Date: Sun, 5 Apr 2026 11:40:25 -0700 From: julian@freebsd.org To: freebsd-current@freebsd.org Subject: Re: Getting boottime early in booting Message-ID: <be0c0ec5-12b1-4274-a67e-02deae93d3af@freebsd.org> In-Reply-To: <adDJKGKnBrj0wCZc@kib.kiev.ua> References: <CAM5tNy4mPmG=OmQtiGrMQ8NnPZrN=dw_Xw1h9=s4iyOLiZCWng@mail.gmail.com> <CANCZdfrS6YbL2JCe=MgQL1==CL-x4hL=AEAvjJRdiK-8URARWg@mail.gmail.com> <adCB5JLDgnoYNrXI@kib.kiev.ua> <CAM5tNy7kJ3NxA3Lt0Yj_e285mX5FoBUH8%2BCFDaLAiV%2B1bBywtg@mail.gmail.com> <adDJKGKnBrj0wCZc@kib.kiev.ua>
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> On Sat, Apr 04, 2026 at 12:37:52AM -0700, Rick Macklem wrote:
For this the RTC chip was invented and connected to a battery.
I'm also guessing that you don't need "universally unique in time" but
"different from the last boot".
I once used the information available in a system as to whether this was
a warn or cold boot (not all systems have that but we did) along with
low bits from the microseconds from the counter timer.. as soon as
reality strikes that tends to become pseudorandom pretty quickly. you'll
need a different one for each architecture to I like the suggestion to
use the entropy collection where you can piggyback on other people's work.
julian
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<pre wrap="" class="moz-quote-pre">On Sat, Apr 04, 2026 at 12:37:52AM -0700, Rick Macklem wrote:
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<p>For this the RTC chip was invented and connected to a battery.<br>
</p>
<p>I'm also guessing that you don't need "universally unique in
time" but "different from the last boot".<br>
I once used the information available in a system as to whether
this was a warn or cold boot (not all systems have that but we
did) along with low bits from the microseconds from the counter
timer.. as soon as reality strikes that tends to become
pseudorandom pretty quickly. you'll need a different one for each
architecture to I like the suggestion to use the entropy
collection where you can piggyback on other people's work.<br>
<br>
julian<br>
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