Hi Petr, On Thu, Nov 13, 2014 at 04:51:48PM +0100, Petr Tesarik wrote: > Hi all, > > this thread got somehow forgotten because of vacations... > Anyway, read below. > > On Tue, 24 Jul 2012 15:54:10 +0200 > Daniel Kiper <daniel.kiper at oracle.com> wrote: > > > On Tue, Jul 24, 2012 at 10:18:34AM +0200, Petr Tesarik wrote: > > > Dne Po 23. ??ervence 2012 22:10:59 Daniel Kiper napsal(a): > > > > Hi Petr, > > > > > > > > On Mon, Jul 23, 2012 at 03:30:55PM +0200, Petr Tesarik wrote: > > > > > Dne Po 23. ??ervence 2012 14:56:07 Petr Tesarik napsal(a): > > > > > > Dne ??t 5. ??ervence 2012 14:16:35 Daniel Kiper napsal(a): > > > > > > > vmcoreinfo file could exists under /sys/kernel (valid on baremetal > > > > > > > only) and/or under /sys/hypervisor (valid when Xen dom0 is running). > > > > > > > Read only one of them. It means that only one PT_NOTE will be always > > > > > > > created. Remove extra code for second PT_NOTE creation. > > > > > > > > > > > > Hi Daniel, > > > > > > > > > > > > are you absolutely sure this is the right thing to do? IIUC these two > > > > > > VMCORINFO notes are very different. The one from /sys/kernel/vmcoreinfo > > > > > > describes the Dom0 kernel (type 'VMCOREINFO'), while the one from > > > > > > /sys/hypervisor describes the Xen hypervisor (type 'XEN_VMCOREINFO'). > > > > > > If you keep only the hypervisor note, then e.g. makedumpfile won't be > > > > > > able to use dumplevel greater than 1, nor will it be able to extract > > > > > > the log buffer. > > > > > > > > > > I've just verified this, and I'm confident we have to keep both notes in > > > > > the dump file. Simon, please revert Daniel's patch to avoid regressions. > > > > > > > > > > I'm attaching a sample VMCOREINFO_XEN and VMCOREINFO to demonstrate the > > > > > difference. Note that the VMCOREINFO_XEN note is actually too big, > > > > > because Xen doesn't bother to maintain the correct note size in the note > > > > > header, so it always spans a complete page minus sizeof(Elf64_Nhdr)... > > > > > > > > [...] > > > > > > > > The problem with /sys/kernel/vmcoreinfo under Xen is that it expose invalid > > > > physical address. It breaks /proc/vmcore in crash kernel. That is why I > > > > proposed that fix. Additionally, /sys/kernel/vmcoreinfo is not available > > > > under Xen Linux Ver. 2.6.18. However, I did not do any makedumpfile tests. > > > > If you discovered any issues with my patch please drop me more details > > > > about your tests (Xen version, Linux Kernel version, makedumpfile version, > > > > command lines, config files, logs, etc.). I will be more then happy to > > > > fix/improve kexec-tools and makedumpfile. > > > > > > Hi Daniel, > > > > > > well, Linux v2.6.18 does not have /sys/kernel/vmcoreinfo, simply because the > > > VMCOREINFO infrastructure was not present in 2.6.18. It was added later with > > > > Yep. > > > > > commit fd59d231f81cb02870b9cf15f456a897f3669b4e, which went into 2.6.24. > > > > Hmmm... As I know 2.6.24 does not support kexec/kdump under Xen dom0. Correct? > > > > > I tested with the following combinations: > > > > > > * xen-3.3.1 + kernel-xen-2.6.27.54 + kexec-tools-2.0.0 + makedumpfile-1.3.1 > > > * xen-4.0.3 + kernel-xen-2.6.32.59 + kexec-tools-2.0.0 + makedumpfile-1.3.1 > > > * xen-4.1.2 + kernel-xen-3.0.34 + kexec-tools-2.0.0 + makedumpfile-1.4.0 > > > > > > These versions correspond to SLES11-GA, SLES11-SP1 and SLES11-SP2, > > > respectively. All of them work just fine and save both ELF notes into the > > > dump. > > > > Could you test current kexec-tools development version and > > latest makedumpfile version on latest SLES version? > > And indeed, I've just hit this regression with SLES12 GA (kernel 3.12.28, > kexec-tools 2.0.5, makedumpfile 1.5.6). > > In the secondary kernel, makedumpfile complains that VMCOREINFO is not > stored in /proc/vmcore: > > bash-4.2# makedumpfile -d 31 -X -E /proc/vmcore /kdump/mnt1/abuild/dumps/2014-11-13-13\:13/vmcore.elf > Switched running mode from cyclic to non-cyclic, > because the cyclic mode doesn't support Xen. > /proc/vmcore doesn't contain vmcoreinfo. > Specify '-x' option or '-i' option. > Commandline parameter is invalid. > Try `makedumpfile --help' for more information. > > makedumpfile Failed. > > Then I reverted commit 455d79f57e9367e5c59093fd74798905bd5762fc and > everything works just fine. > > > > What do you mean by "invalid physical address"? I'm getting the correct > > > physical address under Xen. Obviously, it must be translated to machine > > > addresses if you need them from the secondary kernel. > > > > Correct vmcoreinfo address should be established by calling > > HYPERVISOR_kexec_op(KEXEC_CMD_kexec_get_range, KEXEC_RANGE_MA_VMCOREINFO). > > The addresses I get from /sys/kernel/vmcoreinfo and > from /sys/hypervisor/vmcoreinfo are machine addresses in both cases, so > when a non-Xen kernel is used for dumping, everything works as expected. > > I am well aware that the Xen implementation in SLES differs > substantially from mainline, but it seems to me that: > > 1. both VMCOREINFO and VMCOREINFO_XEN is required for dumpfile > filtering, and > 2. both sysfs files should report machine addresses, because the current > p2m mapping is lost forever when the hypervisor executes the secondary > kernel, so physical addresses are pretty useless. > > I'm reverting the patch for the SLES distro, but I'd like to reach some > kind of consensus with the community, too. This reminds me something. I saw that kind of thing when I was working on makedumpfile once. I have this issue on my TODO list. However, currently I am working on EFI and multiboot2 stuff and I am not able to take a look at it. I will do that after releasing first version of patches. Probably in the middle of December. Is it OK for you? Daniel
