Xen devel - Jan 2013 - Modifying Xen migration

Hello everyone,
for research purposes I''m working on Xen 3.0.3 and trying to make some
modifications to Xen migration. By looking at the documentation, I''ve
learned that the part I''m interesting in are handled by two binaries
(xc_save and xc_restore), so I thought about modifying just this two
binaries instead of recompiling the whole Xen everytime, so what I do
is just modifying this two binaries, recompile them with "make tools"
and then copy them into /usr/lib64/xen/bin/ . However, after doing
this, when running the migration command (xm migrate domain
destination) I got a popen error. What am I doing wrong? Please have a
look at the log below if it could be useful. Thanks a lot in advance!

Traceback (most recent call last):
  File
"/usr/lib64/python2.4/site-packages/xen/xend/XendCheckpoint.py",
line 211, in save
    forkHelper(cmd, fd, saveInputHandler, False, dominfo)
  File
"/usr/lib64/python2.4/site-packages/xen/xend/XendCheckpoint.py",
line 477, in forkHelper
    raise XendError("%s failed: popen failed" % string.join(cmd))
XendError: /usr/lib64/xen/bin/xc_save 23 1385 0 0 4 failed: popen failed
[2013-01-18 15:54:48 xend.XendDomainInfo 11608] DEBUG
(XendDomainInfo:2403) XendDomainInfo.resumeDomain(1385)
[2013-01-18 15:54:48 xend 11608] DEBUG (XendCheckpoint:240)
XendCheckpoint.save: resumeDomain
[2013-01-18 15:54:48 xend 11608] DEBUG (DevController:571)
hotplugStatusCallback
/local/domain/0/backend/vif/1385/0/hotplug-status.
[2013-01-18 15:54:48 xend 11608] DEBUG (DevController:585)
hotplugStatusCallback 1.
[2013-01-18 15:54:48 xend 11608] DEBUG (DevController:571)
hotplugStatusCallback
/local/domain/0/backend/vbd/1385/768/hotplug-status.
[2013-01-18 15:54:48 xend 11608] DEBUG (DevController:585)
hotplugStatusCallback 1.
[2013-01-18 15:54:48 xend 11608] DEBUG (DevController:571)
hotplugStatusCallback
/local/domain/0/backend/vbd/1385/5632/hotplug-status.
[2013-01-18 15:54:48 xend 11608] DEBUG (DevController:585)
hotplugStatusCallback 1.
[2013-01-18 15:56:53 xend 11608] DEBUG (XendCheckpoint:188) [xc_save]:
/usr/lib64/xen/bin/xc_save 22 1385 0 0 5
[2013-01-18 15:56:54 xend 11608] INFO (XendCheckpoint:511)
/usr/lib64/xen/bin/xc_save: symbol lookup error:
/usr/lib64/xen/bin/xc_save: undefined symbol: xc_linux_
[2013-01-18 15:56:54 xend 11608] ERROR (XendCheckpoint:236) Save
failed on domain system1 (1385).
Traceback (most recent call last):
  File
"/usr/lib64/python2.4/site-packages/xen/xend/XendCheckpoint.py",
line 211, in save
    forkHelper(cmd, fd, saveInputHandler, False, dominfo)
  File
"/usr/lib64/python2.4/site-packages/xen/xend/XendCheckpoint.py",
line 477, in forkHelper
    raise XendError("%s failed: popen failed" % string.join(cmd))
XendError: /usr/lib64/xen/bin/xc_save 22 1385 0 0 5 failed: popen failed
[2013-01-18 15:56:54 xend.XendDomainInfo 11608] DEBUG
(XendDomainInfo:2403) XendDomainInfo.resumeDomain(1385)
[2013-01-18 15:56:54 xend 11608] DEBUG (XendCheckpoint:240)
XendCheckpoint.save: resumeDomain
[2013-01-18 15:56:54 xend 11608] DEBUG (DevController:571)
hotplugStatusCallback
/local/domain/0/backend/vif/1385/0/hotplug-status.
[2013-01-18 15:56:54 xend 11608] DEBUG (DevController:585)
hotplugStatusCallback 1.
[2013-01-18 15:56:54 xend 11608] DEBUG (DevController:571)
hotplugStatusCallback
/local/domain/0/backend/vbd/1385/768/hotplug-status.
[2013-01-18 15:56:54 xend 11608] DEBUG (DevController:585)
hotplugStatusCallback 1.
[2013-01-18 15:56:54 xend 11608] DEBUG (DevController:571)
hotplugStatusCallback
/local/domain/0/backend/vbd/1385/5632/hotplug-status.
[2013-01-18 15:56:54 xend 11608] DEBUG (DevController:585)
hotplugStatusCallback 1.

On Sun, 2013-01-27 at 14:26 +0000, Vincenzo De Maio
wrote:
> Hello everyone,
> for research purposes I''m working on Xen 3.0.3 and trying to make
some
> modifications to Xen migration.
That''s a very old version of Xen -- any reason you can''t use
something
more modern like 4.1 or 4.2?
>  By looking at the documentation, I''ve
> learned that the part I''m interesting in are handled by two
binaries
> (xc_save and xc_restore),
These are used by the xend toolstack only, and are fairly thin wrappers
around tools/libxc/xc_domain_{save,restore}.c. Other toolstacks (which
likely aren''t an issue with 3.0.3 but...) use libxc directly.
>  so I thought about modifying just this two
> binaries instead of recompiling the whole Xen everytime, so what I do
> is just modifying this two binaries, recompile them with "make
tools"
> and then copy them into /usr/lib64/xen/bin/ . However, after doing
> this, when running the migration command (xm migrate domain
> destination) I got a popen error. What am I doing wrong?
You new binaries do not work, as you can see in the log.
>  Please have a
> look at the log below if it could be useful. Thanks a lot in advance!
> 
> Traceback (most recent call last):
>   File
"/usr/lib64/python2.4/site-packages/xen/xend/XendCheckpoint.py",
> line 211, in save
>     forkHelper(cmd, fd, saveInputHandler, False, dominfo)
>   File
"/usr/lib64/python2.4/site-packages/xen/xend/XendCheckpoint.py",
> line 477, in forkHelper
>     raise XendError("%s failed: popen failed" % string.join(cmd))
> XendError: /usr/lib64/xen/bin/xc_save 23 1385 0 0 4 failed: popen failed
[...]
> /usr/lib64/xen/bin/xc_save: symbol lookup error:
> /usr/lib64/xen/bin/xc_save: undefined symbol: xc_linux_
This is your error. Almost certainly thise relates to whatever
modification you have made.

Ian.