Re: [Xen-devel] xm save workaround

[John Croft <john@xxxxxxxxxxxxxxxx>]

found it !

xen-3.0.1-cloexec.patch in the source RPM for xen-3.0.1

John

John Croft wrote:

> Calling xc_interface_open returns a file descriptor which has had it's 
> close-on-exec flag set.
> Disassembling the code in xc_interface_open in libxenctrl.so as 
> shipped in the FC5 release has two calls to fcntl just after the 
> open.. GET_FD,  the flags, or in 1 and then SET_FD . This isn't in the 
> xc_misc.c in the repository, so I don't know how it's getting there.
> John
>
> Ewan Mellor wrote:
>
> > On Sat, Mar 25, 2006 at 09:04:40AM +0000, John Croft wrote:
> >
> >  
> >
> > > Hi all,
> > >
> > > This is something I posted earlier on Xen-Users. I understand it is 
> > > a known problem so you may be interested in this workaround.
> > > cheers,
> > > John
> > >
> > >
> > > Hi John-
> > >
> > > Thanks a lot, that did the trick.  Have you sent this to the Xen-Devel
> > > list?  If not, I bet they would be interested.
> > >
> > > Anyway, thanks again!
> > >
> > > -Patrick
> > >
> > > On 3/24/06, John Croft <john@xxxxxxxxxxxxxxxx> wrote:
> > >
> > >   
> > >
> > > > > Hi Patrick,
> > > > >
> > > > > I'm wondering if this is related to the problem I had and posted 
> > > > > on the
> > > > > xen-users list with a work-around. The symptoms are similar in that
> > > > > xm_save fails but the debug output is slightly different, but that 
> > > > > may
> > > > > be due to environmental differences.
> > > > >
> > > > > original post follows.
> > > > > John
> > > > >
> > > > > Hi all,
> > > > >
> > > > > Just installed Xen from the base FC5 released on Monday.
> > > > >
> > > > > It all seems to work great except for "xm save/migrate" which 
> > > > > fails with
> > > > > "Unable to get platform info.: 9" at XendCheckpoint:227.
> > > > >
> > > > > Playing around with it I found that there is a program called xc_save
> > > > > which is called from XendCheckpoint.py and passed in a file handle 
> > > > > for
> > > > > the xend session and the target file named on the command line. These
> > > > > handles seem to be closed when xc_save exec's, so subsequent calls 
> > > > > into
> > > > > Xen by xc_save fail. I got it to work by adding...
> > > > >
> > > > >  from fcntl import ioctl;
> > > > >  FIONCLEX = 0x5450
> > > > >
> > > > > near the top of XendCheckpoint.py
> > > > >
> > > > > and...
> > > > >
> > > > >  ioctl (fd, FIONCLEX, 0)
> > > > >  ioctl (xc.handle(), FIONCLEX, 0)
> > > > >
> > > > > at the beginning of forkHelper.
> > > > >       
> > This is clearing the close-on-exec flag for each of the file 
> > descriptors, so
> > import fcntl
> > ...
> > fcntl.fcntl(fd,          fcntl.F_SETFD, 0)
> > fcntl.fcntl(xc.handle(), fcntl.F_SETFD, 0)
> >
> > ought to do exactly the same, but be a little neater.
> >
> > What interests me though, is that these flags are set in the first 
> > place.  The
> > default is for this flag to be unset, and Xend is not setting the flag
> > explicitly on either of those file descriptors, so how did they get set?
> >
> > Could you investigate?
> >
> > Thanks,
> >
> > Ewan.
> >  
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