Subject: Re: [PATCH v14 03/11] x86: kdump: use macro CRASH_ADDR_LOW_MAX in functions reserve_crashkernel()

From: Baoquan He <[email-masked]>
Date: Thu, 18 Feb 2021 16:23:23 +0800

On 01/30/21 at 03:10pm, Chen Zhou wrote:
> To make the functions reserve_crashkernel() as generic,
> replace some hard-coded numbers with macro CRASH_ADDR_LOW_MAX.
> 
> Signed-off-by: Chen Zhou <[email-masked]>
> Tested-by: John Donnelly <[email-masked]>
> ---
>  arch/x86/kernel/setup.c | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
> index 27470479e4a3..086a04235be4 100644
> --- a/arch/x86/kernel/setup.c
> +++ b/arch/x86/kernel/setup.c
> @@ -487,8 +487,9 @@ static void __init reserve_crashkernel(void)
>  	if (!crash_base) {
>  		/*
>  		 * Set CRASH_ADDR_LOW_MAX upper bound for crash memory,
> -		 * crashkernel=x,high reserves memory over 4G, also allocates
> -		 * 256M extra low memory for DMA buffers and swiotlb.
> +		 * crashkernel=x,high reserves memory over CRASH_ADDR_LOW_MAX,
> +		 * also allocates 256M extra low memory for DMA buffers
> +		 * and swiotlb.
>  		 * But the extra memory is not required for all machines.
>  		 * So try low memory first and fall back to high memory
>  		 * unless "crashkernel=size[KMG],high" is specified.
> @@ -516,7 +517,7 @@ static void __init reserve_crashkernel(void)
>  		}
>  	}
>  
> -	if (crash_base >= (1ULL << 32) && reserve_crashkernel_low()) {
> +	if (crash_base >= CRASH_ADDR_LOW_MAX && reserve_crashkernel_low()) {
>  		memblock_free(crash_base, crash_size);
>  		return;

Acked-by: Baoquan He <[email-masked]>

>  	}
> -- 
> 2.20.1

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