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Re: [Xen-users] Is Xen and Qemu serial driver code related ?

To: "Aleš Rom" <ales.rom@xxxxxxxxxxxx>
Subject: Re: [Xen-users] Is Xen and Qemu serial driver code related ?
From: "Ulrich Windl" <ulrich.windl@xxxxxxxxxxxxxxxxxxxx>
Date: Mon, 12 Feb 2007 09:17:46 +0100
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On 10 Feb 2007 at 10:13, Ales Rom wrote:

> On the other way, emulated serial port is not acting the same as real
> one. Is this question for xen developers? Can I try anything else?

The timing for the serial port at high baud rates can be critical (that is, you
may miss received characters, or you may not fill the UART's transmit buffer in
time). That's why I suggested to try a fault-tolerant transfer protocol like
kermit: Youz can disconnect the cable, then reconnect it, and the transfer will
continue (much like TCP). I know that there are "industry style" protocols 
that are not fault tolerant like that. I had real trouble upgrading the firmware
of a GPS unit via serial cable, completely without XEN: One bad character, and 
unit had to be powered off and on again. That bad thing was that exactly that
power cycle placed on invalid character in the PC's receive buffer, and the
protocol failed. Hard life, this life ;-)


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