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Re: [Xen-devel] blktap failure after 14895:800aa9f5cec9 (moves /dev/xen/

To: Keir Fraser <keir@xxxxxxxxxxxxx>
Subject: Re: [Xen-devel] blktap failure after 14895:800aa9f5cec9 (moves /dev/xen/... to /var/run/tap/...)
From: Brendan Cully <brendan@xxxxxxxxx>
Date: Wed, 2 May 2007 08:11:35 -0700
Cc: Xen Developers <xen-devel@xxxxxxxxxxxxxxxxxxx>
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On Wednesday, 02 May 2007 at 13:51, Keir Fraser wrote:
> On 2/5/07 03:48, "Brendan Cully" <brendan@xxxxxxxxx> wrote:
> > I don't know why I'm the only one to see this, but blktap hasn't been
> > working for me since 14895:800aa9f5cec9. Opening /var/run/tap/blktap0
> > fails. I think this is because the kernel defines BLKTAP_DEV_DIR as
> > /dev/xen in drivers/xen/blktap/blktap.c, but in that changeset the
> > tools define it as /var/run/tap in tools/blktap/lib/blktaplib.h.
> > 
> > Reverting the change to blktaplib.h gives me blktap devices
> > again. Reads and writes don't seem to make any progress. I'll keep
> > investigating, but any clues would be welcome.
> More likely it's simply because /var/run/tap/ doesn't exist?
> Either some startup script needs to 'mkdir -p', or blktapctrl needs to make
> the directory on demand.

the blktap tools do create that directory on demand, and in fact
/var/run/tap/blktap0 is properly created. What fails is the 'open',
somewhere in the kernel I believe. Maybe this only affects
block-attaching a device in domain 0?

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