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Re: [Xen-devel] [PATCH] xen: more robust serial port driver

To: Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
Subject: Re: [Xen-devel] [PATCH] xen: more robust serial port driver
From: Christoph Egger <Christoph.Egger@xxxxxxx>
Date: Tue, 28 Jul 2009 17:03:11 +0200
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On Tuesday 28 July 2009 16:58:41 Keir Fraser wrote:
> On 28/07/2009 15:47, "Christoph Egger" <Christoph.Egger@xxxxxxx> wrote:
> >> Might this be the case for the udelay(100) as
> >> well?
> >
> > No. This ensures, that the write takes effect before the read happens.
> Can a read really overtake a write in this case? Seriously?

In real world this can happen on embedded devices, Xen doesn't support.
In simulators, things may differ from real hw.

> >> And what kinds of systems have these broken UARTs that half-advertise
> >> a broken/non-existent FIFO?
> >
> > The original ns16550 has a broken FIFO. The ns16450 has no FIFO.
> > There are simulators which simulate those old things instead of a
> > ns16550a.
> Hm, well, okay, the actual one line core of this patch actually seems okay
> to me. It's all the rest I want to drop on the floor.

Oh, I just noticed that there's a missing '__init' in the function definition
of check_existence. Please add it. Tnx.


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