_UNUSED_KSYMS

+++ Miroslav Benes [26/05/17 14:45 +0200]:
>If TRIM_UNUSED_KSYMS is enabled, all unneeded exported symbols are made
>unexported. Two-pass build of the kernel is done to find out which
>symbols are needed based on a configuration. This effectively
>complicates things for out-of-tree modules.
>
>Livepatch exports functions to (un)register and enable/disable a live
>patch. The only in-tree module which uses these functions is a sample in
>samples/livepatch/. If the sample is disabled, the functions are
>trimmed and out-of-tree live patches cannot be built.
>
>Note that live patches are intended to be built out-of-tree.
>
>Suggested-by: Michal Marek <mmarek@...e.com>
>Signed-off-by: Miroslav Benes <mbenes@...e.cz>

Makes sense to me:

Acked-by: Jessica Yu <jeyu@...hat.com>

>---
> kernel/livepatch/Kconfig | 1 +
> 1 file changed, 1 insertion(+)
>
>diff --git a/kernel/livepatch/Kconfig b/kernel/livepatch/Kconfig
>index 045022557936..ec4565122e65 100644
>--- a/kernel/livepatch/Kconfig
>+++ b/kernel/livepatch/Kconfig
>@@ -10,6 +10,7 @@ config LIVEPATCH
> 	depends on SYSFS
> 	depends on KALLSYMS_ALL
> 	depends on HAVE_LIVEPATCH
>+	depends on !TRIM_UNUSED_KSYMS
> 	help
> 	  Say Y here if you want to support kernel live patching.
> 	  This option has no runtime impact until a kernel "patch"
>-- 
>2.12.2
>