--------
Javier Herrero writes:
> - To implement a counter in the FPGA for use as the Linux clock source,
> instead of the ARM timer
> - Implement harware timestamping on the PPS, and generate the interrupt
> (and since I was there, I use an external clock source for the counter
> like the GPSO that gives also the PPS signal, instead of the usually
> crappy XO that drives the Zynq clocks)
> - And then have a lot of fun convincing the kernel to use the FPGA
> counter as clock source, and converting raw PPS timestamp times to wall
> clock in the kernel, to be able to give a good timestamp value to ntp/chrony
In FreeBSD you get all that for free:
https://papers.freebsd.org/2002/phk-timecounters.files/timecounter.pdf
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
[email protected] | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
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