Subject: Re: kexec, x86: Need a new e820 type support for kexec
To: Baoquan He <bhe@redhat.com>
References: <1437697592.3214.373.camel@hp.com>
 <20150806081231.GA16699@dhcp-128-28.nay.redhat.com>
 <1438910038.3109.116.camel@hp.com>
 <20150818085330.GB15480@dhcp-128-28.nay.redhat.com>
 <1439910078.24434.106.camel@hp.com>
 <20150819025316.GD19950@dhcp-128-28.nay.redhat.com>
Cc: linux-nvdimm@ml01.01.org, kexec@lists.infradead.org, hch@lst.de,
        linux-kernel@vger.kernel.org
From: Toshi Kani <toshi.kani@hp.com>
Message-ID: <55D415C1.2010406@hp.com>
Date: Tue, 18 Aug 2015 23:36:01 -0600
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On 8/18/2015 8:53 PM, Baoquan He wrote:
> 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.

3) is fine, and I do not think we need a note either.  It does not make 
sense to add an memmap cmdline for PMEM since PMEM ranges require ACPI 
NFIT table.

Thanks,
-Toshi

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