Debian Bug report logs - #586772
blktap2 does not work

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Message #5 received at submit@bugs.debian.org (full text, mbox, reply):

From: Niccolò Belli <darkbasic4@gmail.com>

To: submit@bugs.debian.org

Subject: blktap2 does not work

Date: Tue, 22 Jun 2010 14:30:21 +0200

Package: xen-utils-4.0
Version: 4.0.0-2
Severity: normal

This is the config:
#HVM
#still no qemu-dm

#kernel = "/usr/lib/xen-4.0/boot/hvmloader"
#builder = 'hvm'
#memory = 2048
#name = "webserver"
#vif = ['bridge=eth0']
#disk = ['tap:tapdisk:aio:/srv/xen/webserver.img,xvda,w','phy:/dev/cdrom,xvdb:cdrom,r']
#device-model = '/usr/lib/xen-4.0/bin/qemu-dm'
#vnc = 1
#boot = 'd'


#PV

name = "webserver"
memory = 2048
bootloader = "/usr/lib/xen-4.0/bin/pygrub"
vif = ['bridge=eth0']
disk = [ "tap:tapdisk:aio:/srv/xen/webserver.img,xvda,w" ]
vnc = 1

When I run xm create /srv/xen/profiles/webserver.cfg I get:
Using config file "/srv/xen/profiles/webserver.cfg".
Error: [Errno 2] No such file or directory: 'aio:/srv/xen/webserver.img'

I created the image with dd:
# dd if=/dev/zero of=/srv/xen/webserver.img oflag=direct bs=1M seek=4095 count=1
# dd if=/dev/zero of=/srv/xen/webserver.img oflag=direct bs=1M count=4096

Darkbasic

Message #10 received at 586772@bugs.debian.org (full text, mbox, reply):

From: Niccolò Belli <darkbasic4@gmail.com>

To: 586772@bugs.debian.org

Subject: Re: [Pkg-xen-devel] Bug#586772: blktap2 does not work

Date: Wed, 23 Jun 2010 00:11:29 +0200

It seems blktap2 is not available in debian package. Please close.

Darkbasic

Message #15 received at 586772@bugs.debian.org (full text, mbox, reply):

From: Keith Russell <keith@qnx.com>

To: Debian Bug Tracking System <586772@bugs.debian.org>

Subject: xen-utils-4.0: No block tap backends available

Date: Wed, 20 Oct 2010 15:26:11 -0400

Package: xen-utils-4.0
Version: 4.0.1-1
Severity: normal

Due to license issues this version of Xen does not include the blktap2 backend (tapdisk2) and associated utilities (vhd-util, etc.). The decision was made to disable the blktap v1 kernel module (the default is now blktap2). As a result we can't use any tap devices which means worse performance than previousl. Since blktap1 was available in lenny this could be looked on as a regression.

Please consider either adding blktap2 or reinstating the blktap1 kernel module.

-- System Information:
Debian Release: squeeze/sid
  APT prefers testing
  APT policy: (500, 'testing')
Architecture: i386 (i686)

Kernel: Linux 2.6.32-5-xen-686 (SMP w/2 CPU cores)
Locale: LANG=en_CA.UTF-8, LC_CTYPE=en_CA.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash

Versions of packages xen-utils-4.0 depends on:
ii  e2fslibs                1.41.12-2        ext2/ext3/ext4 file system librari
ii  iproute                 20100519-3       networking and traffic control too
ii  libc6                   2.11.2-6         Embedded GNU C Library: Shared lib
ii  libncurses5             5.7+20100313-4   shared libraries for terminal hand
ii  libxenstore3.0          4.0.1-1          Xenstore communications library fo
ii  python-support          1.0.10           automated rebuilding support for P
ii  python2.5               2.5.5-8          An interactive high-level object-o
ii  udev                    163-1            /dev/ and hotplug management daemo
ii  xen-utils-common        4.0.0-1          XEN administrative tools - common 
ii  zlib1g                  1:1.2.3.4.dfsg-3 compression library - runtime

Versions of packages xen-utils-4.0 recommends:
ii  bridge-utils                  1.4-5      Utilities for configuring the Linu
ii  libc6-xen                     2.11.2-6   Embedded GNU C Library: Shared lib
ii  xen-hypervisor-4.0-i386 [xen- 4.0.1-1    The Xen Hypervisor on i386

Versions of packages xen-utils-4.0 suggests:
pn  xen-docs-4.0                  <none>     (no description available)

-- no debconf information

Message #20 received at 586772@bugs.debian.org (full text, mbox, reply):

From: Pasi Kärkkäinen <pasik@iki.fi>

To: Keith Russell <keith@qnx.com>, 586772@bugs.debian.org

Subject: Re: [Pkg-xen-devel] Bug#586772: xen-utils-4.0: No block tap backends available

Date: Wed, 20 Oct 2010 22:47:19 +0300

On Wed, Oct 20, 2010 at 03:26:11PM -0400, Keith Russell wrote:
> Package: xen-utils-4.0
> Version: 4.0.1-1
> Severity: normal
> 
> Due to license issues this version of Xen does not include the blktap2 backend (tapdisk2) and associated utilities (vhd-util, etc.). The decision was made to disable the blktap v1 kernel module (the default is now blktap2). As a result we can't use any tap devices which means worse performance than previousl. Since blktap1 was available in lenny this could be looked on as a regression.
> 
> Please consider either adding blktap2 or reinstating the blktap1 kernel module.
> 

I thought there was no real licensing issue. I recall some patches on xen-devel about that.

-- Pasi


> -- System Information:
> Debian Release: squeeze/sid
>   APT prefers testing
>   APT policy: (500, 'testing')
> Architecture: i386 (i686)
> 
> Kernel: Linux 2.6.32-5-xen-686 (SMP w/2 CPU cores)
> Locale: LANG=en_CA.UTF-8, LC_CTYPE=en_CA.UTF-8 (charmap=UTF-8)
> Shell: /bin/sh linked to /bin/dash
> 
> Versions of packages xen-utils-4.0 depends on:
> ii  e2fslibs                1.41.12-2        ext2/ext3/ext4 file system librari
> ii  iproute                 20100519-3       networking and traffic control too
> ii  libc6                   2.11.2-6         Embedded GNU C Library: Shared lib
> ii  libncurses5             5.7+20100313-4   shared libraries for terminal hand
> ii  libxenstore3.0          4.0.1-1          Xenstore communications library fo
> ii  python-support          1.0.10           automated rebuilding support for P
> ii  python2.5               2.5.5-8          An interactive high-level object-o
> ii  udev                    163-1            /dev/ and hotplug management daemo
> ii  xen-utils-common        4.0.0-1          XEN administrative tools - common 
> ii  zlib1g                  1:1.2.3.4.dfsg-3 compression library - runtime
> 
> Versions of packages xen-utils-4.0 recommends:
> ii  bridge-utils                  1.4-5      Utilities for configuring the Linu
> ii  libc6-xen                     2.11.2-6   Embedded GNU C Library: Shared lib
> ii  xen-hypervisor-4.0-i386 [xen- 4.0.1-1    The Xen Hypervisor on i386
> 
> Versions of packages xen-utils-4.0 suggests:
> pn  xen-docs-4.0                  <none>     (no description available)
> 
> -- no debconf information
> 
> 
> 
> _______________________________________________
> Pkg-xen-devel mailing list
> Pkg-xen-devel@lists.alioth.debian.org
> http://lists.alioth.debian.org/mailman/listinfo/pkg-xen-devel

Message #25 received at 586772@bugs.debian.org (full text, mbox, reply):

From: Ian Campbell <ijc@hellion.org.uk>

To: Pasi Kärkkäinen <pasik@iki.fi>, 586772@bugs.debian.org

Cc: Keith Russell <keith@qnx.com>

Subject: Re: [Pkg-xen-devel] Bug#586772: Bug#586772: xen-utils-4.0: No block tap backends available

Date: Thu, 21 Oct 2010 06:55:02 +0100

[Message part 1 (text/plain, inline)]

On Wed, 2010-10-20 at 22:47 +0300, Pasi Kärkkäinen wrote: 
> On Wed, Oct 20, 2010 at 03:26:11PM -0400, Keith Russell wrote:
> > Package: xen-utils-4.0
> > Version: 4.0.1-1
> > Severity: normal
> > 
> > Due to license issues this version of Xen does not include the blktap2 backend (tapdisk2) and associated utilities (vhd-util, etc.). The decision was made to disable the blktap v1 kernel module (the default is now blktap2). As a result we can't use any tap devices which means worse performance than previousl. Since blktap1 was available in lenny this could be looked on as a regression.
> > 
> > Please consider either adding blktap2 or reinstating the blktap1 kernel module.
> > 
> 
> I thought there was no real licensing issue. I recall some patches on xen-devel about that.

It was resolved in xen-unstable.hg 21547:ca2738f258 I think it would be
trivial to backport.

> 
> -- Pasi
> 
> 
> > -- System Information:
> > Debian Release: squeeze/sid
> >   APT prefers testing
> >   APT policy: (500, 'testing')
> > Architecture: i386 (i686)
> > 
> > Kernel: Linux 2.6.32-5-xen-686 (SMP w/2 CPU cores)
> > Locale: LANG=en_CA.UTF-8, LC_CTYPE=en_CA.UTF-8 (charmap=UTF-8)
> > Shell: /bin/sh linked to /bin/dash
> > 
> > Versions of packages xen-utils-4.0 depends on:
> > ii  e2fslibs                1.41.12-2        ext2/ext3/ext4 file system librari
> > ii  iproute                 20100519-3       networking and traffic control too
> > ii  libc6                   2.11.2-6         Embedded GNU C Library: Shared lib
> > ii  libncurses5             5.7+20100313-4   shared libraries for terminal hand
> > ii  libxenstore3.0          4.0.1-1          Xenstore communications library fo
> > ii  python-support          1.0.10           automated rebuilding support for P
> > ii  python2.5               2.5.5-8          An interactive high-level object-o
> > ii  udev                    163-1            /dev/ and hotplug management daemo
> > ii  xen-utils-common        4.0.0-1          XEN administrative tools - common 
> > ii  zlib1g                  1:1.2.3.4.dfsg-3 compression library - runtime
> > 
> > Versions of packages xen-utils-4.0 recommends:
> > ii  bridge-utils                  1.4-5      Utilities for configuring the Linu
> > ii  libc6-xen                     2.11.2-6   Embedded GNU C Library: Shared lib
> > ii  xen-hypervisor-4.0-i386 [xen- 4.0.1-1    The Xen Hypervisor on i386
> > 
> > Versions of packages xen-utils-4.0 suggests:
> > pn  xen-docs-4.0                  <none>     (no description available)
> > 
> > -- no debconf information
> > 
> > 
> > 
> > _______________________________________________
> > Pkg-xen-devel mailing list
> > Pkg-xen-devel@lists.alioth.debian.org
> > http://lists.alioth.debian.org/mailman/listinfo/pkg-xen-devel
> 
> 
> 
> _______________________________________________
> Pkg-xen-devel mailing list
> Pkg-xen-devel@lists.alioth.debian.org
> http://lists.alioth.debian.org/mailman/listinfo/pkg-xen-devel
> 

-- 
Ian Campbell

A man always remembers his first love with special tenderness, but after
that begins to bunch them.
		-- Mencken

[signature.asc (application/pgp-signature, inline)]

Message #30 received at 586772@bugs.debian.org (full text, mbox, reply):

From: Łukasz Oleś <lukaszoles@gmail.com>

To: pkg-xen-devel@lists.alioth.debian.org, waldi@debian.org, 586772@bugs.debian.org

Subject: [patch] blktap2 support

Date: Mon, 27 Dec 2010 20:52:23 +0100

[Message part 1 (text/plain, inline)]

Hello,

this two patches add blktap2 functionality to xen-utils. I backported
http://xenbits.xen.org/xen-unstable.hg?rev/ca2738f258f8 to remove
license issues.

First patch(xen-common.patch) is for xen-utils-common, second
patch(xen-utils.patch) is for xen-utils. To apply it just enter to
'debian' dir and run `patch -p2 <patch_name`

Regards,

-- 
Łukasz Oleś

[xen-common.patch (text/x-patch, attachment)]

[xen-utils.patch (text/x-patch, attachment)]

Message #35 received at 586772@bugs.debian.org (full text, mbox, reply):

From: Niccolò Belli <darkbasic4@gmail.com>

To: 586772@bugs.debian.org

Subject: RE: blktap2 does not work

Date: Tue, 25 Jan 2011 10:07:42 +0100

> this two patches add blktap2 functionality to xen-utils. I backported
> http://xenbits.xen.org/xen-unstable.hg?rev/ca2738f258f8 to remove
> license issues.

Has this patch been applied?

Darkbasic

Message #40 received at 586772@bugs.debian.org (full text, mbox, reply):

From: Gedalya <gedalya@thejnet.com>

To: 586772@bugs.debian.org

Subject: RE: blktap2 does not work

Date: Wed, 26 Jan 2011 14:56:15 -0500

I tried the patch from Łukasz Oleś, I had trouble building a debian 
package built including the tools (maybe I'm doing something wrong?) but 
I can confirm the patch itself works flawlessly (squeeze, amd64) without 
a need for openssl, I just had to manually install the blktap2 tools.

Please, can this patch be committed? This is a very important feature 
for certain scenarios. It would be extremely helpful.

Thanks,

Gedalya

Message #45 received at 586772@bugs.debian.org (full text, mbox, reply):

From: Niccolò Belli <darkbasic4@gmail.com>

To: Gedalya <gedalya@thejnet.com>, 586772@bugs.debian.org

Subject: Re: [Pkg-xen-devel] Bug#586772: blktap2 does not work

Date: Wed, 26 Jan 2011 21:21:58 +0100

Il 26/01/2011 20:56, Gedalya ha scritto:
> Please, can this patch be committed? This is a very important feature
> for certain scenarios. It would be extremely helpful.

Tons of users already asked it months ago :(

Darkbasic

Message #50 received at 586772@bugs.debian.org (full text, mbox, reply):

From: Josef <pepus@p-h-a.cz>

To: 586772@bugs.debian.org

Subject: any progress?

Date: Tue, 08 Mar 2011 00:35:00 +0100

 Could someone commit the patch? Absence of a block device forces users 
to use a slow and not-suggested file storage.

Message #55 received at 586772@bugs.debian.org (full text, mbox, reply):

From: jesse <thoughtafter@gmail.com>

To: 586772@bugs.debian.org

Subject: ran into this today

Date: Thu, 10 Mar 2011 11:21:17 -0800

This is a serious regression from Lenny which will prevent any of my
production systems from being able to upgrade.  On my test system it
seems that blktap is broken, blktap2 is missing, only file works, which,
as noted here, is not recommended.  This is perhaps more of a kernel bug
than a xen bug so I'm not sure if this bug should be linked to the
kernel package.

Message #60 received at 586772@bugs.debian.org (full text, mbox, reply):

From: Jayson Vantuyl <jayson@gogrid.com>

To: "586772@bugs.debian.org" <586772@bugs.debian.org>

Subject: blktap2 Support

Date: Wed, 7 Mar 2012 17:04:18 -0800

[Message part 1 (text/plain, inline)]

We have a great many VMs that are stuck on Lenny because of this.  Probably can build it ourselves, but would prefer to avoid the maintenance nightmare.  Please make this happen, as we really like Debian.

Thanks,


--
Jayson Vantuyl
jayson@gogrid.com<mailto:jayson@gogrid.com>
417-207-6962<tel:+14172076962> (mobile)


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Message #65 received at 586772@bugs.debian.org (full text, mbox, reply):

From: Niccolò Belli <darkbasic4@gmail.com>

To: Jayson Vantuyl <jayson@gogrid.com>, 586772@bugs.debian.org

Subject: Re: [Pkg-xen-devel] Bug#586772: blktap2 Support

Date: Thu, 08 Mar 2012 11:19:58 +0100

Forget about blktap2 in Squeeze... Unfortunately it doesn't work even 
backporting 4.1.2-3.

Niccolò

Message #70 received at 586772@bugs.debian.org (full text, mbox, reply):

From: Ian Campbell <ijc@hellion.org.uk>

To: Niccolò Belli <darkbasic4@gmail.com>, 586772@bugs.debian.org

Cc: Jayson Vantuyl <jayson@gogrid.com>

Subject: Re: [Pkg-xen-devel] Bug#586772: Bug#586772: blktap2 Support

Date: Thu, 08 Mar 2012 08:44:58 -0800

On Thu, 2012-03-08 at 11:19 +0100, Niccolò Belli wrote:
> Forget about blktap2 in Squeeze... Unfortunately it doesn't work even 
> backporting 4.1.2-3.

There is no kernel side in Squeeze so backporting the userspace side
will not work.

You could try backporting the blktap-dkms stuff from Sid/Wheezy along
with the associated blktap-utils. They were included for use with the
xapi toolstack but they might also work with others.

Long term upstream is working on a version of blktap with no requirement
for a kernel driver.

Ian.

-- 
Ian Campbell

Conscience is what hurts when everything else feels so good.

Message #75 received at 586772@bugs.debian.org (full text, mbox, reply):

From: Niccolò Belli <darkbasic4@gmail.com>

To: Ian Campbell <ijc@hellion.org.uk>

Cc: 586772@bugs.debian.org, Jayson Vantuyl <jayson@gogrid.com>

Subject: Re: [Pkg-xen-devel] Bug#586772: Bug#586772: blktap2 Support

Date: Thu, 8 Mar 2012 18:44:05 +0100

Uh? Really? I'm pretty sure blktap2 did work with upstream
xen-4.0-rc$something (not the debian packages) and the official
(pre-)Squeeze 2.6.32 xen kernel.

On Thu, Mar 8, 2012 at 5:44 PM, Ian Campbell <ijc@hellion.org.uk> wrote:
> There is no kernel side in Squeeze so backporting the userspace side
> will not work.

Message #80 received at 586772@bugs.debian.org (full text, mbox, reply):

From: Ian Campbell <ijc@hellion.org.uk>

To: Niccolò Belli <darkbasic4@gmail.com>

Cc: 586772@bugs.debian.org, Jayson Vantuyl <jayson@gogrid.com>

Subject: Re: [Pkg-xen-devel] Bug#586772: Bug#586772: blktap2 Support

Date: Thu, 08 Mar 2012 09:47:48 -0800

On Thu, 2012-03-08 at 18:44 +0100, Niccolò Belli wrote:
> Uh? Really? I'm pretty sure blktap2 did work with upstream
> xen-4.0-rc$something (not the debian packages) and the official
> (pre-)Squeeze 2.6.32 xen kernel.

Hmm. Perhaps I'm confused then.

There was a breakage of the blktap userspace <-> kernel ABI at one
point, which might stop 4.1 working with 2.6.32 era kernel wihch might
also explain this.

In any case trying the DKMS ting and matching blktap binaries is
worthwhile because it might work.

Ian.
-- 
Ian Campbell

Are we running light with overbyte?

Message #85 received at 586772@bugs.debian.org (full text, mbox, reply):

From: Niccolò Belli <darkbasic4@gmail.com>

To: Ian Campbell <ijc@hellion.org.uk>

Cc: 586772@bugs.debian.org, Jayson Vantuyl <jayson@gogrid.com>

Subject: Re: [Pkg-xen-devel] Bug#586772: Bug#586772: blktap2 Support

Date: Thu, 08 Mar 2012 21:03:52 +0100

Il 08/03/2012 18:47, Ian Campbell ha scritto:
> There was a breakage of the blktap userspace<->  kernel ABI at one
> point, which might stop 4.1 working with 2.6.32 era kernel wihch might
> also explain this.

That may be the problem indeed, the only reason Squeeze didn't get 
blktap2 was a stupid license issue (stupid because it has been solved 
but no one cared reverting the "disable blktap2" commit in debian).

Unfortunately I don't think backporting blktap-dkms will be an easy task:

DKMS make.log for blktap-2.0.91 for kernel 2.6.32-5-xen-amd64 (x86_64)
gio  8 mar 2012, 19.48.20, CET
make: Entering directory `/usr/src/linux-headers-2.6.32-5-xen-amd64'
  CC [M]  /var/lib/dkms/blktap/2.0.91/build/control.o
  CC [M]  /var/lib/dkms/blktap/2.0.91/build/ring.o
  CC [M]  /var/lib/dkms/blktap/2.0.91/build/device.o
/var/lib/dkms/blktap/2.0.91/build/device.c: In function 
‘blktap_device_make_request’:
/var/lib/dkms/blktap/2.0.91/build/device.c:212: error: ‘REQ_FLUSH’ 
undeclared (first use in this function)
/var/lib/dkms/blktap/2.0.91/build/device.c:212: error: (Each undeclared 
identifier is reported only once
/var/lib/dkms/blktap/2.0.91/build/device.c:212: error: for each function 
it appears in.)
/var/lib/dkms/blktap/2.0.91/build/device.c: In function 
‘blktap_device_configure’:
/var/lib/dkms/blktap/2.0.91/build/device.c:337: error: implicit 
declaration of function ‘blk_queue_max_segments’
/var/lib/dkms/blktap/2.0.91/build/device.c:345: error: implicit 
declaration of function ‘blk_queue_flush’
/var/lib/dkms/blktap/2.0.91/build/device.c:345: error: ‘REQ_FLUSH’ 
undeclared (first use in this function)
/var/lib/dkms/blktap/2.0.91/build/device.c:353: error: ‘struct 
queue_limits’ has no member named ‘discard_granularity’
/var/lib/dkms/blktap/2.0.91/build/device.c:354: error: ‘struct 
queue_limits’ has no member named ‘discard_alignment’
/var/lib/dkms/blktap/2.0.91/build/device.c:355: error: ‘struct 
queue_limits’ has no member named ‘discard_zeroes_data’
/var/lib/dkms/blktap/2.0.91/build/device.c: In function 
‘blktap_device_create’:
/var/lib/dkms/blktap/2.0.91/build/device.c:562: error: ‘struct 
queue_limits’ has no member named ‘discard_granularity’
/var/lib/dkms/blktap/2.0.91/build/device.c:562: error: implicit 
declaration of function ‘queue_discard_alignment’
/var/lib/dkms/blktap/2.0.91/build/device.c:562: error: ‘struct 
request_queue’ has no member named ‘flush_flags’
make[3]: *** [/var/lib/dkms/blktap/2.0.91/build/device.o] Error 1
make[2]: *** [_module_/var/lib/dkms/blktap/2.0.91/build] Error 2
make[1]: *** [sub-make] Error 2
make: *** [all] Error 2
make: Leaving directory `/usr/src/linux-headers-2.6.32-5-xen-amd64'


Niccolò

Message #90 received at 586772@bugs.debian.org (full text, mbox, reply):

From: Thomas Goirand <thomas@goirand.fr>

To: Niccolò Belli <darkbasic4@gmail.com>, 586772@bugs.debian.org

Cc: Jayson Vantuyl <jayson@gogrid.com>

Subject: Re: [Pkg-xen-devel] Bug#586772: Bug#586772: Bug#586772: blktap2 Support

Date: Sat, 10 Mar 2012 01:56:47 +0800

On 03/09/2012 04:03 AM, Niccolò Belli wrote:
> Il 08/03/2012 18:47, Ian Campbell ha scritto:
>> There was a breakage of the blktap userspace<->  kernel ABI at one
>> point, which might stop 4.1 working with 2.6.32 era kernel wihch might
>> also explain this.
> 
> That may be the problem indeed, the only reason Squeeze didn't get
> blktap2 was a stupid license issue (stupid because it has been solved
> but no one cared reverting the "disable blktap2" commit in debian).
> 
> Unfortunately I don't think backporting blktap-dkms will be an easy task:
> 
> [... lots of errors ...]
> 
> Niccolò

Have you considered using the backported Linux 3.2 kernel? I don't see
why blktap-dkms would fail there.

Thomas

Message #95 received at 586772@bugs.debian.org (full text, mbox, reply):

From: Niccolò Belli <darkbasic4@gmail.com>

To: Thomas Goirand <thomas@goirand.fr>

Cc: 586772@bugs.debian.org, Jayson Vantuyl <jayson@gogrid.com>

Subject: Re: [Pkg-xen-devel] Bug#586772: Bug#586772: Bug#586772: blktap2 Support

Date: Fri, 09 Mar 2012 22:53:31 +0100

Il 09/03/2012 18:56, Thomas Goirand ha scritto:
> Have you considered using the backported Linux 3.2 kernel? I don't see
> why blktap-dkms would fail there.

I do apply 15 different patches and I wasted lots of time trying to get 
rid of the kernel panics and the tons of issues I had, switching to 
another kernel isn't an option.

Message #100 received at 586772@bugs.debian.org (full text, mbox, reply):

From: Ian Campbell <ijc@hellion.org.uk>

To: Niccolò Belli <darkbasic4@gmail.com>

Cc: 586772@bugs.debian.org, Jayson Vantuyl <jayson@gogrid.com>

Subject: Re: [Pkg-xen-devel] Bug#586772: Bug#586772: blktap2 Support

Date: Wed, 14 Mar 2012 13:34:21 +0000

On Thu, 2012-03-08 at 21:03 +0100, Niccolò Belli wrote:
> Il 08/03/2012 18:47, Ian Campbell ha scritto:
> > There was a breakage of the blktap userspace<->  kernel ABI at one
> > point, which might stop 4.1 working with 2.6.32 era kernel wihch might
> > also explain this.
> 
> That may be the problem indeed, the only reason Squeeze didn't get 
> blktap2 was a stupid license issue (stupid because it has been solved 
> but no one cared reverting the "disable blktap2" commit in debian).
> 
> Unfortunately I don't think backporting blktap-dkms will be an easy task:
> 
> DKMS make.log for blktap-2.0.91 for kernel 2.6.32-5-xen-amd64 (x86_64)
> gio  8 mar 2012, 19.48.20, CET
> make: Entering directory `/usr/src/linux-headers-2.6.32-5-xen-amd64'
>    CC [M]  /var/lib/dkms/blktap/2.0.91/build/control.o
>    CC [M]  /var/lib/dkms/blktap/2.0.91/build/ring.o
>    CC [M]  /var/lib/dkms/blktap/2.0.91/build/device.o
> /var/lib/dkms/blktap/2.0.91/build/device.c: In function 
> ‘blktap_device_make_request’:
> /var/lib/dkms/blktap/2.0.91/build/device.c:212: error: ‘REQ_FLUSH’ 
> undeclared (first use in this function)

Hrm, that's unfortunate.

I suspect it wouldn't be that hard for someone to add the necessary
compat #ifdefs etc to allow these modules to build on a variety of
kernels (e.g. a diff vs. the 2.6.32 branch from xen.git would give some
guidance).

Perhaps an alternative solution is to use the blktap driver from the
2.6.32 kernel package but revert 21707:feee0abed6aa from the userspace
side, I think (although I'm not 100% sure[0]) that this is the changeset
which caused the incompatibility.

FWIW the corresponding commit in the xen.git kernel tree seems to be
9ccc03593edcfb70ea846da414d5671952e7e831.

BTW, back in <4F5887CE.3050100@gmail.com> you said:
        Forget about blktap2 in Squeeze... Unfortunately it doesn't work
        even backporting 4.1.2-3.
I should have asked -- what exactly didn't work, what was the failure
mode? (I'm wondering if my thoughts about this compatibility issue I
mentioned above might have been jumping to a conclusion without
sufficient data?)

Ian.

[0] my memory of the particular issue I'm thinking of is very fuzzy.
I've had a look back over the xen-devel archives to see if it jogged my
memory, but no luck.


> /var/lib/dkms/blktap/2.0.91/build/device.c:212: error: (Each undeclared 
> identifier is reported only once
> /var/lib/dkms/blktap/2.0.91/build/device.c:212: error: for each function 
> it appears in.)
> /var/lib/dkms/blktap/2.0.91/build/device.c: In function 
> ‘blktap_device_configure’:
> /var/lib/dkms/blktap/2.0.91/build/device.c:337: error: implicit 
> declaration of function ‘blk_queue_max_segments’
> /var/lib/dkms/blktap/2.0.91/build/device.c:345: error: implicit 
> declaration of function ‘blk_queue_flush’
> /var/lib/dkms/blktap/2.0.91/build/device.c:345: error: ‘REQ_FLUSH’ 
> undeclared (first use in this function)
> /var/lib/dkms/blktap/2.0.91/build/device.c:353: error: ‘struct 
> queue_limits’ has no member named ‘discard_granularity’
> /var/lib/dkms/blktap/2.0.91/build/device.c:354: error: ‘struct 
> queue_limits’ has no member named ‘discard_alignment’
> /var/lib/dkms/blktap/2.0.91/build/device.c:355: error: ‘struct 
> queue_limits’ has no member named ‘discard_zeroes_data’
> /var/lib/dkms/blktap/2.0.91/build/device.c: In function 
> ‘blktap_device_create’:
> /var/lib/dkms/blktap/2.0.91/build/device.c:562: error: ‘struct 
> queue_limits’ has no member named ‘discard_granularity’
> /var/lib/dkms/blktap/2.0.91/build/device.c:562: error: implicit 
> declaration of function ‘queue_discard_alignment’
> /var/lib/dkms/blktap/2.0.91/build/device.c:562: error: ‘struct 
> request_queue’ has no member named ‘flush_flags’
> make[3]: *** [/var/lib/dkms/blktap/2.0.91/build/device.o] Error 1
> make[2]: *** [_module_/var/lib/dkms/blktap/2.0.91/build] Error 2
> make[1]: *** [sub-make] Error 2
> make: *** [all] Error 2
> make: Leaving directory `/usr/src/linux-headers-2.6.32-5-xen-amd64'
> 
> 
> Niccolò
> 

-- 
Ian Campbell

I prefer the most unjust peace to the most righteous war.
		-- Cicero

Even peace may be purchased at too high a price.
		-- Poor Richard

Message #105 received at 586772@bugs.debian.org (full text, mbox, reply):

From: Niccolò Belli <darkbasic4@gmail.com>

To: Ian Campbell <ijc@hellion.org.uk>

Cc: 586772@bugs.debian.org, Jayson Vantuyl <jayson@gogrid.com>

Subject: Re: [Pkg-xen-devel] Bug#586772: Bug#586772: blktap2 Support

Date: Wed, 14 Mar 2012 15:21:45 +0100

Il 14/03/2012 14:34, Ian Campbell ha scritto:
> I should have asked -- what exactly didn't work, what was the failure
> mode? (I'm wondering if my thoughts about this compatibility issue I
> mentioned above might have been jumping to a conclusion without
> sufficient data?)

As soon as you load the blktap module you will not be able to access the 
disks anymore. I don't remember of messages in the console (except when 
you are using pygrub: "failed to run bootloader: -3").
I tried both stacks: xm and xl.

Niccolò

Message #114 received at 586772-submitter@bugs.debian.org (full text, mbox, reply):

From: Ian Campbell <ijc@debian.org>

To: control@bugs.debian.org

Cc: 586772-submitter@bugs.debian.org

Subject: closing 586772

Date: Mon, 17 Nov 2014 19:21:00 +0000

close 586772 4.4.0-1
thanks

Unfortunately it seems that blktap2 is dead in the water upstream and the work
towards a userspace solution has stalled too, it's unclear what if anything is
going to happen there.

However in Xen 4.4.0 the qdisk PV backend (provided by qemu) provides a similar
solution and has become the default for all non-physical disk backends in libxl
based toolstacks. So I recommend switching to that (I expect it will happen
mostly automatically actually, i.e. xl/libxl will just do the right thing).

Ian.

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