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Re: [Qemu-devel] [PATCH 2/2] Drop obsolete nographic timer
From: |
Marek Vasut |
Subject: |
Re: [Qemu-devel] [PATCH 2/2] Drop obsolete nographic timer |
Date: |
Fri, 16 Mar 2012 01:52:55 +0100 |
User-agent: |
KMail/1.13.7 (Linux/3.2.0-1-amd64; KDE/4.7.4; x86_64; ; ) |
Dear Jan Kiszka,
> On 2012-03-15 19:12, Marek Vasut wrote:
> > Dear Marek Vasut,
> >
> >> Dear Jan Kiszka,
> >>
> >>> On 2012-03-10 07:19, Marek Vasut wrote:
> >>>> Dear Jan Kiszka,
> >>>>
> >>>>> We flush coalesced MMIO in the device models now, and VNC - for which
> >>>>> this was once introduced - is also fine without it as it has its own
> >>>>> refresh timer.
> >>>>>
> >>>>> Signed-off-by: Jan Kiszka <address@hidden>
> >>>>> ---
> >>>>>
> >>>>> vl.c | 13 -------------
> >>>>> 1 files changed, 0 insertions(+), 13 deletions(-)
> >>>>
> >>>> This patch seems to break QEMU/PXA emulation for me on the ZipitZ2
> >>>> platform. The serial console became very slow, but only when I type
> >>>> something in. The output from the device to the console is ok. After
> >>>> reverting this particular one, the console behaves normally.
> >>>
> >>> Removing that timer removal likely just revealed some formerly hidden
> >>> bug. Can you share the command line used for starting and some test
> >>> image?
> >>>
> >>> Jan
> >>
> >> qemu-system-arm -M z2 -pflash flash.img -serial null -serial null
> >> -serial stdio -display none
> >>
> >> flash.img attached (XZ-ed)
> >
> > Bump?
>
> I had a brief look: The guest is apparently polling the uart, IRQ
> delivery is disabled.
Yes, it is.
> But it also receives no timer ticks. I haven't
> checked how it progresses, maybe there is some loop counter used.
What do you mean? How does the timer implementation in pxa-uboot work? udelay()
calls on the guest (pxa-uboot) simply poll the timer until it reaches certain
value. There's no paralelism going on at all.
>
> What's the origin of this test image? Have you checked it works properly
> on real silicon?
Yep.
> I do not know how this platform looks like in reality,
> how it should behave and should be programmed (by the guest), so I
> really can't compare and analyze, sorry.
I'm the maintainer, nice to meet you ;-) Real silicon is a small clamshell pc-
like device. But this breaks all xscale stuff in qemu.
>
> Jan
Best regards,
Marek Vasut