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Re: [Xen-devel] Help/problems with blktap on xen-unstable

To: Christophe Saout <christophe@xxxxxxxx>
Subject: Re: [Xen-devel] Help/problems with blktap on xen-unstable
From: Steven Rostedt <srostedt@xxxxxxxxxx>
Date: Wed, 20 Sep 2006 14:35:49 -0400
Cc: Roland Paterson-Jones <roland@xxxxxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxx
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Christophe Saout wrote:
Am Mittwoch, den 20.09.2006, 08:37 +0200 schrieb Roland Paterson-Jones:

I've been trying to play with the new blktap support in xen-unstable.

First, an observation - blktapctrl is pinned at 100% CPU:

Do you have a 3Ware controller or something? On my machine, the
controller management interface (/dev/twe*) gets assigned the major 254,
and XEN has the same major hardcoded, and the registration therefore
fails. blktapctrl then creates its device nodes /dev/xen/tapctrl* with
major 254 and tries to talk to it. The twe driver doesn't understand its
ioctl's and blktapctrl tries to resend its commands in an infinite loop.

The plan (according to blktap.c) is to make the registration of the
device node major number dynamic:

#define BLKTAP_DEV_MAJOR 254         /* TODO: Make major number dynamic  *
                                      * and create devices in the kernel *

Nobody has done so yet.

Any thought about making blktap a miscellaneous device and have blkctrl just read /proc/misc to find the node? I could easily write up a patch, if others think this is appropriate.

-- Steve

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