Re: [PATCH 8/9] arm: Add RAMOOPS memory area

[Sascha Hauer <s.hauer@pengutronix.de>]

On Wed, Dec 02, 2015 at 02:48:50PM +0100, Markus Pargmann wrote:
> RAMOOPS is a driver that uses a reserved static memory region to store
> the data from the last panic or boot. This helps to debug crashes at the
> next boot while preserving the boot messages.
> 
> To guarantee a memory area that is not altered by barebox or the kernel,
> this area is located at the end of the RAM right after barebox and
> before the STACK. This ensures that changing barebox sizes do not
> interfere with RAMOOPS.
> 
> Signed-off-by: Markus Pargmann <mpa@pengutronix.de>
> ---
>  arch/arm/cpu/start.c               |  6 ++++++
>  arch/arm/include/asm/barebox-arm.h | 14 +++++++++++++-
>  2 files changed, 19 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/arm/cpu/start.c b/arch/arm/cpu/start.c
> index 4ad64b61e86a..d03d1edfaf18 100644
> --- a/arch/arm/cpu/start.c
> +++ b/arch/arm/cpu/start.c
> @@ -118,6 +118,12 @@ static inline unsigned long arm_mem_boarddata(unsigned long membase,
>  	return mem;
>  }
>  
> +unsigned long arm_mem_ramoops_get(void)
> +{
> +	return arm_mem_ramoops(0, arm_stack_top);
> +}
> +EXPORT_SYMBOL_GPL(arm_mem_ramoops_get);
> +
>  static int barebox_memory_areas_init(void)
>  {
>  	unsigned long start = arm_head_bottom;
> diff --git a/arch/arm/include/asm/barebox-arm.h b/arch/arm/include/asm/barebox-arm.h
> index da7717538b61..91f1747d2df4 100644
> --- a/arch/arm/include/asm/barebox-arm.h
> +++ b/arch/arm/include/asm/barebox-arm.h
> @@ -122,11 +122,23 @@ static inline unsigned long arm_mem_early_malloc_end(unsigned long membase,
>  	return arm_mem_ttb(membase, endmem);
>  }
>  
> +static inline unsigned long arm_mem_ramoops(unsigned long membase,
> +					    unsigned long endmem)
> +{
> +	endmem = arm_mem_ttb(membase, endmem);
> +#ifdef CONFIG_FS_PSTORE_RAMOOPS
> +	endmem -= CONFIG_FS_PSTORE_RAMOOPS_SIZE;
> +	endmem &= ~(SZ_4K - 1); /* Align to 4K */
> +#endif

if (IS_ENABLED(CONFIG_FS_PSTORE_RAMOOPS)) please

Sascha

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