On Wed, May 30, 2018 at 12:20 PM, Feng Tang <[email protected]> wrote:
> To show time info in kernel log earlier and help optimizing kernel
> boot time, printk adds a debug hook "boot_printk_clock_fn()" for
> capable platform which has accurate clock in early boot phase.
>
> This patch will add early param setup option, so that user can
> chose to provide a tsc based early printk clock simply by adding
> in command line: "boot_tsc=xxxxM" (xxxxM is the stable TSC freq).
> +
This line is not needed.
> + cur_tsc = rdtsc();
> + cur_tsc -= boot_tsc_offset;
In one expression?
> + if (!p)
> + return -EINVAL;
> +
I'm not sure it's needed at all.
> + boot_tsc_mhz = div64_u64(tsc_hz, 1024 * 1024);
Hmm... 1024*1024 != 1000 * 1000. So, hz -> mhz here (as by suffixes)
looks weird.
> + if (boot_tsc_mhz == 0)
> + return -EINVAL;
> + pr_info("TSC has run for %lld us\n",
> + div64_u64(boot_tsc_offset, boot_tsc_mhz));
> +
> + /* Setup the early printk clock */
> + boot_printk_clock_fn = boot_tsc_clock;
> + pr_info("TSC: Setup early printk timestamp with %lldM TSC.",
> + boot_tsc_mhz);
Perhaps remove period (above doesn't have it) and move this to one line?
--
With Best Regards,
Andy Shevchenko
