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[Xen-devel] Re: [Xen-staging] [xen-unstable] [QEMU-DM] Upgrade emulated UART to 16550A.
- To: xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx>, "Keir Fraser" <Keir.Fraser@xxxxxxxxxxxx>
- From: "Trolle Selander" <trolle.selander@xxxxxxxxx>
- Date: Fri, 7 Dec 2007 18:51:42 +0100
- Delivery-date: Fri, 07 Dec 2007 09:52:21 -0800
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- List-id: Xen developer discussion <xen-devel.lists.xensource.com>
I'll look into it further, though I'm a bit puzzled as to why it was
faster before - the old code would attempt to retransmit every 100ms,
for up to 300ms. That's a LOT longer than my code will retry at any
kind of sane baud-rates. What guest are you running in the HVM?
At one point I was considering adding a "backend type" field for
the qemu char devices to prevent having to detect if the backend device
was a physical port from within serial.c. Perhaps I'll need to go back
to that plan and treat pty's differently, or simply skip the transmit
retries entirely when the backend isn't a physical serial port.
On Dec 7, 2007 6:21 PM, Alex Williamson < alex.williamson@xxxxxx> wrote:
On Wed, 2007-12-05 at 23:07 +0100, Trolle Selander wrote:
> This patch fixes the issue. It also changes the name of an
> inappropriately named timer.
Hi Trolle,
Yes, with this patch, my HVM domain will eventually boot.
Unfortunately it takes 2 minutes now to get through all the UART
timeouts and get to the firmware menu. Prior to the new 16550A UART
driver, it took 10 seconds. I think we need to do something smarter
than drop characters after some number of timeouts. We're doomed to
terrible slowness anytime the console is disconnected that way. Thanks,
Alex
--
Alex Williamson HP Open Source & Linux Org.
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