From: Vivek Goyal <vgoyal@redhat.com>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: kexec@lists.infradead.org, heiko.carstens@de.ibm.com,
linux-kernel@vger.kernel.org, lisa.mitchell@hp.com,
HATAYAMA Daisuke <d.hatayama@jp.fujitsu.com>,
kumagai-atsushi@mxc.nes.nec.co.jp, zhangyanfei@cn.fujitsu.com,
akpm@linux-foundation.org, cpw@sgi.com
Subject: Re: [PATCH v3 08/21] vmcore: copy non page-size aligned head and tail pages in 2nd kernel
Date: Tue, 19 Mar 2013 17:22:44 -0400 [thread overview]
Message-ID: <20130319212244.GE3872@redhat.com> (raw)
In-Reply-To: <878v5jqf5e.fsf@xmission.com>
On Tue, Mar 19, 2013 at 01:59:57PM -0700, Eric W. Biederman wrote:
> HATAYAMA Daisuke <d.hatayama@jp.fujitsu.com> writes:
>
> > Due to mmap() requirement, we need to copy pages not starting or
> > ending with page-size aligned address in 2nd kernel and to map them to
> > user-space.
> >
> > For example, see the map below:
> >
> > 00000000-00010000 : reserved
> > 00010000-0009f800 : System RAM
> > 0009f800-000a0000 : reserved
> >
> > where the System RAM ends with 0x9f800 that is not page-size
> > aligned. This map is divided into two parts:
> >
> > 00010000-0009f000
> > 0009f000-0009f800
> >
> > and the first one is kept in old memory and the 2nd one is copied into
> > buffer on 2nd kernel.
> >
> > This kind of non-page-size-aligned area can always occur since any
> > part of System RAM can be converted into reserved area at runtime.
> >
> > If not doing copying like this and if remapping non page-size aligned
> > pages on old memory directly, mmap() had to export memory which is not
> > dump target to user-space. In the above example this is reserved
> > 0x9f800-0xa0000.
>
> So I have a question. Would it not be easier to only support mmaping on
> the things that are easily mmapable? And in the oddball corner cases
> require reading the data instead.
Hi Eric,
Are you saying that some parts of the vmcore file will support mmap() and
others will not. If yes, how would a user know which parts of file are
mappable and which are not.
Thanks
Vivek
_______________________________________________
kexec mailing list
kexec@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/kexec
next prev parent reply other threads:[~2013-03-19 21:22 UTC|newest]
Thread overview: 76+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-03-16 4:00 [PATCH v3 00/21] kdump, vmcore: support mmap() on /proc/vmcore HATAYAMA Daisuke
2013-03-16 4:00 ` [PATCH v3 01/21] vmcore: reference e_phoff member explicitly to get position of program header table HATAYAMA Daisuke
2013-03-19 21:44 ` Eric W. Biederman
2013-03-21 2:50 ` HATAYAMA Daisuke
2013-03-21 6:11 ` Eric W. Biederman
2013-03-21 14:12 ` Vivek Goyal
2013-03-22 0:25 ` HATAYAMA Daisuke
2013-03-16 4:00 ` [PATCH v3 02/21] vmcore: clean up by removing unnecessary variable HATAYAMA Daisuke
2013-03-16 4:01 ` [PATCH v3 03/21] vmcore: rearrange program headers without assuming consequtive PT_NOTE entries HATAYAMA Daisuke
2013-03-19 21:59 ` Eric W. Biederman
2013-03-16 4:01 ` [PATCH v3 04/21] vmcore, sysfs: export ELF note segment size instead of vmcoreinfo data size HATAYAMA Daisuke
2013-03-16 4:01 ` [PATCH v3 05/21] vmcore: allocate buffer for ELF headers on page-size alignment HATAYAMA Daisuke
2013-03-16 4:01 ` [PATCH v3 06/21] vmcore: round up buffer size of ELF headers by PAGE_SIZE HATAYAMA Daisuke
2013-03-19 22:07 ` Eric W. Biederman
2013-03-16 4:01 ` [PATCH v3 07/21] vmcore, procfs: introduce a flag to distinguish objects copied in 2nd kernel HATAYAMA Daisuke
2013-03-19 19:35 ` Andrew Morton
2013-03-16 4:01 ` [PATCH v3 08/21] vmcore: copy non page-size aligned head and tail pages " HATAYAMA Daisuke
2013-03-19 19:37 ` Andrew Morton
2013-03-19 20:59 ` Eric W. Biederman
2013-03-19 21:22 ` Vivek Goyal [this message]
2013-03-19 23:35 ` Eric W. Biederman
2013-03-16 4:01 ` [PATCH v3 09/21] vmcore: modify vmcore clean-up function to free buffer on " HATAYAMA Daisuke
2013-03-16 4:01 ` [PATCH v3 10/21] vmcore: clean up read_vmcore() HATAYAMA Daisuke
2013-03-16 4:01 ` [PATCH v3 11/21] vmcore: read buffers for vmcore objects copied from old memory HATAYAMA Daisuke
2013-03-16 4:01 ` [PATCH v3 12/21] vmcore: allocate per-cpu crash_notes objects on page-size boundary HATAYAMA Daisuke
2013-03-19 21:06 ` Eric W. Biederman
2013-03-19 22:12 ` Eric W. Biederman
2013-03-20 13:48 ` Vivek Goyal
2013-03-20 20:48 ` Eric W. Biederman
2013-03-16 4:02 ` [PATCH v3 13/21] kexec: allocate vmcoreinfo note buffer " HATAYAMA Daisuke
2013-03-19 21:07 ` Eric W. Biederman
2013-03-19 22:12 ` Eric W. Biederman
2013-03-16 4:02 ` [PATCH v3 14/21] kexec, elf: introduce NT_VMCORE_DEBUGINFO note type HATAYAMA Daisuke
2013-03-16 4:02 ` [PATCH v3 15/21] elf: introduce NT_VMCORE_PAD type HATAYAMA Daisuke
2013-03-16 4:02 ` [PATCH v3 16/21] kexec: fill note buffers by NT_VMCORE_PAD notes in page-size boundary HATAYAMA Daisuke
2013-03-19 22:17 ` Eric W. Biederman
2013-03-16 4:02 ` [PATCH v3 17/21] vmcore: check NT_VMCORE_PAD as a mark indicating the end of ELF note buffer HATAYAMA Daisuke
2013-03-19 21:11 ` Eric W. Biederman
2013-03-21 2:59 ` HATAYAMA Daisuke
2013-03-21 3:54 ` Eric W. Biederman
2013-03-21 14:36 ` Vivek Goyal
2013-03-22 0:30 ` HATAYAMA Daisuke
2013-03-22 0:41 ` Eric W. Biederman
2013-03-19 22:20 ` Eric W. Biederman
2013-03-16 4:02 ` [PATCH v3 18/21] vmcore: check if vmcore objects satify mmap()'s page-size boundary requirement HATAYAMA Daisuke
2013-03-19 20:02 ` Andrew Morton
2013-03-19 21:22 ` Eric W. Biederman
2013-03-20 13:51 ` Vivek Goyal
2013-03-19 22:38 ` Eric W. Biederman
2013-03-20 13:57 ` Vivek Goyal
2013-03-20 20:55 ` Eric W. Biederman
2013-03-21 3:25 ` HATAYAMA Daisuke
2013-03-21 4:18 ` Eric W. Biederman
2013-03-21 6:14 ` HATAYAMA Daisuke
2013-03-21 6:29 ` Eric W. Biederman
2013-03-21 6:46 ` HATAYAMA Daisuke
2013-03-21 7:07 ` Eric W. Biederman
2013-03-21 15:21 ` Vivek Goyal
2013-03-21 15:27 ` Vivek Goyal
2013-03-22 0:43 ` HATAYAMA Daisuke
2013-03-22 0:54 ` Eric W. Biederman
2013-03-22 2:30 ` HATAYAMA Daisuke
2013-03-21 14:57 ` Vivek Goyal
2013-03-21 7:22 ` Eric W. Biederman
2013-03-21 14:49 ` Vivek Goyal
2013-03-22 7:11 ` HATAYAMA Daisuke
2013-03-21 13:50 ` Vivek Goyal
2013-03-16 4:02 ` [PATCH v3 19/21] vmcore: round-up offset of vmcore object in page-size boundary HATAYAMA Daisuke
2013-03-16 4:02 ` [PATCH v3 20/21] vmcore: count holes generated by round-up operation for vmcore size HATAYAMA Daisuke
2013-03-16 4:02 ` [PATCH v3 21/21] vmcore: introduce mmap_vmcore() HATAYAMA Daisuke
2013-03-19 19:30 ` [PATCH v3 00/21] kdump, vmcore: support mmap() on /proc/vmcore Andrew Morton
2013-03-21 3:52 ` HATAYAMA Daisuke
2013-03-21 6:16 ` Eric W. Biederman
2013-03-21 6:35 ` HATAYAMA Daisuke
2013-03-21 7:14 ` Eric W. Biederman
2013-03-19 23:16 ` Eric W. Biederman
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20130319212244.GE3872@redhat.com \
--to=vgoyal@redhat.com \
--cc=akpm@linux-foundation.org \
--cc=cpw@sgi.com \
--cc=d.hatayama@jp.fujitsu.com \
--cc=ebiederm@xmission.com \
--cc=heiko.carstens@de.ibm.com \
--cc=kexec@lists.infradead.org \
--cc=kumagai-atsushi@mxc.nes.nec.co.jp \
--cc=linux-kernel@vger.kernel.org \
--cc=lisa.mitchell@hp.com \
--cc=zhangyanfei@cn.fujitsu.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox