[Xen-devel] Re: Test results for save/restore with upstream pv_ops domU kernels

[Pasi Kärkkäinen <pasik@xxxxxx>]

On Fri, Jan 29, 2010 at 10:35:32AM +0000, Ian Campbell wrote:
> On Thu, 2010-01-28 at 21:25 +0000, Pasi Kärkkäinen wrote:
> > Hello,
> > 
> > I just tried some save/restore tests with Fedora 12 Linux 2.6.31.12 kernels.
> > The exact Fedora kernel versions are: 2.6.31.12-174.2.3.fc12.i686.PAE and 
> > 2.6.31.12-174.2.3.fc12.x86_64.
> > 
> > Dom0 for these tests was CentOS 5.4 (Xen 3.1.2).
> > 
> > - F12 32bit 1vcpu PV guest: 
> >     save+restore OK, BUG() in guest dmesg after restore [1]
> > 
> > - F12 64bit 1vcpu PV guest:
> >     save+restore OK, BUG() in guest dmesg after restore [2]
> 
> I think those are the same underlying bug and are fixed by 
> http://git.kernel.org/?p=linux/kernel/git/jeremy/xen.git;a=commit;h=777df2b017ef34b2d1a172bf769582158839a860
> 

Ok. 

There was also this traceback in the beginning of boot, on all 32bit/64bit, 
1vcpu2/vcpu guest combinations:

Performance Counters: Core2 events, Intel PMU driver.
------------[ cut here ]------------
WARNING: at arch/x86/kernel/apic/apic.c:247 native_apic_write_dummy+0x32/0x3e() 
(Not tainted)
Modules linked in:
Pid: 0, comm: swapper Not tainted 2.6.31.12-174.2.3.fc12.i686.PAE #1
Call Trace:
 [<c043db4b>] warn_slowpath_common+0x70/0x87
 [<c041cfb2>] ? native_apic_write_dummy+0x32/0x3e
 [<c043db74>] warn_slowpath_null+0x12/0x15
 [<c041cfb2>] native_apic_write_dummy+0x32/0x3e
 [<c0411e04>] perf_counters_lapic_init+0x30/0x32
 [<c09b3b1b>] init_hw_perf_counters+0x2bc/0x355
 [<c09b3628>] identify_boot_cpu+0x21/0x23
 [<c09b378e>] check_bugs+0xb/0xdc
 [<c047fd73>] ? delayacct_init+0x47/0x4c
 [<c09ab8b4>] start_kernel+0x31c/0x330
 [<c09ab081>] i386_start_kernel+0x70/0x77
 [<c09ae2bb>] xen_start_kernel+0x4b9/0x4c1
 [<c04090a1>] ? syscall_exit+0x1/0x16
---[ end trace a7919e7f17c0a725 ]---

Full boot logs here:
http://pasik.reaktio.net/xen/debug/fedora/


> > 
> > - F12 32bit 2vcpu PV guest:
> >     save doesn't work, guest stays as "migrating-f12test32" in "xm list" 
> > forever and has to be "xm destroy"ed.
> > 
> > - F12 64bit 2vcpu PV guest:
> >     save doesn't work, guest stays as "migrating-f12test64" in "xm list" 
> > forever and has to be "xm destroy"ed.
> > 
> > 
> > What's the best way to debug failing "xm save" ? There was no errors in "xm 
> > log", or in "xm dmesg".
> 
> I think you might see some stuff in /var/log/xen/something but I don't
> have any particular tips apart from "add printf/printk".
> 

I'll check /var/log/xen/.

> > Also the guest "xm console" doesn't show anything before it dies.
> > 
> > Is it possible some of the save/restore related patches didn't make it to 
> > 2.6.31.x stable kernels? 
> 
> AFAIK they only went into the 2.6.32 stable branch. Unfortunately I
> think the 2.6.31 stable series has come to an end now.
> 

Ok. I'll test 2.6.32.latest aswell.

-- Pasi


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