Subject: Re: port-xen/29775: Cannot use a vnode disk for domU
To: None <bouyer@netbsd.org, gnats-admin@netbsd.org, netbsd-bugs@netbsd.org>
From: YAMAMOTO Takashi <yamt@mwd.biglobe.ne.jp>
List: netbsd-bugs
Date: 03/30/2005 23:11:02
The following reply was made to PR kern/29775; it has been noted by GNATS.

From: YAMAMOTO Takashi <yamt@mwd.biglobe.ne.jp>
To: thorpej@shagadelic.org
Cc: tech-kern@NetBSD.org, port-xen-maintainer@NetBSD.org,
	gnats-admin@NetBSD.org, netbsd-bugs@NetBSD.org, gnats-bugs@NetBSD.org
Subject: Re: port-xen/29775: Cannot use a vnode disk for domU
Date: Thu, 31 Mar 2005 08:10:04 +0900

 hi,
 
 > > This means that I/O on the vnd block device expect to be called from
 > > a process context, while the xbd backend calls it from interrupt  
 > > context.
 > > And obvious way to fix this would be to add a kernel thread to the  
 > > xbd backend
 > > to do this. But maybe this needs a closer look:
 > 
 > This is really a known problem.  The vnd driver needs to be rewritten  
 > badly.  It needs to queue up requests and defer everything to a  
 > kthread that actually does the work.
 > 
 > -- thorpej
 
 do you really think VOP_STRATEGY should be usable from interrupt context?
 
 YAMAMOTO Takashi