linux-kernel - Re: [PATCH v14 03/11] x86: kdump: use macro CRASH_ADDR_LOW_MAX in functions reserve

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Message-ID: <20210218082241.GJ2871@MiWiFi-R3L-srv>
Date:   Thu, 18 Feb 2021 16:23:23 +0800
From:   Baoquan He <bhe@...hat.com>
To:     Chen Zhou <chenzhou10@...wei.com>
Cc:     mingo@...hat.com, tglx@...utronix.de, rppt@...nel.org,
        dyoung@...hat.com, catalin.marinas@....com, will@...nel.org,
        nsaenzjulienne@...e.de, corbet@....net, John.P.donnelly@...cle.com,
        prabhakar.pkin@...il.com, horms@...ge.net.au, robh+dt@...nel.org,
        arnd@...db.de, james.morse@....com, xiexiuqi@...wei.com,
        guohanjun@...wei.com, huawei.libin@...wei.com,
        wangkefeng.wang@...wei.com, linux-doc@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        kexec@...ts.infradead.org
Subject: Re: [PATCH v14 03/11] x86: kdump: use macro CRASH_ADDR_LOW_MAX in
 functions reserve_crashkernel()

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 <chenzhou10@...wei.com>
> Tested-by: John Donnelly <John.p.donnelly@...cle.com>
> ---
>  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 <bhe@...hat.com>

>  	}
> -- 
> 2.20.1
>