Re: [PATCH v24 5/9] arm64: kdump: add kdump support

[AKASHI Takahiro <takahiro.akashi@linaro.org>]

On Fri, Aug 19, 2016 at 04:52:17PM +0530, Pratyush Anand wrote:
> On 19/08/2016:10:26:52 AM, AKASHI Takahiro wrote:
> > >From 740563e4a437f0d6ecf6e421c91433f9b8f19041 Mon Sep 17 00:00:00 2001
> > From: AKASHI Takahiro <takahiro.akashi@linaro.org>
> > Date: Fri, 19 Aug 2016 09:57:52 +0900
> > Subject: [PATCH] arm64: mark reserved memblock regions explicitly
> > 
> > ---
> >  arch/arm64/kernel/setup.c | 9 +++++++--
> >  1 file changed, 7 insertions(+), 2 deletions(-)
> > 
> > diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
> > index 38eda13..38589b5 100644
> > --- a/arch/arm64/kernel/setup.c
> > +++ b/arch/arm64/kernel/setup.c
> > @@ -205,10 +205,15 @@ static void __init request_standard_resources(void)
> >  
> >  	for_each_memblock(memory, region) {
> >  		res = alloc_bootmem_low(sizeof(*res));
> > -		res->name  = "System RAM";
> > +		if (memblock_is_nomap(region)) {
> > +			res->name  = "reserved";
> > +			res->flags = IORESOURCE_MEM | IORESOURCE_BUSY;
> > +		} else {
> > +			res->name  = "System RAM";
> > +			res->flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY;
> > +		}
> >  		res->start = __pfn_to_phys(memblock_region_memory_base_pfn(region));
> >  		res->end = __pfn_to_phys(memblock_region_memory_end_pfn(region)) - 1;
> > -		res->flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY;
> >  
> >  		request_resource(&iomem_resource, res);
> 
> 
> It will help kexec-tools to prevent copying  of any unnecessary data. I
> think, then you also need to change phys_offset calculation in kexec-tools. That
> should be start of either of first "reserved" or "System RAM" block.

Good point, but I'm not sure this is always true.
Is there any system whose ACPI memory is *not* part of DRAM
(so not part of linear mapping)?

Thanks,
-Takahiro AKASHI

> ~Pratyush

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