From: "H. Peter Anvin" <hpa@zytor.com>
To: Vivek Goyal <vgoyal@redhat.com>, WANG Chao <chaowang@redhat.com>
Cc: kexec@lists.infradead.org, horms@verge.net.au,
ebiederm@xmission.com, jdmason@kudzu.us, dyoung@redhat.com,
Thomas Renninger <trenn@suse.de>
Subject: Re: [PATCH v2 0/4] kexec-tools, x86: E820 memmap pass for kdump
Date: Mon, 24 Feb 2014 07:27:15 -0800 [thread overview]
Message-ID: <5458fa7d-ca13-4c2a-bd76-344ceb7679cb@email.android.com> (raw)
In-Reply-To: <20140224152205.GC4631@redhat.com>
I would like to see if there is any actual use for it before doing anything else. The Calgary code may just be off.
On February 24, 2014 7:22:05 AM PST, Vivek Goyal <vgoyal@redhat.com> wrote:
>On Mon, Feb 24, 2014 at 10:58:41PM +0800, WANG Chao wrote:
>[..]
>> > Approaches to avoid saved_max_pfn in calgary case:
>> > 1) If done correctly from the beginning, the TCE table size would
>have
>> > been exposed via /sys and kexec-tools could simply add:
>> > calgary="128k|512K...|8M" which is already caught by
>pci-calgary and
>> > saved_max_pfn is not needed/touched anymore.
>> > -> Disadvantage: needs a new sysfs entry
>> > 2) When finding max_pfn for calgary table size usage, we could
>try in
>> > kdump case to use the highest memory (RAM or RESERVED) showing
>up
>> > in e820 map.
>>
>> How could this replace saved_max_pfn? The highest memory in kdump
>can't
>> necessarily be the real ram size. In kdump, RAM range is just part of
>the real
>> ram, not mentioning we don't pass RESERVED range to kdump E820.
>
>I vaguely remember there was some discussion about passing first
>kerne's
>RAM as special reserved ranges. Say E820_RESERVED_KDUMP. And use that
>to figure out saved_max_pfn.
>
>I personally feel that just create a new command line parameter
>"saved_max_pfn" and pass it to second kernel and be done with it.
>Modify
>calgary code to first look for saved_max_pfn and if not present,
>calculate
>saved_max_pfn from e820.
>
>saved_max_pfn command line option is pretty ugly, not sure what are the
>better options here.
>
>Thanks
>Vivek
--
Sent from my mobile phone. Please pardon brevity and lack of formatting.
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next prev parent reply other threads:[~2014-02-24 15:27 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-02-20 9:28 [PATCH v2 0/4] kexec-tools, x86: E820 memmap pass for kdump WANG Chao
2014-02-20 9:28 ` [PATCH v2 1/4] cleanup: add dbgprint_mem_range function WANG Chao
2014-02-20 9:28 ` [PATCH v2 2/4] x86: Store memory ranges globally used for crash kernel to boot into WANG Chao
2014-02-20 9:28 ` [PATCH v2 3/4] x86: add --pass-memmap-cmdline option WANG Chao
2014-02-20 9:28 ` [PATCH v2 4/4] x86: Pass memory range via E820 for kdump WANG Chao
2014-02-27 20:53 ` Linn Crosetto
2014-02-28 8:32 ` WANG Chao
2014-02-24 10:38 ` [PATCH v2 0/4] kexec-tools, x86: E820 memmap pass " Thomas Renninger
2014-02-24 14:58 ` WANG Chao
2014-02-24 15:03 ` H. Peter Anvin
2014-02-24 15:11 ` Vivek Goyal
2014-02-24 15:24 ` Vivek Goyal
2014-02-24 15:28 ` H. Peter Anvin
2014-02-24 15:22 ` Vivek Goyal
2014-02-24 15:27 ` H. Peter Anvin [this message]
2014-02-24 15:34 ` Thomas Renninger
2014-02-24 15:45 ` Vivek Goyal
2014-02-24 15:50 ` H. Peter Anvin
2014-02-24 15:59 ` Vivek Goyal
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