From nobody Sun Apr 5 18:40:25 2026 X-Original-To: freebsd-current@mlmmj.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mlmmj.nyi.freebsd.org (Postfix) with ESMTP id 4fph9M4LYLz6Wrxy for ; Sun, 05 Apr 2026 18:40:39 +0000 (UTC) (envelope-from julian@freebsd.org) Received: from vps1.elischer.org (vps1.elischer.org [204.109.63.16]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (2048 bits) client-digest SHA256) (Client CN "vps1.elischer.org", Issuer "R12" (not verified)) by mx1.freebsd.org (Postfix) with ESMTPS id 4fph9L2lrqz3mlZ for ; Sun, 05 Apr 2026 18:40:38 +0000 (UTC) (envelope-from julian@freebsd.org) Authentication-Results: mx1.freebsd.org; dkim=none; dmarc=fail reason="No valid SPF, No valid DKIM" header.from=freebsd.org (policy=none); spf=softfail (mx1.freebsd.org: 204.109.63.16 is neither permitted nor denied by domain of julian@freebsd.org) smtp.mailfrom=julian@freebsd.org Received: from [10.0.0.12] (c-67-189-70-178.hsd1.wa.comcast.net [67.189.70.178]) (authenticated bits=0) by vps1.elischer.org (8.17.2/8.16.1) with ESMTPSA id 635IeUHM076710 (version=TLSv1.3 cipher=TLS_AES_128_GCM_SHA256 bits=128 verify=NOT) for ; Sun, 5 Apr 2026 11:40:31 -0700 (PDT) (envelope-from julian@freebsd.org) X-Authentication-Warning: vps1.elischer.org: Host c-67-189-70-178.hsd1.wa.comcast.net [67.189.70.178] claimed to be [10.0.0.12] Content-Type: multipart/alternative; boundary="------------awzGuh0oQxp6WdPfJfBIM9KJ" Message-ID: Date: Sun, 5 Apr 2026 11:40:25 -0700 List-Id: Discussions about the use of FreeBSD-current List-Archive: https://lists.freebsd.org/archives/freebsd-current List-Help: List-Post: List-Subscribe: List-Unsubscribe: Sender: owner-freebsd-current@FreeBSD.org MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: Getting boottime early in booting To: freebsd-current@freebsd.org References: Content-Language: en-US From: julian@freebsd.org In-Reply-To: X-Spamd-Result: default: False [-2.34 / 15.00]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_SHORT(-0.98)[-0.980]; NEURAL_HAM_MEDIUM(-0.56)[-0.557]; ONCE_RECEIVED(0.20)[]; MIME_GOOD(-0.10)[multipart/alternative,text/plain]; DMARC_POLICY_SOFTFAIL(0.10)[freebsd.org : No valid SPF, No valid DKIM,none]; RCVD_VIA_SMTP_AUTH(0.00)[]; ARC_NA(0.00)[]; ASN(0.00)[asn:36236, ipnet:204.109.60.0/22, country:US]; FREEFALL_USER(0.00)[julian]; FROM_NO_DN(0.00)[]; RCVD_COUNT_ONE(0.00)[1]; MIME_TRACE(0.00)[0:+,1:+,2:~]; TO_DOM_EQ_FROM_DOM(0.00)[]; MID_RHS_MATCH_FROM(0.00)[]; R_DKIM_NA(0.00)[]; R_SPF_SOFTFAIL(0.00)[~all]; FROM_EQ_ENVFROM(0.00)[]; HAS_XAW(0.00)[]; RCPT_COUNT_ONE(0.00)[1]; TO_DN_NONE(0.00)[]; PREVIOUSLY_DELIVERED(0.00)[freebsd-current@freebsd.org]; TO_MATCH_ENVRCPT_ALL(0.00)[]; MLMMJ_DEST(0.00)[freebsd-current@freebsd.org]; RCVD_TLS_ALL(0.00)[] X-Rspamd-Queue-Id: 4fph9L2lrqz3mlZ X-Spamd-Bar: -- This is a multi-part message in MIME format. --------------awzGuh0oQxp6WdPfJfBIM9KJ Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit > 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 --------------awzGuh0oQxp6WdPfJfBIM9KJ Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: 8bit 



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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