Re: [PATCH for-6.2 21/25] hw/timer/armv7m_systick: Use clock inputs instead of system_clock_scale

[Damien Hedde]

On 8/17/21 5:59 PM, Peter Maydell wrote:
> On Tue, 17 Aug 2021 at 16:55, Damien Hedde <damien.hedde@greensocs.com> wrote:
>>
>>
>>
>> On 8/12/21 11:33 AM, Peter Maydell wrote:
>> According to
>> https://developer.arm.com/documentation/ddi0403/d/System-Level-Architecture/System-Address-Map/The-system-timer--SysTick/SysTick-Calibration-value-Register--SYST-CALIB
>> , the field is 24bits wide.
>>
>> Should we prevent an overflow into the reserved bits and other fields ?
>> by doing something like this:
>>            val &= SYSCALIB_TENMS;
>> with the following #define with the other ones, above.
>>     #define SYSCALIB_TENMS ((1U << 24) - 1)
>>
>> Note, the overflow would happen around ~1.68GHz refclk frequency, it is
>> probably a config that will never happen. I'm not sure if we should care
>> or do something if this happens because it is probably an error
>> somewhere else.
> 
> I guess we should do something, yes, though pretty much anything
> we do will not really provide the guest with sensible data...
> I suppose masking out the higher bits is no worse than anything else.
> 
> -- PMM
> 


Then, with the masking.
Reviewed-by: Damien Hedde <damien.hedde@greensocs.com>

--
Damien