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[Xen-devel] Re: [PATCH resend] allow connecting to xenconsole from remot

To: Muli Ben-Yehuda <muli@xxxxxxxxxx>
Subject: [Xen-devel] Re: [PATCH resend] allow connecting to xenconsole from remote hosts
From: Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>
Date: Tue, 26 Sep 2006 16:50:37 +0100
Cc: Jimi Xenidis <jimix@xxxxxxxxxxxxxx>, xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx>, Anthony Liguori <anthony@xxxxxxxxxxxxx>, Orran Y Krieger <okrieg@xxxxxxxxxx>
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Thread-topic: [PATCH resend] allow connecting to xenconsole from remote hosts
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On 26/9/06 16:26, "Muli Ben-Yehuda" <muli@xxxxxxxxxx> wrote:

> The attached patch makes xenconsole send and receive console messages
> over a remote connection, instead of via stdin/stdout - if given the
> --remote switch. It is useful for proxy'ing real console message or
> other protocol messages (such as gdb) between dom0 and a remote
> host. We're currently using it for proxying gdb between gdbstub in a
> partition that talks gdb over the console page to a remote host
> running gdb.
> Changed since last version:
> - fixed compile warning - type of 'buf' in handle_read_fd() should be
>   char*, not unsigned char*.
> Signed-off-by: Muli Ben-Yehuda <muli@xxxxxxxxxx>

I should have spotted this before, but I'm unsure whether the message buffer
ring stuff is really needed. On the write (to the guest) side, we only read
from the tty_fd (or socket in your case) if there is space in the shared
console ring. On the read (from the guest) side, we already have a buffer
(see e.g., buffer_append() in console/daemon/io.c). It may not be the best
buffer code, and we may want to change it in future to support logging to
files, but it does work! So can you not just send a minimal patch to add
socket support? It should be really small (like 10s of lines).

 -- Keir

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