On Fri, 19 May 2017, Bogdan Mirea wrote:
> +#ifdef CONFIG_BOOT_TIME_PRESERVE
> +/*
> + * Set the real system time(including the time spent in bootloader)
> + * based on the timer counter.
> + */
> +
> +#ifndef BOOT_TIME_PRESERVE_CMDLINE
> + #define BOOT_TIME_PRESERVE_CMDLINE "preserve_boot_time"
> +#endif
> +void arch_timer_setsystime(void)
> +{
> + static struct timespec64 boot_ts;
> + static cycles_t cycles;
> + unsigned long long nsecs;
> +
> + if (!strstr(boot_command_line, BOOT_TIME_PRESERVE_CMDLINE))
> + return;
This adds a arch_timer specific command line option. Why is this arch_timer
specific? So if any other platform wants to gain this feature then we end
up copying that mess to every single timer implementation? Certainly NOT!
> +
> + cycles = arch_timer_read_counter() ? arch_timer_read_counter() : 0;
> +
> + nsecs = clocksource_cyc2ns(cycles, clocksource_counter.mult,
> + clocksource_counter.shift);
> + timespec64_add_ns(&boot_ts, nsecs);
> +
> + if (do_settimeofday64(&boot_ts))
> + pr_warn("arch_timer: unable to set systime\n");
What the heck is this? What has boot_ts to do with do_settimeofday()?
Exactly nothing. settimeofday() modifies CLOCK_REALTIME and if the platform
has an early accessible RTC, you hereby wreckaged wall_time. If the RTC
readout comes later then CLOCK_REALTIME is overwritten. So what is this
supposed to do?
It has absolutely nothing to do with CLOCK_BOOTTIME. /proc/uptime is based
on CLOCK_BOOTTIME, which is the CLOCK_MONOTONIC time since system boot. The
difference between CLOCK_MONOTONIC and CLOCK_BOOTTIME is that
CLOCK_MONOTONIC does not advance during suspend, but CLOCK_BOOTTIME takes
the suspended time into account.
I have not the faintest idea how you can claim that this patch actually
does what it is supposed to do. It's simply crap and CANNOT work at all.
Thanks,
tglx
