RPI4 clock speeds and serial port ( temperatures idle and -j4 buildworld buildkernel )

[Mark Millard]

On 2021-Mar-19, at 10:43, bob prohaska <fbsd at www.zefox.net> wrote:

> On Thu, Mar 18, 2021 at 10:14:26PM -0700, Mark Millard wrote:
>> 
>> World build completed on Thu Mar 18 21:31:44 PDT 2021
>> World built in 29705 seconds, ncpu: 4, make -j4
>> . . .
>> Kernel build for GENERIC-NODBG completed on Thu Mar 18 22:10:02 PDT 2021
>> Kernel(s)  GENERIC-NODBG built in 2298 seconds, ncpu: 4, make -j4
>> 
>> So somewhat under 9 hours.
>> 
> 
> So my figures (~17 hours) seem reasonable for a default clocking.
> I thought maybe I'd done something wrong.
> 
> For now I'll leave the clocking alone. But some puzzles remain:
> It appears that the CPU and the GPU have separate clocks. Can they
> be set separately, and does the GPU have any practical effect on
> FreeBSD's behavior once boot is complete? 

See:

https://www.raspberrypi.org/documentation/configuration/config-txt/overclocking.md

It says that setting gpu_freq sets core_freq and also says:

QUOTE
Changing core_freq in config.txt is not supported on the Pi 4
any change from the default will almost certainly cause a
failure to boot.
END QUOTE

and:

QUOTE
It is recommended when overclocking to use the individual
frequency settings (isp_freq, v3d_freq etc) rather than gpu_freq,
as since it attempts to set core_freq (which cannot be changed on]
the Pi 4), it is not likely to have the desired effect.
END QUOTE

There is more about the relationships to hdmi_enable_4kp60 and
enable_tvout.

===
Mark Millard
marklmi at yahoo.com
( dsl-only.net went
away in early 2018-Mar)