Re: [Xen-devel] What is the state of blktap2?

["David P. Quigley" <dpquigl@xxxxxxxxxxxxx>]

On Fri, 2010-01-22 at 00:55 +0200, Pasi KÃrkkÃinen wrote:
> On Thu, Jan 21, 2010 at 05:46:05PM -0500, David P. Quigley wrote:
> > On Fri, 2010-01-22 at 00:38 +0200, Pasi KÃrkkÃinen wrote:
> > > On Thu, Jan 21, 2010 at 05:27:45PM -0500, David P. Quigley wrote:
> > > > I'm currently working on moving storage services into their own domain
> > > > and I've been looking at blktap2. I've been trying to get an image
> > > > mounted with blktap2 and for some odd reason and tapdisk2 keeps hanging
> > > > instead of quitting at the end. I haven't removed any of the storage
> > > > startup code at this point so everything should be as it normally is in
> > > > xen-unstable. Is this a known bug? Are there some requirements on
> > > > blktap2 that I'm possibly not meeting? Is there anything in particular
> > > > that I should be looking at to try to debug the problem?
> > > > 
> > > 
> > > What kernel are you using? pv_ops dom0 kernel doesn't have working 
> > > blktap2 yet..
> > > linux-2.6.18-xen has working blktap2 support.
> > > 
> > > -- Pasi
> > 
> > I'm using the patches maintained by Andrew Lyon that are applied to
> > 2.6.31.10. These are supposedly based on the OpenSUSE patches and can be
> > found at http://code.google.com/p/gentoo-xen-kernel/downloads/list. I
> > need a more recent kernel version so the 2.6.18 dom0 kernel isn't an
> > option for me.
> > 
> 
> Ok. I'm not sure if those OpenSUSE patches have blktap2 support included?
> I know that at least Citrix XenServer, XCP and XCI 2.6.27 kernels do have 
> blktap2.
> 
> See:
> http://wiki.xensource.com/xenwiki/XenDom0Kernels
> 
> -- Pasi


$ grep BLKTAP2 *
60011_xen3-auto-xen-drivers.patch1:+#define BLKTAP2_IOCTL_KICK_FE        1
60011_xen3-auto-xen-drivers.patch1:+#define BLKTAP2_IOCTL_ALLOC_TAP          200
60011_xen3-auto-xen-drivers.patch1:+#define BLKTAP2_IOCTL_FREE_TAP       201
60011_xen3-auto-xen-drivers.patch1:+#define BLKTAP2_IOCTL_CREATE_DEVICE  202
60011_xen3-auto-xen-drivers.patch1:+#define BLKTAP2_IOCTL_SET_PARAMS     203
60011_xen3-auto-xen-drivers.patch1:+#define BLKTAP2_IOCTL_PAUSE          204
60011_xen3-auto-xen-drivers.patch1:+#define BLKTAP2_IOCTL_REOPEN         205
60011_xen3-auto-xen-drivers.patch1:+#define BLKTAP2_IOCTL_RESUME         206
60011_xen3-auto-xen-drivers.patch1:+#define BLKTAP2_MAX_MESSAGE_LEN      256
60011_xen3-auto-xen-drivers.patch1:+#define BLKTAP2_RING_MESSAGE_PAUSE   1
60011_xen3-auto-xen-drivers.patch1:+#define BLKTAP2_RING_MESSAGE_RESUME  2
60011_xen3-auto-xen-drivers.patch1:+#define BLKTAP2_RING_MESSAGE_CLOSE   3
60011_xen3-auto-xen-drivers.patch1:+    char                           
name[BLKTAP2_MAX_MESSAGE_LEN];
60011_xen3-auto-xen-drivers.patch1:+    case BLKTAP2_IOCTL_ALLOC_TAP: {
60011_xen3-auto-xen-drivers.patch1:+    case BLKTAP2_IOCTL_FREE_TAP:
60011_xen3-auto-xen-drivers.patch1:+    case BLKTAP2_IOCTL_KICK_FE:
60011_xen3-auto-xen-drivers.patch1:+    case BLKTAP2_IOCTL_CREATE_DEVICE:
60011_xen3-auto-xen-drivers.patch1:+    case BLKTAP2_IOCTL_SET_PARAMS:
60011_xen3-auto-xen-drivers.patch1:+    case BLKTAP2_IOCTL_PAUSE:
60011_xen3-auto-xen-drivers.patch1:+    case BLKTAP2_IOCTL_REOPEN:
60011_xen3-auto-xen-drivers.patch1:+    case BLKTAP2_IOCTL_RESUME:
60011_xen3-auto-xen-drivers.patch1:+    blktap_ring_set_message(tap, 
BLKTAP2_RING_MESSAGE_RESUME);
60011_xen3-auto-xen-drivers.patch1:+    blktap_ring_set_message(tap, 
BLKTAP2_RING_MESSAGE_PAUSE);
60011_xen3-auto-xen-drivers.patch1:+    blktap_ring_set_message(tap, 
BLKTAP2_RING_MESSAGE_CLOSE);
60011_xen3-auto-xen-drivers.patch1:+    if (size > BLKTAP2_MAX_MESSAGE_LEN) {
60011_xen3-auto-xen-drivers.patch1:+    if (strnlen(buf, 
BLKTAP2_MAX_MESSAGE_LEN) >= BLKTAP2_MAX_MESSAGE_LEN) {

Based on that I think it has some level of blktap2 integration.
Unfortunately its not clear if it has it all and if so at what point the
code was taken from.


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