Re: [PATCH v17 03/10] x86: kdump: use macro CRASH_ADDR_LOW_MAX in functions reserve_crashkernel()

[john . p . donnelly]

On 12/10/21 12:55 AM, Zhen Lei wrote:
> From: Chen Zhou <chenzhou10@xxxxxxxxxx>
>
> To make the functions reserve_crashkernel() as generic,
> replace some hard-coded numbers with macro CRASH_ADDR_LOW_MAX.
>
> Signed-off-by: Chen Zhou <chenzhou10@xxxxxxxxxx>
> Signed-off-by: Zhen Lei <thunder.leizhen@xxxxxxxxxx>
> Tested-by: John Donnelly <John.p.donnelly@xxxxxxxxxx>
> Tested-by: Dave Kleikamp <dave.kleikamp@xxxxxxxxxx>
> Acked-by: Baoquan He <bhe@xxxxxxxxxx>

 Acked-by: John Donnelly <john.p.donnelly@xxxxxxxxxx>

> ---
>   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 6424ee4f23da2cf..bb2a0973b98059e 100644
> --- a/arch/x86/kernel/setup.c
> +++ b/arch/x86/kernel/setup.c
> @@ -489,8 +489,9 @@ 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.
> @@ -518,7 +519,7 @@ 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_phys_free(crash_base, crash_size);
>   		return;
>   	}