Re: [Xen-devel] kexec and kdump on Xen??

[Daniel Kiper <dkiper@xxxxxxxxxxxx>]

On Tue, Apr 15, 2014 at 02:13:56AM +0000, Zhang, Yang Z wrote:
> Daniel Kiper wrote on 2014-04-14:
> > Hey,
> >
> > On Mon, Apr 14, 2014 at 08:15:35AM +0000, Zhang, Yang Z wrote:
> >> Daniel Kiper wrote on 2014-04-14:
> >>> Hi,
> >>>
> >>> On Mon, Apr 14, 2014 at 03:38:26AM +0000, Zhang, Yang Z wrote:
> >>>> Hi Daniel
> >>>>
> >>>> Are kexec/kdump supported by latest Xen + upstream Linux?
> >>>> I remember it only works with xen+2.6.18 linux. I know you are
> >>>> working on enable it. So I wonder to know what the current status is.
> > Thanks.
> >>>
> >>> Xen 4.4 has new kexec implementation written by David Vrabel.
> >>> It does not require any specific Linux Kernel version because this
> >>> implementation is self contained. However, please do not forget to
> >>> use
> >>
> >> Cool..
> >>
> >>> latest stable version of kexec-tools too.
> >>
> >> Is there any BKM to use it? I saw an old wiki page but not sure
> >> whether it is still suitable.
> >
> > I assume that you are asking about kexec/kdump support in dom0.
> >
> > Just build kexec-tools with Xen support enabled (you must provide
> > relevant Xen header files and libraries).
> > Then add crashkernel argument to Xen (e.g. crashkernel=512m@64m) and
> > reboot machine. Use kexec-tools like on bare metal machines.
>
> I am trying to kexec from Xen to Linux. But it fails to work.
> ./kexec -l /boot/vmlinuz-2.6.32-358.el6.x86_64

What about --append or --command-line?

> kexec_load failed: Invalid argument
> entry       = 0x7fff6760 flags = 0x3e0000
> nr_segments = 3
> segment[0].buf   = 0x138f660
> segment[0].bufsz = 0x3641
> segment[0].mem   = 0x3000
> segment[0].memsz = 0x4000
> segment[1].buf   = 0x7fc68badf610
> segment[1].bufsz = 0x3d8110
> segment[1].mem   = 0x1000000
> segment[1].memsz = 0x3d9000
> segment[2].buf   = 0x1387540
> segment[2].bufsz = 0x80e0
> segment[2].mem   = 0x7fff6000
> segment[2].memsz = 0xa000

Could you configure kexec-tools in following way:

./configure CFLAGS=-DDEBUG

Then build it as usual.

> Here is my environment:
> Xen version: latest Xen
> Xen boot command:
>       kernel (hd0,0)/boot/xen.gz dom0_mem=4096M loglvl=all guest_loglvl=all 
> conring_size=4M crashkernel=128M@64M
>     module (hd0,0)/boot/vmlinuz-xen o 
> root=UUID=03a5e7c4-b8d0-45b4-a090-c34b06821cea pci=noaer max_loop=64 3 debug
>     module (hd0,0)/boot/initrd-xen.img
> kexec version with Xen enabled:  kexec-tools 2.0.6 released 18 April 2014
>
> Also, it shows error when trying to kexec (Xen -> Xen)
> ./kexec -l /boot/xen.gz
> Segmentation fault (core dumped)

We were focusing more on kdump than on other scenarios.
I suppose that kexec-tools assume that this compressed
ELF file is Linux Kernel and tries load it as usual which
of course is completely wrong. You should load Xen with
at least "-t multiboot-x86" argument (read help printed
by kexec). However, I am not sure that this loader
is actively maintained and works.

Daniel

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel