Xen devel - Jun 2011 - Looking for xen-blkback patch for 2.6.39 kernel

Good morning,

I came across a post archived at LKML relating to a patch for the 2.6.39 kernel
bringing in xen-blkback driver. It was found here:
https://lkml.org/lkml/2011/5/12/532

I''m guessing there was an attachment made somewhere with a patch that I
can''t find on textual archives and was wondering if anyone could point
me in the right direction?

I have cloned the git tree but don''t see any blkback module or any
reference that would create it in the Makefiles... Have grepped through the
files and I can see reference to xen-blkfront but nothing for xen-blkback...

Maybe I''m missing something but as far as I can see that git tree has
nothing to allow support for the blkback driver.

Any help would be appreciated.

Iain
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On Fri, 2011-06-03 at 11:41 +0100, Iain Kay wrote:
> I came across a post archived at LKML relating to a patch for the
> 2.6.39 kernel bringing in xen-blkback driver. It was found here:
> https://lkml.org/lkml/2011/5/12/532
> 
> I''m guessing there was an attachment made somewhere with a patch
that
> I can''t find on textual archives and was wondering if anyone could
> point me in the right direction?
> 
> I have cloned the git tree but don''t see any blkback module or any
> reference that would create it in the Makefiles... Have grepped
> through the files and I can see reference to xen-blkfront but nothing
> for xen-blkback...
> 
> Maybe I''m missing something but as far as I can see that git tree
has
> nothing to allow support for the blkback driver.
Did you checkout the right branch (for-jens/xen-blkback-v3.2 in that
mail, there may be a newer one in the tree now though). A simple clone
will give you the default branch (probably named "master") which may
not
necessarily have what you want merged into it.

Ian.



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Ian,

Cheers for asking it forced me to re-look at git and I discovered a command to
list all the branches. Have since checked out
''remotes/origin/stable/xen-blkback-v3.3'' and seems to be doing
the trick.

This however contains the whole kernel rather than just a patch against 2.6.39.
I had envisaged the patch being a .patch file applied with the linux patch
utility but maybe I''m thinking of it all wrong. Would I be obtaining a
.patch file or would it be using git to create patches for use against kernel
upstream source?


Iain

On 3 Jun 2011, at 11:48, Ian Campbell wrote:
> On Fri, 2011-06-03 at 11:41 +0100, Iain Kay wrote:
>> I came across a post archived at LKML relating to a patch for the
>> 2.6.39 kernel bringing in xen-blkback driver. It was found here:
>> https://lkml.org/lkml/2011/5/12/532
>> 
>> I''m guessing there was an attachment made somewhere with a
patch that
>> I can''t find on textual archives and was wondering if anyone
could
>> point me in the right direction?
>> 
>> I have cloned the git tree but don''t see any blkback module or
any
>> reference that would create it in the Makefiles... Have grepped
>> through the files and I can see reference to xen-blkfront but nothing
>> for xen-blkback...
>> 
>> Maybe I''m missing something but as far as I can see that git
tree has
>> nothing to allow support for the blkback driver.
> 
> Did you checkout the right branch (for-jens/xen-blkback-v3.2 in that
> mail, there may be a newer one in the tree now though). A simple clone
> will give you the default branch (probably named "master") which
may not
> necessarily have what you want merged into it.
> 
> Ian.
> 
> 

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On Fri, Jun 03, 2011 at 12:05:09PM +0100, Iain Kay
wrote:
> Ian,
> 
> Cheers for asking it forced me to re-look at git and I discovered a command
to list all the branches. Have since checked out
''remotes/origin/stable/xen-blkback-v3.3'' and seems to be doing
the trick.
> 
> This however contains the whole kernel rather than just a patch against
2.6.39. I had envisaged the patch being a .patch file applied with the linux
patch utility but maybe I''m thinking of it all wrong. Would I be
obtaining a .patch file or would it be using git to create patches for use
against kernel upstream source?
> 
Btw did you realize xen-blkback is already merged to upstream Linux v3.0-rc1 ?

-- Pasi
> 
> Iain
> 
> On 3 Jun 2011, at 11:48, Ian Campbell wrote:
> 
> > On Fri, 2011-06-03 at 11:41 +0100, Iain Kay wrote:
> >> I came across a post archived at LKML relating to a patch for the
> >> 2.6.39 kernel bringing in xen-blkback driver. It was found here:
> >> https://lkml.org/lkml/2011/5/12/532
> >> 
> >> I''m guessing there was an attachment made somewhere with
a patch that
> >> I can''t find on textual archives and was wondering if
anyone could
> >> point me in the right direction?
> >> 
> >> I have cloned the git tree but don''t see any blkback
module or any
> >> reference that would create it in the Makefiles... Have grepped
> >> through the files and I can see reference to xen-blkfront but
nothing
> >> for xen-blkback...
> >> 
> >> Maybe I''m missing something but as far as I can see that
git tree has
> >> nothing to allow support for the blkback driver.
> > 
> > Did you checkout the right branch (for-jens/xen-blkback-v3.2 in that
> > mail, there may be a newer one in the tree now though). A simple clone
> > will give you the default branch (probably named "master")
which may not
> > necessarily have what you want merged into it.
> > 
> > Ian.
> > 
> > 
> 
> 
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xensource.com
> http://lists.xensource.com/xen-devel
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Please don''t top post.
http://wiki.xen.org/xenwiki/AskingXenDevelQuestions

On Fri, 2011-06-03 at 12:05 +0100, Iain Kay wrote:
> Ian,
> 
> Cheers for asking it forced me to re-look at git and I discovered a
> command to list all the branches. Have since checked out
> ''remotes/origin/stable/xen-blkback-v3.3'' and seems to be
doing the
> trick.
> 
> This however contains the whole kernel rather than just a patch
> against 2.6.39. I had envisaged the patch being a .patch file applied
> with the linux patch utility but maybe I''m thinking of it all
wrong.
> Would I be obtaining a .patch file or would it be using git to create
> patches for use against kernel upstream source?
git is a VCS so you can generate diffs from it, or extract individual
changesets etc. I suggest you google up the "git diff", "git
log" and
"git show" commands.

Ian.



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> Btw did you realize xen-blkback is already merged to upstream Linux
v3.0-rc1 ?
> 
> -- Pasi
I was not aware no. I hadn''t really considered it to be honest. My
thoughts where that 2.6.39 is here and ''stable'' whereas the
3.0 is an entire new major revision and is likely to introduce a less stable
experience.

Would I be wrong in thinking that?

Iain

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On 3 Jun 2011, at 13:02, Ian Campbell wrote:
> git is a VCS so you can generate diffs from it, or extract individual
> changesets etc. I suggest you google up the "git diff", "git
log" and
> "git show" commands.
> 
> Ian.
I was aware it is a VCS however have never attempted to create diff''s
with it. Will look into it.

Thanks.

Iain
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> Btw did you realize xen-blkback is already merged to upstream Linux
v3.0-rc1 ?
> 
> -- Pasi
I was not aware no. I hadn''t really considered it to be honest. My
thoughts where that 2.6.39 is here and ''stable'' whereas the
3.0 is an entire new major revision and is likely to introduce a less stable
experience.

Would I be wrong in thinking that?

Iain
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On Fri, 2011-06-03 at 15:12 +0100, Iain Kay wrote:
> > Btw did you realize xen-blkback is already merged to upstream Linux
v3.0-rc1 ?
> > 
> > -- Pasi
> 
> I was not aware no. I hadn''t really considered it to be honest. My
> thoughts where that 2.6.39 is here and ''stable'' whereas
the 3.0 is an
> entire new major revision and is likely to introduce a less stable
> experience.
> 
> Would I be wrong in thinking that?
3.0 is purely about renumbering, it is not a major release in the sense
that there is any major difference in the development cycle, code etc.
It won''t be any different to the 2.6.39,38,etc development cycles.

When 3.0 comes out you should consider switching to it to be exactly as
risky as switching to 2.6.40 would have been and you should consider the
3.0-rc releases the same as you would have treated 2.6.40-rc.

Ian.



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On Fri, Jun 03, 2011 at 03:12:24PM +0100, Iain Kay
wrote:
> > Btw did you realize xen-blkback is already merged to upstream Linux
v3.0-rc1 ?
> > 
> > -- Pasi
> 
> I was not aware no. I hadn''t really considered it to be honest. My
thoughts where that 2.6.39 is here and ''stable'' whereas the
3.0 is an entire new major revision and is likely to introduce a less stable
experience.
If you just want the patchset of xen-blkback against 2.6.39, go get the this
branch

stable/xen-blkback-v3.3

from: git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen.git

thought you will also need to extra patches on top, which are in in
stable/backend.base.v3
to compile.

Or you can just get the 2.6.39 stable tree that has those patches and some more
from

stable/2.6.39.x


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On 3 Jun 2011, at 16:46, Konrad Rzeszutek Wilk wrote:
> Or you can just get the 2.6.39 stable tree that has those patches and some
more from
> 
> stable/2.6.39.x
> 
I have attempted to compile this stable/2.6.39.x branch however running into
difficulties. The error I receive during make is:

 MODPOST vmlinux.o
 GEN     .version
 CHK     include/generated/compile.h
 UPD     include/generated/compile.h
 CC      init/version.o
 LD      init/built-in.o
 LD      .tmp_vmlinux1
mm/built-in.o: In function `enable_swap_info'':
/usr/local/src/stable/2.6.39.x/mm/swapfile.c:1566: undefined reference to
`frontswap_init''
make: *** [.tmp_vmlinux1] Error 1

Iain
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> From: Iain Kay [mailto:spam@iainkay.com]
> Sent: Friday, June 03, 2011 11:51 AM
> To: xen-devel@lists.xensource.com
> Subject: Re: [Xen-devel] Looking for xen-blkback patch for 2.6.39
> kernel
> 
> On 3 Jun 2011, at 16:46, Konrad Rzeszutek Wilk wrote:
> 
> > Or you can just get the 2.6.39 stable tree that has those patches and
> some more from
> >
> > stable/2.6.39.x
> >
> 
> I have attempted to compile this stable/2.6.39.x branch however running
> into difficulties. The error I receive during make is:
> 
>  MODPOST vmlinux.o
>  GEN     .version
>  CHK     include/generated/compile.h
>  UPD     include/generated/compile.h
>  CC      init/version.o
>  LD      init/built-in.o
>  LD      .tmp_vmlinux1
> mm/built-in.o: In function `enable_swap_info'':
> /usr/local/src/stable/2.6.39.x/mm/swapfile.c:1566: undefined reference
> to `frontswap_init''
> make: *** [.tmp_vmlinux1] Error 1
Sorry, that''s my bug.  I pointed Konrad to a git tree
which included frontswap but it was accidentally a stale
tree.  There is another commit to fix it but I don''t
think Konrad has had a chance to pull the fix yet
into his tree.

A quick workaround is to enable CONFIG_FRONTSWAP.... it
doesn''t do anything without being enabled at runtime so
will have no effect unless you know how to enable it.

Or you can manully pull this commit from my tree:
http://git.kernel.org/?p=linux/kernel/git/djm/tmem.git;a=commit;h=4cc8924f141157c39e1b2c113b2bf6f95a10f741

Dan

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On 3 Jun 2011, at 20:46, Dan Magenheimer wrote:
> 
> A quick workaround is to enable CONFIG_FRONTSWAP.... it
> doesn''t do anything without being enabled at runtime so
> will have no effect unless you know how to enable it.
> 
> Or you can manully pull this commit from my tree:
>
http://git.kernel.org/?p=linux/kernel/git/djm/tmem.git;a=commit;h=4cc8924f141157c39e1b2c113b2bf6f95a10f741
> 
> Dan
Cheers Dan. That''s done the trick.


Iain
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