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Re: GRUB really slow to boot



On Sun, Dec 19, 2021 at 07:19:40AM +0000, Tim Woodall wrote:
> Check if the kernel log jumps from 1/1/70 to today as it boots. That
> would point to the RTC being bad when the kernel first starts.

Not sure which log I'd need to look at for this information.  dmesg only
reports time in relative seconds from the kernel's boot.

/var/log/kern.log.1 shows this:

Dec 18 09:58:48 unicorn kernel: [6031224.812397] xor: automatically using best c
hecksumming function   avx       
Dec 18 09:58:48 unicorn kernel: [6031224.944868] Btrfs loaded, crc32c=crc32c-int
el
Dec 18 11:17:28 unicorn kernel: [    0.000000] microcode: microcode updated earl
y to revision 0xea, date = 2021-01-05
Dec 18 11:17:28 unicorn kernel: [    0.000000] Linux version 5.10.0-10-amd64 (de
bian-kernel@lists.debian.org) (gcc-10 (Debian 10.2.1-6) 10.2.1 20210110, GNU ld 
(GNU Binutils for Debian) 2.35.2) #1 SMP Debian 5.10.84-1 (2021-12-08)

Of course, the human-readable timestamps on the left come from syslog,
which is a userspace process that is launched after the clock is
initialized from whatever sources (not sure exactly when NTP kicks in).

The one-hour jump is, I think, an artifact of daylight saving time
ending between my last two boots.  The 09:58 lines are from the syslog
which was initialized while I was on daylight saving time (in October),
and the 11:17 lines are from the syslog that was launched on standard
time in December.  I see similar time shenanigans in the output of last:

greg     pts/5        :pts/0:S.1       Sat Dec 18 10:18   still logged in
greg     pts/4        :pts/0:S.0       Sat Dec 18 10:18   still logged in
greg     tty1                          Sat Dec 18 11:17   still logged in
reboot   system boot  5.10.0-10-amd64  Sat Dec 18 06:17   still running
tester   tty2                          Mon Nov 22 11:18 - 11:18  (00:00)
greg     pts/12       :pts/2:S.8       Sat Oct  9 15:39 - 10:14 (69+19:35)

The "reboot" line shows 6:17 which might be accurate UTC.  The line
immediately above that is 11:17 (5-hour offset for US/Eastern), and
the line above that is 10:18 (a weird one-hour jump backward which I
can only guess is somehow related to daylight saving time).


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