A follow up to my previous email. I see the same behavior with the command
qemu-system-i386 -sdl -icount 1 linux-0.2.img
On Sun, Nov 1, 2015 at 9:09 AM, James Nutaro <nut...@gmail.com> wrote:
> I have encountered the following unexpected behavior while trying to
> synchronize the virtual clock in qemu to a simulation clock in another
> software package. Is this something to be expected, or a bug that can
> be fixed?
>
> The issue can be reliably reproduced by making the following changes
> to qemu. In the file vl.c, add two lines to introduce the function
> qqq_setup. The diff against the main trunk is below.
>
> diff --git a/vl.c b/vl.c
> index f5f7c3f..0921969 100644
> --- a/vl.c
> +++ b/vl.c
> @@ -2932,6 +2932,8 @@ static void set_memory_options(uint64_t
> *ram_slots, ram_addr_t *
> }
> }
>
> +extern void qqq_setup(void);
> +
> int main(int argc, char **argv, char **envp)
> {
> int i;
> @@ -4641,6 +4643,7 @@ int main(int argc, char **argv, char **envp)
> }
> }
>
> + qqq_setup();
> main_loop();
> bdrv_close_all();
> pause_all_vcpus();
>
>
> The function qqq_setup starts a periodic timer as shown below.
>
> #include "qemu/timer.h"
> #include <stdio.h>
>
> static QEMUTimer* timer = NULL;
>
> static void timer_callback(void* data)
> {
> timer_mod(timer,qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL)+100);
> }
>
> void qqq_setup(void);
>
> void qqq_setup(void)
> {
> timer = timer_new_ms(QEMU_CLOCK_VIRTUAL,timer_callback,NULL);
> timer_mod(timer,qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL)+100);
> }
>
> I recompile qemu with these additions and boot a test image as follows
>
> qemu-system-i386 -sdl -icount 1,sleep=no linux-0.2.img
>
> The emulator stops after triggering the timer 23 times. After that,
> the emulation no longer progresses and the timer is not triggered.
> When I load this into gdb, what appears to be going on is that the
> emulator stops when all of the virtual cpu's become idle, at which
> time it hangs on the halt_cond conditional, which is never signaled.
> If I run without icount then everything works as expected.
>
> Any ideas?
