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Re: [Xen-devel] domU console buffer behaviour

To: Ferenc Wagner <wferi@xxxxxxx>, <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject: Re: [Xen-devel] domU console buffer behaviour
From: Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
Date: Mon, 29 Dec 2008 21:00:14 +0000
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On 29/12/2008 20:14, "Ferenc Wagner" <wferi@xxxxxxx> wrote:

> That is, the first 158 lines were dropped and the last 128 lines were
> overwritten.  As formatting is such that each line is 16 bytes, it
> means that the last 2 kiB was sort of following the guest console
> output, but in a broken way: lines between 72285--72302 were lost.
> Only the last 16 lines (256 bytes) are really fresh.
> All of this feels rather fishy.  Can anybody provide some insight,
> please?  Is this expected?  Is my config broken?  Or is this a bug?

I think the console daemon tries to discard contiguous chunks of data,
rather than odd characters here and there. How effective it really is I'm
not sure, but certainly you can expect the discards to be in
reasonable-sized chunks and also to be pretty random. Why do you think this
has something to do with pv_ops lockups?

 -- Keir

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