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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: Troubles analyzing crash dumps from xl dump-core
On 30.01.21 19:53, Roman Shaposhnik wrote: On Fri, Jan 29, 2021 at 11:28 PM Jürgen Groß <jgross@xxxxxxxx> wrote:On 29.01.21 21:12, Roman Shaposhnik wrote:Hi! I'm trying to see how much mileage I can get out of crash(1) 7.2.8 (based on gdb 7.6) when it comes to analyzing crash dumps taken via xl dump-core (this is all on x86_64 with stock Xen v. 4.14). The good news is that the image actually does load up but it throws the following WARNINGs in the process: WARNING: cannot access vmalloc'd module memory crash: read error: kernel virtual address: ffffffff93613480 type: "fill_task_struct" WARNING: active task ffffffff93613480 on cpu 0 not found in PID hash crash: read error: kernel virtual address: ffffffff93613480 type: "fill_task_struct" WARNING: cannot read log_buf contents And then the info that it gives me around basic things like ps, mod, log, etc. is really super limited (and I am now suspecting may even be wrong). Since I was primarily after dmesg/log initially, I tried: crash> log log: WARNING: cannot read log_buf contents Then I tried taking an xl dump-core from the domU that was still very much alive and happy and got similar results -- so it clearly doesn't seem to be related to the state domU is in. As matter of fact, I actually got to the desired dmesg output by simply running strings(1) on the core file -- so the info is definitely there -- but I guess some kind of index/reference maybe broken. With all that in mind, if there's anyone on this ML who has recently done Xen DomU crash dump analysis -- I would definitely appreciate the pointers!For me it just works (openSUSE).Can you please run: crash --version and readelf -a XXXX (on the xl dump-core output) and post the results? # crash --version crash 7.2.1 Copyright (C) 2002-2017 Red Hat, Inc. Copyright (C) 2004, 2005, 2006, 2010 IBM Corporation Copyright (C) 1999-2006 Hewlett-Packard Co Copyright (C) 2005, 2006, 2011, 2012 Fujitsu Limited Copyright (C) 2006, 2007 VA Linux Systems Japan K.K. Copyright (C) 2005, 2011 NEC Corporation Copyright (C) 1999, 2002, 2007 Silicon Graphics, Inc. Copyright (C) 1999, 2000, 2001, 2002 Mission Critical Linux, Inc. This program is free software, covered by the GNU General Public License, and you are welcome to change it and/or distribute copies of it under certain conditions. Enter "help copying" to see the conditions. This program has absolutely no warranty. Enter "help warranty" for details. GNU gdb (GDB) 7.6 Copyright (C) 2013 Free Software Foundation, Inc.License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law. Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-unknown-linux-gnu".
# readelf -a pv-dump
ELF Header:
Magic: 7f 45 4c 46 02 01 01 00 01 00 00 00 00 00 00 00
Class: ELF64
Data: 2's complement, little endian
Version: 1 (current)
OS/ABI: UNIX - System V
ABI Version: 1
Type: CORE (Core file)
Machine: Advanced Micro Devices X86-64
Version: 0x1
Entry point address: 0x0
Start of program headers: 0 (bytes into file)
Start of section headers: 64 (bytes into file)
Flags: 0x0
Size of this header: 64 (bytes)
Size of program headers: 56 (bytes)
Number of program headers: 0
Size of section headers: 64 (bytes)
Number of section headers: 7
Section header string table index: 1
Section Headers:
[Nr] Name Type Address Offset
Size EntSize Flags Link Info Align
[ 0] NULL 0000000000000000 00000000
0000000000000000 0000000000000000 0 0 0
[ 1] .shstrtab STRTAB 0000000000000000 40404000
0000000000000048 0000000000000000 0 0 0
[ 2] .note.Xen NOTE 0000000000000000 00000200
0000000000000568 0000000000000000 0 0 0
[ 3] .xen_prstatus PROGBITS 0000000000000000 00000768
0000000000002860 0000000000001430 0 0 8
[ 4] .xen_shared_info PROGBITS 0000000000000000 00002fc8
0000000000001000 0000000000001000 0 0 8
[ 5] .xen_pages PROGBITS 0000000000000000 00004000
0000000040000000 0000000000001000 0 0 4096
[ 6] .xen_p2m PROGBITS 0000000000000000 40004000
0000000000400000 0000000000000010 0 0 8
Key to Flags:
W (write), A (alloc), X (execute), M (merge), S (strings), I (info),
L (link order), O (extra OS processing required), G (group), T (TLS),
C (compressed), x (unknown), o (OS specific), E (exclude),
l (large), p (processor specific)
There are no section groups in this file.
There are no program headers in this file.
There is no dynamic section in this file.
There are no relocations in this file.
The decoding of unwind sections for machine type Advanced Micro Devices
X86-64 is not currently supported.
No version information found in this file. No note segments present in the core file. also, what version of Xen are you using? Current staging branch. I tried a pv guest only with a 4.4 kernel, though.I would really appreciate it if you could try it on HVM so that I know whether it is an issue that only affects my setup or other folks (especially after seeing answers to above).
Works as well.
# readelf -a hvm-dump
ELF Header:
Magic: 7f 45 4c 46 02 01 01 00 01 00 00 00 00 00 00 00
Class: ELF64
Data: 2's complement, little endian
Version: 1 (current)
OS/ABI: UNIX - System V
ABI Version: 1
Type: CORE (Core file)
Machine: Advanced Micro Devices X86-64
Version: 0x1
Entry point address: 0x0
Start of program headers: 0 (bytes into file)
Start of section headers: 64 (bytes into file)
Flags: 0x0
Size of this header: 64 (bytes)
Size of program headers: 56 (bytes)
Number of program headers: 0
Size of section headers: 64 (bytes)
Number of section headers: 7
Section header string table index: 1
Section Headers:
[Nr] Name Type Address Offset
Size EntSize Flags Link Info Align
[ 0] NULL 0000000000000000 00000000
0000000000000000 0000000000000000 0 0 0
[ 1] .shstrtab STRTAB 0000000000000000 8044f260
0000000000000048 0000000000000000 0 0 0
[ 2] .note.Xen NOTE 0000000000000000 00000200
0000000000000568 0000000000000000 0 0 0
[ 3] .xen_prstatus PROGBITS 0000000000000000 00000768
0000000000001430 0000000000001430 0 0 8
[ 4] .xen_shared_info PROGBITS 0000000000000000 00001b98
0000000000001000 0000000000001000 0 0 8
[ 5] .xen_pages PROGBITS 0000000000000000 00003000
000000008004c000 0000000000001000 0 0 4096
[ 6] .xen_pfn PROGBITS 0000000000000000 8004f000
0000000000400260 0000000000000008 0 0 8
Key to Flags:
W (write), A (alloc), X (execute), M (merge), S (strings), I (info),
L (link order), O (extra OS processing required), G (group), T (TLS),
C (compressed), x (unknown), o (OS specific), E (exclude),
l (large), p (processor specific)
There are no section groups in this file.
There are no program headers in this file.
There is no dynamic section in this file.
There are no relocations in this file.
The decoding of unwind sections for machine type Advanced Micro Devices
X86-64 is not currently supported.
No version information found in this file. No note segments present in the core file. Juergen Attachment:
OpenPGP_0xB0DE9DD628BF132F.asc Attachment:
OpenPGP_signature
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