Re: [Qemu-devel] Slow clock in guest OS

[Sergey Bychkov]

----- Original Message ----- 
From: "Mulyadi Santosa" <address@hidden>
To: <address@hidden>
Sent: 25.01.2008 14:02


> > Yes, it helps, in some extent.
> > With rtc/max-user-freq set to 1024 and "-clock rtc" option VM now works 
> > like
> > in 0.8.2 version.
> > Clock is slower than in host, but Windows Time server could correct this, 
> > if
> > started.
> > Busy host or guest CPU slows down clock.
>
> I remember somebody wrote dyntick patch...but not sure if it is
> already merged into qemu CVS.

Yes, it merged (I thought it is the default). Now I tried to test VM with 
it - Win2k3 hangs on boot, on the stage, afaik, switching to protected mode.

> Maybe you need similar trick like win98 to halt CPU when not doing 
> anything?

Win2k3 has NT kernel (like in WinXP/2000) and does't require this. When 
guest OS is idle, qemu uses only few percents of host CPU, and guest clock 
didn't lose too much.

> > Sometimes VM hangs on start.
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ this is weird.... can you dump
> the generated opcode? pls see qemu-doc/tech for more detail on how to
> do it.

May be I will try to work with this problem later and report it in different 
thread.

> > Htop shows that qemu uses 100% of second CPU in
> > user mode.
>
> Before I forgot, do you use kqemu? if yes, do you full virtualization 
> mode?

Yes. No.
But I have got this problem sometimes with -kernel-kqemu and with -no-kqemu 
options.

> > Internal QEMU VNC server listens port but doesn't accepts
> > connections, so vncviewer hangs too. If used GUI, is shows monitor 
> > prompt,
> > that doesn't accept any keyboard input. Could be killed by Ctrl-C in 
> > console
> > or 'kill -9'. May be it's different problem but they happen both on the 
> > same
> > host hardware.
> very weird....do you use precompiled qemu binary? or do you compile by
> yourself? if it is compiled by yourself, what gcc version do you use?

Previous (stable) version of qemu 0.8.2 was from Debian Etch amd64 
(x86_64) - precompiled.
Yesterday's snapshot (qemu-snapshot-2008-01-24_05) compiled manually with 
GCC-4, for targets x86_64-softmmu, i386-softmmu.
==
$ 
./configure --disable-gcc-check --disable-gfx-check --target-list="i386-softmmu 
x86_64-softmmu" --prefix=$HOME
make
make install
==
qemu-system-x86_64 only used, because host OS is x86_64 and I want kqemu to 
be used.
Win2k3 is 32bit version.

PS There is no documentation about "-clock" option in latest qemu documents, 
exept source code, of cause :)

Yours sincerely,
Sergey Bychkow
ICQ: 21014758
FTN: 2:450/118.55