Re: [Qemu-devel] [PATCH 2/2] Drop obsolete nographic timer

[Marek Vasut <marek.vasut@gmail.com>]

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 <jan.kiszka@siemens.com>
> >>>>> ---
> >>>>> 
> >>>>>  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