Re: port-xen/55207 (netbsd domU does not migrate properly from one xen host to another)

[Pierre-Philipp Braun <pbraun%nethence.com@localhost>]

Thank you Jaromír for your improvements on hot-migrating netbsd XEN/PV domUs.  Even though it is not finalized, I tried again with v9 vs daily build HEAD/202008060510Z and here are the results.  I don't know if that matters but for the record, those new tests have been done on top of NFSv3 vdisk ext4 sparse files, with a fake /dev/ on tmpfs, a fictitious disk label and FFS2 as root file-system created by makefs from netbsd's cross-compilation toolchain on linux.

with v9

root@slack2hb:~/guests/slime9# xl save slime9 slime9.save
Saving to slime9.save new xl format (info 0x3/0x0/1497)
xc: info: Saving domain 18, type x86 PV
xc: error: save callback suspend() failed: 0: Internal error
xc: error: Save failed (0 = Success): Internal error
libxl: error: libxl_stream_write.c:350:libxl__xc_domain_save_done: Domain 18:saving domain: domain responded to suspend request: Success
Failed to save domain, resuming domain
libxl: error: libxl_dom.c:40:libxl__domain_type: unable to get domain type for domid=18

[  63.5605882] xenbus_shutdown_handler: xenbus_rm 13
[  63.5803786] Flushing disk caches: 8 done
[  63.6004200] fatal page fault in supervisor mode
[  63.6004200] trap type 6 code 0 rip 0xffffffff8020313f cs 0xe030 rflags 0x10256 cr2 0x10 ilevel 0x6 rsp
0xffffd2004c92fd58
[  63.6004200] curlwp 0xffffd20001d1d480 pid 0.3 lowest kstack 0xffffd2004c92c2c0
[  63.6004200] panic: trap
[  63.6004200] cpu0: Begin traceback...
[  63.6004200] vpanic() at netbsd:vpanic+0x143
[  63.6004200] snprintf() at netbsd:snprintf
[  63.6004200] startlwp() at netbsd:startlwp
[  63.6004200] alltraps() at netbsd:alltraps+0xae
[  63.6004200] softint_thread() at netbsd:softint_thread+0x117
[  63.6004200] cpu0: End traceback...

[  63.6004200] dumping to dev 142,1 (offset=0, size=0): not possible
[  63.6004200] rebooting...

with current

root@slack2hb:~/guests/slime# xl save slime slime.save
Saving to slime.save new xl format (info 0x3/0x0/1479)
xc: info: Saving domain 20, type x86 PV
xc: Frames: 262144/262144  100%
xc: error: Bad mfn for suspend record: Internal error
xc: error: mfn 0x7f7fff4cb7e0, max 0x2030000: Internal error
xc: error: Save failed (34 = Numerical result out of range): Internal error
libxl: error: libxl_stream_write.c:350:libxl__xc_domain_save_done: Domain 20:saving domain: domain responded to suspend request: Numerical result out of range
Failed to save domain, resuming domain

[  19.2002331] Flushing disk caches: done
[  19.7401533] uvm_fault(0xffffffff808a8200, 0xffffffff80baf000, 2) -> e
[  19.7401533] fatal page fault in supervisor mode
[  19.7401533] trap type 6 code 0x2 rip 0xffffffff806034a9 cs 0xe030 rflags 0x10202 cr2 0xffffffff80baf001 ilevel 0 rsp 0xffffb7805d508e70
[  19.7401533] curlwp 0xffffb78002ad9a00 pid 827.827 lowest kstack 0xffffb7805d5042c0
[  19.7401533] panic: trap
[  19.7401533] cpu0: Begin traceback...
[  19.7401533] vpanic() at netbsd:vpanic+0x146
[  19.7401533] snprintf() at netbsd:snprintf
[  19.7401533] startlwp() at netbsd:startlwp
[  19.7401533] cpu0: End traceback...

[  19.7401533] dumping to dev 142,1 (offset=0, size=0): not possible
[  19.7401533] rebooting...

I am not sure how to interpret this but I hope it's useful.