From mboxrd@z Thu Jan  1 00:00:00 1970
From: Rob Gardner <rob.gardner@hp.com>
Subject: Re: [PATCH] Make xentrace hypercall a bit more sane
Date: Thu, 01 Jun 2006 14:24:33 -0600
Message-ID: <447F4D01.1080700@hp.com>
References: <de76405a0606011317qe1fed70u1eb52e6046d32246@mail.gmail.com>
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To: George Dunlap <dunlapg@umich.edu>
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George Dunlap wrote:
> xentrace, setsize and the hypervisor don't seem to be on the same
> page.  If tracing is not enabled, the hypercall will only allow
> TBUF_SET_SIZE and TBUF_ENABLE.  However, set_size calls TBUF_GET_INFO,
> and xentrace wants to call TBUF_SET_EVT_MASK and TBUF_SET_CPU_MASK
> before calling TBUF_ENABLE.
>
> I don't see any reason not to call SET_*_MASK and GET_INFO if tracing
> is not enabled.    If the buffer hasn't been allocated yet, GET_INFO
> should just return something invalid in the mfn field.  Anyone calling
> should check this value.
>

Sounds benign enough. I never liked the behavior of disallowing the 
get_info call.

Rob