Re: [PATCH v11 5/5] kdump: update Documentation about crashkernel

Dave Young
2020-08-19T12:03:40Z

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
> >
> >
> > .
> >