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Re: [Xen-tools] [PATCH] An example console driver using the store

To: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
Subject: Re: [Xen-tools] [PATCH] An example console driver using the store
From: Anthony Liguori <aliguori@xxxxxxxxxx>
Date: Mon, 08 Aug 2005 12:37:22 -0500
Cc: Xen Tools <xen-tools@xxxxxxxxxxxxxxxxxxx>, hollis <hollisb@xxxxxxxxxx>, Ian Pratt <Ian.Pratt@xxxxxxxxxxxx>, Jimi Xenidis <jimix@xxxxxxxxxx>, Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>, Robert Read <robert@xxxxxxxxxxxxx>
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Hi Rusty,

One thing we might want to consider doing is having the domain builder allocate a page/event channel for the first console. This gives us access to the console in a guest at start of day (and would work even if the store is not running). I think this later reason is particuarily important since it's hard to debug the XenBus code in a guest without a console.

Also, it allows the PPC guys to hack up the hypervisor to support the PAPR console stuff since they can get to the ring buffer by examining the shared_info_frame. It's not a long term solution but it's useful.



Anthony Liguori

Rusty Russell wrote:

Sorry this took so long, distracted by other things.

This patch adds xenbus_early_write, for use before we can sleep, and
illustrates how a console driver can use the store.  The console driver
replaces the normal one for testing, and uses the same ringbuf code as
xenbus (which really should be extracted into a separate library).

The toy client only handles a single page for the buffer, doesn't handle
^C etc.

This uncovered some bugs in xenstored: patches coming. Cheers!

Signed-off-by: Rusty Russell <rusty@xxxxxxxxxxxxxxx>

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