On Thu, May 05, 2011 at 04:07:19AM -0400, Ulrich Obergfell wrote:
>
> Hi Marcelo,
>
> > Other than that, shouldnt reset accounting variables to init state on
> > write to GLOBAL_ENABLE_CFG / writes to main counter?
>
> I'd suggest to initialize/reset the driftfix-related fields in the
> 'HPETTimer' structure (including the backlog of unaccounted ticks)
> in the following situations.
>
>
> - When the guest o/s sets the 'CFG_ENABLE' bit (overall enable) in
> the General Configuration Register.
>
> This is the place in hpet_ram_writel():
>
> case HPET_CFG:
> ...
> if (activating_bit(old_val, new_val, HPET_CFG_ENABLE)) {
> ...
> for (i = 0; i < s->num_timers; i++) {
> if ((&s->timer[i])->cmp != ~0ULL) {
> // initialize / reset fields here
> hpet_set_timer(&s->timer[i]);
>
>
> - When the guest o/s sets the 'TN_ENABLE' bit (timer N interrupt
> enable) in the Timer N Configuration and Capabilities Register.
>
> This is the place in hpet_ram_writel():
>
> case HPET_TN_CFG:
> ...
> if (activating_bit(old_val, new_val, HPET_TN_ENABLE)) {
> // initialize / reset fields here
> hpet_set_timer(timer);
>
>
> This should cover cases such as ...
>
> - first time initialization of HPET & timers during guest o/s boot.
> (includes kexec and reboot)
>
> - if a guest o/s stops and restarts the timer.
> (for example, to change the comparator register value or
> to switch a timer between periodic mode and non-periodic mode)
>
>
> Regards,
>
> Uli
Uli, looks good.
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