Le mar. 25 août 2020 18:09, Peter Maydell <peter.maydell@linaro.org> a
écrit :
> It is the responsibility of board code for an armv7m system to set
> system_clock_scale appropriately for the CPU speed of the core.
> If it forgets to do this, then QEMU will hang if the guest tries
> to use the systick timer in the "tick at the CPU clock frequency" mode.
>
> We forgot that in a couple of our boards (see commits ce4f70e81ed23c93f,
> e7e5a9595ab1136). Add an assertion in the systick reset method so
> we don't let any new boards in with the same bug.
>
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
---
> In the longer term we should make this a clocktree input and
> plumb it through the armv7m container and so on, but for the
> moment this assert() improves the current situation.
> ---
> hw/timer/armv7m_systick.c | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
> diff --git a/hw/timer/armv7m_systick.c b/hw/timer/armv7m_systick.c
> index 74c58bcf245..a8cec7eb56b 100644
> --- a/hw/timer/armv7m_systick.c
> +++ b/hw/timer/armv7m_systick.c
> @@ -202,6 +202,14 @@ static void systick_reset(DeviceState *dev)
> {
> SysTickState *s = SYSTICK(dev);
>
> + /*
> + * Forgetting to set system_clock_scale is always a board code
> + * bug. We can't check this earlier because for some boards
> + * (like stellaris) it is not yet configured at the point where
> + * the systick device is realized.
> + */
> + assert(system_clock_scale != 0);
> +
> s->control = 0;
> s->reload = 0;
> s->tick = 0;
> --
> 2.20.1
>
>
>