XEN 3.4 and blktapctrl

XEN 3.4 and blktapctrl

[VM-Sascha]

Hello all, 

i'm playing with the new XEN 3.4 and if i use the backend "tap:aio" on my
domUs, all have the same
tapctrlwriteX & tapctrlreadX fifos

<SNIP>

tapdisk /var/run/tap/tapctrlwrite312222 /var/run/tap/tapctrlread312222
tapdisk /var/run/tap/tapctrlwrite312222 /var/run/tap/tapctrlread312222
tapdisk /var/run/tap/tapctrlwrite312222 /var/run/tap/tapctrlread312222
tapdisk /var/run/tap/tapctrlwrite312222 /var/run/tap/tapctrlread312222

</SNIP>

On XEN 3.3.1 it was always the domid like this:

<SNIP>

tapdisk /var/run/tap/tapctrlwrite1 /var/run/tap/tapctrlread1
tapdisk /var/run/tap/tapctrlwrite2 /var/run/tap/tapctrlread2
tapdisk /var/run/tap/tapctrlwrite3 /var/run/tap/tapctrlread3
tapdisk /var/run/tap/tapctrlwrite4 /var/run/tap/tapctrlread4

</SNIP>

Has anyone an idea why this happens on the new release?

Thanks,
Sascha



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Re: XEN 3.4 and blktapctrl

[Keir Fraser]

I'll guess that Kevin Wolf's changeset 19349 causes this, by calling
connect_tapdisk() with uninitialised parameter 'minor'. If you build Xen 3.4
yourself you can try reverting this patch with 'hg export 19349 | patch
-Rp1' and rebuild the tools.

Kevin: could you take another look at your patch, please.

 -- Keir

On 29/05/2009 11:14, "VM-Sascha" <sascha@argc.de> wrote:

> 
> Hello all, 
> 
> i'm playing with the new XEN 3.4 and if i use the backend "tap:aio" on my
> domUs, all have the same
> tapctrlwriteX & tapctrlreadX fifos
> 
> <SNIP>
> 
> tapdisk /var/run/tap/tapctrlwrite312222 /var/run/tap/tapctrlread312222
> tapdisk /var/run/tap/tapctrlwrite312222 /var/run/tap/tapctrlread312222
> tapdisk /var/run/tap/tapctrlwrite312222 /var/run/tap/tapctrlread312222
> tapdisk /var/run/tap/tapctrlwrite312222 /var/run/tap/tapctrlread312222
> 
> </SNIP>
> 
> On XEN 3.3.1 it was always the domid like this:
> 
> <SNIP>
> 
> tapdisk /var/run/tap/tapctrlwrite1 /var/run/tap/tapctrlread1
> tapdisk /var/run/tap/tapctrlwrite2 /var/run/tap/tapctrlread2
> tapdisk /var/run/tap/tapctrlwrite3 /var/run/tap/tapctrlread3
> tapdisk /var/run/tap/tapctrlwrite4 /var/run/tap/tapctrlread4
> 
> </SNIP>
> 
> Has anyone an idea why this happens on the new release?
> 
> Thanks,
> Sascha
> 
> 

Re: XEN 3.4 and blktapctrl

[VM-Sascha]

Hi Keir, 

yes, that's the trick. Every tapctrl fifo gets now a own minor number. 
Now, the "tap:aio" is working as on XEN 3.3.1!

Thanks,
Sascha 



Keir Fraser-3 wrote:
> 
> I'll guess that Kevin Wolf's changeset 19349 causes this, by calling
> connect_tapdisk() with uninitialised parameter 'minor'. If you build Xen
> 3.4
> yourself you can try reverting this patch with 'hg export 19349 | patch
> -Rp1' and rebuild the tools.
> 
> Kevin: could you take another look at your patch, please.
> 
>  -- Keir
> 
> On 29/05/2009 11:14, "VM-Sascha" <sascha@XXXXXXXXX> wrote:
> 
>> 
>> Hello all, 
>> 
>> i'm playing with the new XEN 3.4 and if i use the backend "tap:aio" on my
>> domUs, all have the same
>> tapctrlwriteX & tapctrlreadX fifos
>> 
>> <SNIP>
>> 
>> tapdisk /var/run/tap/tapctrlwrite312222 /var/run/tap/tapctrlread312222
>> tapdisk /var/run/tap/tapctrlwrite312222 /var/run/tap/tapctrlread312222
>> tapdisk /var/run/tap/tapctrlwrite312222 /var/run/tap/tapctrlread312222
>> tapdisk /var/run/tap/tapctrlwrite312222 /var/run/tap/tapctrlread312222
>> 
>> </SNIP>
>> 
>> On XEN 3.3.1 it was always the domid like this:
>> 
>> <SNIP>
>> 
>> tapdisk /var/run/tap/tapctrlwrite1 /var/run/tap/tapctrlread1
>> tapdisk /var/run/tap/tapctrlwrite2 /var/run/tap/tapctrlread2
>> tapdisk /var/run/tap/tapctrlwrite3 /var/run/tap/tapctrlread3
>> tapdisk /var/run/tap/tapctrlwrite4 /var/run/tap/tapctrlread4
>> 
>> </SNIP>
>> 
>> Has anyone an idea why this happens on the new release?
>> 
>> Thanks,
>> Sascha
>> 
>> 
> 
> 
> 
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xensource.com
> http://lists.xensource.com/xen-devel
> 
> 

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Re: XEN 3.4 and blktapctrl

[Keir Fraser]

On 29/05/2009 22:30, "VM-Sascha" <sascha@argc.de> wrote:

> yes, that's the trick. Every tapctrl fifo gets now a own minor number.
> Now, the "tap:aio" is working as on XEN 3.3.1!

I'll sort out a patch for xen-unstable and xen-3.4 then. Thanks.

 -- Keir

Re: XEN 3.4 and blktapctrl

[Andy Burns]

2009/5/29 Keir Fraser <keir.fraser@eu.citrix.com>:

> If you build Xen 3.4
> yourself you can try reverting this patch with 'hg export 19349 | patch
> -Rp1' and rebuild the tools.

Not only does Sascha build xen, but generously makes the RPMs
available (for RHEL/centOS users) at

http://www.gitco.de/repo/xen3.4.0/

I use LVM partitions instead of tap:aio, but presume the 3.4.0-2
builds have this fix?