Re: [Xen-devel] [PATCH 0 of 4] aio event fd support to blktap2

[Daniel Stodden <daniel.stodden@xxxxxxxxxx>]

On Tue, 2010-02-02 at 18:23 -0500, David P. Quigley wrote:
> On Tue, 2010-02-02 at 15:10 -0800, Daniel Stodden wrote:
> > On Tue, 2010-02-02 at 17:53 -0500, David P. Quigley wrote:
> > > Is this patch set related to the AIO poll support that blocktap2 keeps
> > > complaining about when I use tap:tapdisk:aio as the disk type? 
> > 
> > On pvops, yes.
> > 
> > > I found
> > > the code that changes io_setup in the Novell Xen patches but its part of
> > > a reasonably large patch.
> > 
> > Shouldn't depend on the disktype. As long as it's blktap, not blkback on
> > a raw vdi, all disk drivers depend on this.
> > 
> > The io_setup change you're referring might rather be the old way of
> > doing things. It made io_setup return an fd to poll, if the io_setup
> > caller calls with a 'magic' (1, actually) aio_ctx value.
> > 
> > Daniel
> > 
> 
> Seems like I made a mistake and copied the version of the error that was
> generated before I updated xen-unstable to have your latest changes. Now
> I'm getting a completely different error. Does the aio driver handle raw
> disk files or do I need to create the image in some special way? Not the
> error I get has to do with incorrect magic in the shared info and this
> results in a segfault. I'll try to hunt them down. The tapdisk output is
> listed below.
> 
> Dave
> 
> tapdisk2[2366]: Created /dev/xen/blktap-2/blktap0 device
> tapdisk2[2366]: Created /dev/xen/blktap-2/tapdev0 device
> tapdisk2[2366]: new interface: ring: 251, device: 253, minor: 0
> tapdisk2[2366]: I/O queue driver: lio
> tapdisk2[2366]: Incorrect magic in shared info.
> tapdisk2[2366]: Failed to open shared info.
> tapdisk2[2366]: segfault at 18 ip 0000003e42008dc1 sp 00007fffd29889a0 error 
> 4 in libpthread-2.10.2.so[3e42000000+17000]

Please try disabling -DMEMSHR in the Makefile.

[Assuming that helps: Keir, I think there is help underway, but should
we turn it off by default in the meantime?]

Is this on the pvops kernel?

- Make sure it doesn't have HIGHPTE set.
- Apply the bunch of kernel patches posted. ("blktap2 on pvops updates")
  I don't think they made it into Jeremy's tree yet.

Let me know if there's more trouble, we're presently preparing another
bunch of updates, so the time is just right :)

Daniel


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