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From: "Erik E. Fair" <fair-tuhs@netbsd.org>
To: Pat Barron <patbarron@acm.org>
Cc: tuhs@tuhs.org
Subject: Re: [TUHS] Paper discussing Unix boot process?
Date: Wed, 10 Apr 2019 10:20:14 -0700	[thread overview]
Message-ID: <17458.1554916814@cesium.clock.org> (raw)
In-Reply-To: <alpine.LFD.2.21.1904101246310.2133@booboo.lectroid.com>

Pat,
	Any such description is either going to be very hardware/system specific, or vague to the point of uselessness. The experience of the NetBSD community, which prides itself on extreme portability and working around broken or  ... let's say "incomplete" vendor firmware, is that such things are highly system-specific.

The vague description is easy:

	some booter or firmware loads the kernel into RAM,

	the kernel initializes the MMU and the rest of the processor(s),
	devices are somehow probed or listed and device drivers called to
	initialize minimally necessary I/O devices (console, data storage so
	you can mount / (root)),

	a process is created, and /sbin/init is exec'd.

Details of firmware or booter provided environment and parameters to the kernel vary a lot; thus that famously small-ish percentage of any Unix kernel that is written in assembler for the processor involved, rather than C.

See also

https://www.quora.com/Are-bootloaders-like-GRUB-and-LILO-hardware-specific/answer/Erik-Fair

https://www.quora.com/What-is-a-concise-explanation-for-the-UNIX-bootstrap-process/answer/Erik-Fair

	Erik

  reply	other threads:[~2019-04-10 17:32 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-04-10 16:51 Pat Barron
2019-04-10 17:20 ` Erik E. Fair [this message]
2019-04-10 17:57 ` Dan Cross
2019-04-19 22:31 ` Chris Hanson
2019-04-10 18:02 Pat Barron
2019-04-10 18:14 ` Erik E. Fair
2019-04-10 18:28   ` Clem Cole
2019-04-10 19:05     ` Bakul Shah
2019-04-10 22:24       ` Clem Cole
2019-04-10 22:53         ` Warren Toomey
2019-04-11  1:45           ` Greg 'groggy' Lehey
2019-04-10 23:19         ` Bakul Shah
2019-04-11  4:52           ` Fabio Scotoni
2019-04-11 13:48             ` Clem Cole
2019-04-11 14:54               ` Dan Cross
2019-04-11 15:36                 ` Clem Cole
2019-06-26  2:28             ` Peter Jeremy
2019-06-26  7:57               ` Bakul Shah
2019-04-11  1:06 Pat Barron
2019-04-11  1:27 ` Charles Anthony
2019-04-11  2:26 ` Erik E. Fair
2019-04-13 18:35 Noel Chiappa
2019-04-16 12:52 Noel Chiappa
2019-04-17  5:35 Paul Ruizendaal
2019-04-17 18:26 ` Warner Losh

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