RE: [Xen-devel] blktap2: need more than 3 values to unpack

[Dan Magenheimer <dan.magenheimer@xxxxxxxxxx>]

Thanks.  Looks like a partial configuration patch got checked
in for blktap2 (cs 886)?  CONFIG_XEN_BLKDEV_TAP2 must be configured
but afaict is not turned on by default (yet?).  So a fresh
xen-unstable tip doesn't build the blktap2 driver.  See:

http://xenbits.xensource.com/linux-2.6.18-xen.hg?rev/3e01555dd227

(I'm guessing since this was submitted by Isaku that blktap2
shouldn't be the default on ia64?)

Should CONFIG_XEN_BLKDEV_TAP2 be turned on by default, instead
of CONFIG_XEN_BLKDEV_TAP, at least on x86?

I tried modifying

linux-2.6.18-xen.hg/buildconfigs/linux-defconfig_xen0_x86_32

(and also

linux-2.6.18-xen.hg/buildconfigs/linux-defconfig_xen_x86_32)

followed by:

KERNELS=linux-2.6-xen0 make linux-2.6-xen-config CONFIGMODE=oldconfig

(I don't need or want to go through a manual config process)

but BLKDEV_TAP is always selected, not BLKDEV_TAP2.

Finally, I resorted to manually changing

linux-2.6.18-xen.hg/drivers/xen/Kconfig

and this succeeds in turning it on, but it just reverses the
above checked-in patch, so I suspect that's not the right
answer either.

> -----Original Message-----
> From: Dutch Meyer [mailto:dmeyer@xxxxxxxxx]
> Sent: Tuesday, June 02, 2009 9:05 AM
> To: Dan Magenheimer
> Subject: RE: [Xen-devel] blktap2: need more than 3 values to unpack
> 
> 
> I think that you don't have the blktap2 driver loaded in 
> dom0.  A clean 
> build/install of the dom0 kernel image should sort you out.  If 
> drivers/xen/blktap2 is compiled in it should be setting up 
> these paths.
> 
> Let me know if that fixes things and I'll make python spit out more 
> meaningful errors, otherwise we can try to figure out the 
> blktap2 kernel 
> code isn't working.
> 
> --Dutch
> 
> On Tue, 2 Jun 2009, Dan Magenheimer wrote:
> 
> > It replies with "didn't find blktap-control in /proc/misc"
> >
> > If that fails, perhaps the path doesn't exist, but I looked
> > and /sys/class/blktap2 doesn't exist.
> >
> >> -----Original Message-----
> >> From: Dutch Meyer [mailto:dmeyer@xxxxxxxxx]
> >> Sent: Monday, June 01, 2009 10:37 PM
> >> To: Dan Magenheimer
> >> Subject: RE: [Xen-devel] blktap2: need more than 3 values to unpack
> >>
> >>
> >> Can you try this from the command line:
> >>
> >>      tapdisk2 -n aio:/pathto/file.img
> >>
> >> If successful, this will create your aio device and print a
> >> /dev device
> >> associated with it.
> >>
> >> In that case you'll then be able to remove it with:
> >>
> >>      echo 1 > /sys/class/blktap2/<disk>/remove
> >>
> >> Where <disk> will be obvious from the output of the 
> tapdisk2 command.
> >>
> >> However, I expect that this will fail.
> >>
> >> --Dutch
> >>
> >> On Mon, 1 Jun 2009, Dan Magenheimer wrote:
> >>
> >>>> Then I might be able to help, but I'm not sure how to
> >>>> reproduce it.  If
> >>>> you send a log file and config for this latter error I'll
> >>>> take a look.
> >>>
> >>> Here ya go.
> >>>
> >>> Thanks,
> >>> Dan
> >>>
> >>>> -----Original Message-----
> >>>> From: Dutch Meyer [mailto:dmeyer@xxxxxxxxx]
> >>>> Sent: Monday, June 01, 2009 8:32 PM
> >>>> To: Dan Magenheimer
> >>>> Cc: Xen-Devel (E-mail)
> >>>> Subject: Re: [Xen-devel] blktap2: need more than 3 
> values to unpack
> >>>>
> >>>>
> >>>> The tap:aio:/pathto/file.img syntax that you're using in your
> >>>> config was
> >>>> changed before blktap2 was introduced.
> >>>> tap:tapdisk:aio:/pathto/file.img is
> >>>> apparently the correct syntax now, though the README didn't
> >>>> get updated to
> >>>> reflect this.  Our blktap2 documentation is no better - 
> I'll try to
> >>>> remedy that this week.
> >>>>
> >>>>
> >>>> If you're still seeing this error:
> >>>>     "Error: 'file' object has no attribute 'find'"
> >>>>
> >>>> Then I might be able to help, but I'm not sure how to
> >>>> reproduce it.  If
> >>>> you send a log file and config for this latter error I'll
> >>>> take a look.
> >>>> Yang seems to be reporting the same thing in another thread.
> >>>>
> >>>> --Dutch
> >>>>
> >>>> On Mon, 1 Jun 2009, Dan Magenheimer wrote:
> >>>>
> >>>>> Hmmm... trying blktap2 for the first time, using 19682.
> >>>>> I had thought that the syntax hadn't changed, but I am
> >>>>> getting what appears to be a parsing error on my vbd line.
> >>>>>
> >>>>> "ValueError: need more than 3 values to unpack"
> >>>>>
> >>>>> Thinking maybe that "w!" was the culprit, I changed
> >>>>> it to "w" with no change in result.
> >>>>>
> >>>>> Looking at the python code that generated the error,
> >>>>> I tried to figure out the syntax by experimentation
> >>>>> but without luck.  I tried:
> >>>>>
> >>>>> tap:tapdisk:aio:/pathto/file.img
> >>>>>
> >>>>> but got "Error: 'file' object has no attribute 'find'"
> >>>>>
> >>>>> To see if I could use the old blktap, I tried
> >>>>>
> >>>>> tap:tapdisk:ioemu:/pathto/file.img
> >>>>>
> >>>>> but got the dreaded "Error: Device 768 (tap) could not be
> >>>>> connected. Hotplug scripts not working"
> >>>>>
> >>>>> Am I missing something in the syntax for blktap2?
> >>>>> Is there a how-to or readme I didn't find?  Or
> >>>>> is there some required dependency I don't know about
> >>>>> that is missing?
> >>>>>
> >>>>> I thought maybe I had a bad install, so rebuilt and
> >>>>> reinstalled with the same result.
> >>>>>
> >>>>> xend.log and config file attached.
> >>>>>
> >>>>> Thanks,
> >>>>> Dan
> >>>>>
> >>>>> P.S. I am trying blktap2 because both blktap and
> >>>>> file-backed fail.  Blktap sometimes reads garbage
> >>>>> from the file and
> >>>>
> >>>> _______________________________________________
> >>>> Xen-devel mailing list
> >>>> Xen-devel@xxxxxxxxxxxxxxxxxxx
> >>>> http://lists.xensource.com/xen-devel
> >>>>
> >>
> >
>

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