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Subject: Re: [PATCH] arm: Fix Kexec compilation issue.
To:     Vincenzo Frascino <vincenzo.frascino@arm.com>,
        linux@armlinux.org.uk
Cc:     linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org
References: <20200110123125.51092-1-vincenzo.frascino@arm.com>
From:   Vladimir Murzin <vladimir.murzin@arm.com>
Message-ID: <27d511d6-90de-02f1-733b-e177462dffab@arm.com>
Date:   Tue, 14 Jan 2020 13:44:26 +0000
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On 1/10/20 12:31 PM, Vincenzo Frascino wrote:
> To perform the reserve_crashkernel() operation kexec uses SECTION_SIZE to
> find a memblock in a range.
> SECTION_SIZE is not defined for nommu systems. Trying to compile kexec in
> these conditions results in a build error:
> 
>   linux/arch/arm/kernel/setup.c: In function ‘reserve_crashkernel’:
>   linux/arch/arm/kernel/setup.c:1016:25: error: ‘SECTION_SIZE’ undeclared
>      (first use in this function); did you mean ‘SECTIONS_WIDTH’?
>              crash_size, SECTION_SIZE);
>                          ^~~~~~~~~~~~
>                          SECTIONS_WIDTH
>   linux/arch/arm/kernel/setup.c:1016:25: note: each undeclared identifier
>      is reported only once for each function it appears in
>   linux/scripts/Makefile.build:265: recipe for target 'arch/arm/kernel/setup.o'
>      failed
> 
> Make KEXEC depend on MMU to fix the compilation issue.
> 
> Cc: Russell King <linux@armlinux.org.uk>
> Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
> ---
>  arch/arm/Kconfig | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
> index ba75e3661a41..bc99582bdc85 100644
> --- a/arch/arm/Kconfig
> +++ b/arch/arm/Kconfig
> @@ -1904,7 +1904,7 @@ config XIP_DEFLATED_DATA
>  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
> 

Reviewed-by: Vladimir Murzin <vladimir.murzin@arm.com>

Cheers
Vladimir