Re: [PATCH 2/4] target/arm: Abstract the generic timer frequency

[Andrew Jeffery]

On Tue, 3 Dec 2019, at 04:42, Peter Maydell wrote:
> On Thu, 28 Nov 2019 at 05:44, Andrew Jeffery <address@hidden> wrote:
> >
> > Prepare for SoCs such as the ASPEED AST2600 whose firmware configures
> > CNTFRQ to values significantly larger than the static 62.5MHz value
> > currently derived from GTIMER_SCALE. As the OS potentially derives its
> > timer periods from the CNTFRQ value the lack of support for running
> > QEMUTimers at the appropriate rate leads to sticky behaviour in the
> > guest.
> >
> > Substitute the GTIMER_SCALE constant with use of a helper to derive the
> > period from gt_cntfrq stored in struct ARMCPU. Initially set gt_cntfrq
> > to the frequency associated with GTIMER_SCALE so current behaviour is
> > maintained.
> >
> > Signed-off-by: Andrew Jeffery <address@hidden>
> 
> > +static inline unsigned int gt_cntfrq_period_ns(ARMCPU *cpu)
> > +{
> > +    /* XXX: Could include qemu/timer.h to get NANOSECONDS_PER_SECOND? */
> > +    const unsigned int ns_per_s = 1000 * 1000 * 1000;
> > +    return ns_per_s > cpu->gt_cntfrq ? ns_per_s / cpu->gt_cntfrq : 1;
> > +}
> 
> This function is named gt_cntfrq_period_ns()...
> 
> >  static uint64_t gt_virt_cnt_read(CPUARMState *env, const ARMCPRegInfo *ri)
> >  {
> > +    ARMCPU *cpu = env_archcpu(env);
> > +
> >      /* Currently we have no support for QEMUTimer in linux-user so we
> >       * can't call gt_get_countervalue(env), instead we directly
> >       * call the lower level functions.
> >       */
> > -    return cpu_get_clock() / GTIMER_SCALE;
> > +    return cpu_get_clock() / gt_cntfrq_period(cpu);
> >  }
> 
> ...but here we call gt_cntfrq_period(), which doesn't exist,
> and indeed at least one of the patchew build systems reported
> it as a compile failure.
> 

Ah yep, I failed to test user mode after renaming the function and missed this.

I haven't seen an alert from patchew though, I wonder where that got to?

Andrew