linux-kernel - [PATCH] arm: make kexec depend on MMU

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Message-Id: <5b595d37283f043df78259221f2b7d18e0cb0ce5.1580942558.git.stefan@agner.ch>
Date:   Wed,  5 Feb 2020 23:43:44 +0100
From:   Stefan Agner <stefan@...er.ch>
To:     linux@...linux.org.uk
Cc:     arnd@...db.de, linus.walleij@...aro.org, akpm@...ux-foundation.org,
        nsekhar@...com, mchehab+samsung@...nel.org,
        bgolaszewski@...libre.com, armlinux@...isordat.com,
        benjamin.gaignard@...aro.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, Michal Hocko <mhocko@...e.com>,
        Stefan Agner <stefan@...er.ch>
Subject: [PATCH] arm: make kexec depend on MMU

From: Michal Hocko <mhocko@...e.com>

arm nommu config with KEXEC enabled doesn't compile
arch/arm/kernel/setup.c: In function 'reserve_crashkernel':
arch/arm/kernel/setup.c:1005:25: error: 'SECTION_SIZE' undeclared (first
use in this function)
             crash_size, SECTION_SIZE);

since 61603016e212 ("ARM: kexec: fix crashkernel= handling") which is
over one year without anybody noticing. I have only noticed beause of
my testing nommu config which somehow gained CONFIG_KEXEC without
an intention. This suggests that nobody is actually using KEXEC
on nommu ARM configs. It is even a question whether kexec works with
nommu.

Make KEXEC depend on MMU to make this clear. If somebody wants to enable
there will be probably more things to take care.

Signed-off-by: Michal Hocko <mhocko@...e.com>
Reviewed-by: Stefan Agner <stefan@...er.ch>
Signed-off-by: Stefan Agner <stefan@...er.ch>
---
 arch/arm/Kconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 96dab76da3b3..59ce8943151f 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -1906,6 +1906,7 @@ config KEXEC
 	bool "Kexec system call (EXPERIMENTAL)"
 	depends on (!SMP || PM_SLEEP_SMP)
 	depends on !CPU_V7M
+	depends on MMU
 	select KEXEC_CORE
 	help
 	  kexec is a system call that implements the ability to shutdown your
-- 
2.25.0