lkml.org 
[lkml]   [2019]   [Jan]   [14]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 1/2 v6] kdump: add the vmcoreinfo documentation



----- Original Message -----
> On Mon, Jan 14, 2019 at 01:58:32PM -0500, Dave Anderson wrote:
> > Preferably it would be left as-is. The crash utility has a "crash
> > --osrelease vmcore"
> > option that only looks at the dumpfile header, and just dump the string.
> > With respect
> > to compressed kdumps, crash could alternatively look at the utsname data
> > that is stored
> > in the diskdump_header.utsname field, but with ELF vmcores, there is no
> > such back-up.
>
> Well, there is:
>
> 00000000 4f 53 52 45 4c 45 41 53 45 3d 35 2e 30 2e 30 2d |OSRELEASE=5.0.0-|
> 00000010 72 63 32 2b 0a 50 41 47 45 53 49 5a 45 3d 34 30 |rc2+.PAGESIZE=40|
> 00000020 39 36 0a 53 59 4d 42 4f 4c 28 6d 65 6d 5f 73 65 |96.SYMBOL(mem_se|
> 00000030 63 74 69 6f 6e 29 3d 66 66 66 66 66 66 66 66 38 |ction)=ffffffff8|
> 00000040 34 35 31 61 31 61 38 0a 53 59 4d 42 4f 4c 28 69 |451a1a8.SYMBOL(i|
> 00000050 6e 69 74 5f 75 74 73 5f 6e 73 29 3d 66 66 66 66 |nit_uts_ns)=ffff|
> ^^^^
> 00000060 66 66 66 66 38 32 30 31 33 35 34 30 0a 53 59 4d |ffff82013540
> ^^^^^^^^^^^^
>
> This address has it.

There's no reading of the dumpfile's memory involved, and that being the case,
the vmlinux file is not utilized. That's the whole point of the crash option, i.e.,
taking a vmcore file, and trying to determine what kernel should be used with it:

$ man crash
...
--osrelease dumpfile
Display the OSRELEASE vmcoreinfo string from a kdump dumpfile header.
...


>
> > What's the problem with leaving it alone?
>
> The problem is that I'd like to get all those vmcoreinfo exports under
> control and to not have people frivolously export whatever they feel
> like, for obvious reasons, and to get rid of the duplicate/unused pieces
> being part of vmcoreinfo.

Well, I just don't agree that the OSRELEASE item is "frivolous". It's been in place,
and depended upon, for many years.

Dave

\
 
 \ /
  Last update: 2019-01-14 20:37    [W:0.071 / U:26.540 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site