On 2012-03-16 01:52, Marek Vasut wrote: > 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.kis...@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.
I'm starting to understand the issue: The serial port can only accept a
single byte. Once this arrived, serial_can_receive1 returns 0, and the
backend fd is not longer polled by the io-thread. This should change
again as soon as the guest read that byte. But qemu_chr_accept_input,
which is properly called by the serial device, didn't kick the io-thread
in some way. I solved it this way now:
diff --git a/qemu-char.c b/qemu-char.c
index 9a5be75..a589a84 100644
--- a/qemu-char.c
+++ b/qemu-char.c
@@ -177,6 +177,7 @@ void qemu_chr_accept_input(CharDriverState *s)
{
if (s->chr_accept_input)
s->chr_accept_input(s);
+ qemu_notify_event();
}
void qemu_chr_fe_printf(CharDriverState *s, const char *fmt, ...)
But I'm not yet sure if this is correct. Comments welcome!
Jan
signature.asc
Description: OpenPGP digital signature
