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Date:   Wed, 19 Aug 2020 20:03:01 +0800
From:   Dave Young <dyoung@redhat.com>
To:     chenzhou <chenzhou10@huawei.com>
Cc:     catalin.marinas@arm.com, will@kernel.org, james.morse@arm.com,
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        guohanjun@huawei.com, xiexiuqi@huawei.com, huawei.libin@huawei.com,
        wangkefeng.wang@huawei.com
Subject: Re: [PATCH v11 5/5] kdump: update Documentation about crashkernel
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On 08/18/20 at 03:07pm, chenzhou wrote:
> 
> 
> On 2020/8/10 14:03, Dave Young wrote:
> > Hi,
> >
> >>> Previously I remember we talked about to use similar logic as X86, but I
> >>> remember you mentioned on some arm64 platform there could be no low
> >>> memory at all.  Is this not a problem now for the fallback?  Just be
> >>> curious, thanks for the update, for the common part looks good.
> >> Hi Dave,
> >>
> >> Did you mean this discuss: https://lkml.org/lkml/2019/12/27/122?
> > I meant about this reply instead :)
> > https://lkml.org/lkml/2020/1/16/616
> Hi Dave,
> 
> Sorry for not repley in time, I was on holiday last week.

Hi, no problem, thanks for following up.

> 
> The platform James mentioned may exist for which have no devices and need no low memory.
> For our arm64 server platform, there are some devices and need low memory.
> 
> I got it. For the platform with no low memory, reserving crashkernel will  always fail.
> How about like this:

I think the question should leave to Catalin or James, I have no
suggestion about this:)

> 
> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
> index a8e34d97a894..4df18c7ea438 100644
> --- a/arch/arm64/mm/init.c
> +++ b/arch/arm64/mm/init.c
> @@ -147,7 +147,7 @@ static void __init reserve_crashkernel(void)
>         }
>         memblock_reserve(crash_base, crash_size);
>  
> -       if (crash_base >= CRASH_ADDR_LOW_MAX) {
> +       if (memstart_addr < CRASH_ADDR_LOW_MAX && crash_base >= CRASH_ADDR_LOW_MAX) {
>                 const char *rename = "Crash kernel (low)";
>  
>                 if (reserve_crashkernel_low()) {
> 
> 
> Thanks,
> Chen Zhou
> 
> >
> > Thanks
> > Dave
> >
> >
> > .
> >
> 
>