Re: kexec, x86: Need a new e820 type support for kexec

From: Baoquan He <bhe@redhat.com>
Cc: linux-nvdimm@ml01.01.org, dan.j.williams@intel.com,
	kexec@lists.infradead.org, hch@lst.de,
	linux-kernel@vger.kernel.org
Subject: Re: kexec, x86: Need a new e820 type support for kexec
Date: Wed, 19 Aug 2015 10:53:16 +0800	[thread overview]
Message-ID: <20150819025316.GD19950@dhcp-128-28.nay.redhat.com> (raw)
In-Reply-To: <1439910078.24434.106.camel@hp.com>

On 08/18/15 at 09:01am, Toshi Kani wrote:
> On Tue, 2015-08-18 at 16:53 +0800, Baoquan He wrote:
> > Rethink it again, maybe it's better to pass PMEM as PRAM to kdump
> > kernel if user really want to use memmap way by specifying
> > --pass-memmap-cmdline. Then I need add the PMEM and PRAM checking here
> > you pointed out. Will repost with them.
> 
> No, you should not report PMEM as PRAM.  They are different things.  The
> kdump kernel does not need to support memmap cmdline for PMEM, as the
> regular kernel does not -- memmap cmdline cannot emulate PMEM.

OK. Then it will be wrong if people intend to specify
--pass-memmap-cmdline. There might be 3 ways to fix this:

1) add PMEM support in kernel. memmap cmdline is not only used for
emulating, but for kexec/kdump using.

2) Delete --pass-memmap-cmdline option in kexec-tools since people
rarely use it.

3) Add a note in kexec-tools that option --pass-memmap-cmdline can't
work together with PMEM, people should not use it.

Thanks
Baoquan

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