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 for kexec@lists.infradead.org; Wed, 31 Mar 2021 15:47:39 +0000
Subject: Re: [PATCH v1 1/3] crashdump/x86: dump any kind of "System RAM"
References: <20210323100111.8365-1-david@redhat.com>
 <20210323100111.8365-2-david@redhat.com>
From: Dave Hansen <dave.hansen@intel.com>
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Date: Wed, 31 Mar 2021 08:47:28 -0700
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To: David Hildenbrand <david@redhat.com>, kexec@lists.infradead.org
Cc: Dan Williams <dan.j.williams@intel.com>, Dave Hansen <dave.hansen@linux.intel.com>, Baoquan He <bhe@redhat.com>, Simon Horman <horms@verge.net.au>

On 3/23/21 3:01 AM, David Hildenbrand wrote:
> Traditionally, we had "System RAM" only on the top level of in the
> kernel resource tree (-> /proc/iomem). Nowadays, we can also have
> "System RAM" on lower levels of the tree -- driver-managed device memory
> that is always detected and added via drivers. Current examples are
> memory added via dax/kmem -- ("System RAM (kmem)") and virtio-mem ("System
> RAM (virtio_mem)"). Note that in some kernel versions "System RAM
> (kmem)" was exposed as "System RAM", but similarly, on lower levels of
> the resource tree.
> 
> Let's add anything that contains "System RAM" to the elf core header, so
> it will be dumped for kexec_load(). Handling kexec_file_load() in the
> kernel is similarly getting fixed [1].

Although I don't do a lot of hacking in the crashdump code, this seems
sane to me.  As the perpetrator of the "System RAM (kmem)" trick:

Acked-by: Dave Hansen <dave.hansen@linux.intel.com>


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