Wiki source code of Openwrt Notes
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| author | version | line-number | content |
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1.1 | 1 | |
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| 3 | = initramfs-kernel = | ||
| 4 | |||
| 5 | kernel runs /init. | ||
| 6 | |||
| 7 | /init is a script which sets INITRAMFS=1 and then execs /sbin/init. | ||
| 8 | |||
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2.1 | 9 | /sbin/init is ELF comes from procd package. What it does (as pid=1): |
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1.1 | 10 | |
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4.1 | 11 | * early (different from procd early): |
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1.1 | 12 | ** mount /proc, /sysfs, and create /dev nodes, create /tmp subdirs etc |
| 13 | ** set PATH | ||
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3.1 | 14 | * kmodloader in subprocess (waits until done) |
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1.1 | 15 | * preinit |
| 16 | ** plugd in subprocess (seem to deal with firmware) | ||
| 17 | ** /etc/preinit in subprocess | ||
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2.1 | 18 | * when /etc/preinit is done then it execvp the "real" /sbin/procd |
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1.1 | 19 | |
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4.1 | 20 | procd states: |
| 21 | |||
| 22 | * early (first state): | ||
| 23 | ** coldplug (remount /dev, etc) | ||
| 24 | *** start udevtrigger in subproc | ||
| 25 | *** when udevtrigger completes, hotplug | ||
| 26 | *** when hotplug completes, next state (ubus) | ||
| 27 | * ubus: | ||
| 28 | ** start attempts to connect to ubs | ||
| 29 | ** start ubus as service | ||
| 30 | ** once connection's done then next state (init) | ||
| 31 | * init - read /etc/inittab and run: | ||
| 32 | ** respawn - things that need to keep rerunning once quitted | ||
| 33 | ** askconsole | ||
| 34 | ** askfirst - the "Press Enter to activate this console" message | ||
| 35 | ** sysinit - (usually /etc/init.d/rcS with S) and then next state (running) | ||
| 36 | * running - waits for shutdown signal (usr1/usr2) or reboot (int/term) | ||
| 37 | * shutdown | ||
| 38 | ** runs shutdown command per inittab (also /etc/init.d/rcS but with K) | ||
| 39 | ** when done next state (halt) | ||
| 40 | * halt - kill everything and either enter sleep loop or reboots | ||
| 41 | |||
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5.1 | 42 | |
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| 44 | = Debian = | ||
| 45 | |||
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6.1 | 46 | Needs devtmpfs in kernel. This seem to be first thing that /sbin/init does. (Maybe systemd specific.) |
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5.1 | 47 | |
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6.1 | 48 | {{code}} |
| 49 | mkdir -pv /mnt/debian && mknod /dev/sda b 8 0 && cryptsetup open /dev/sda usb && vgchange -ay vol_grp1 && mount /dev/vol_grp1/logical_vol1 /mnt/debian | ||
| 50 | exec switch_root /mnt/debian /sbin/init | ||
| 51 | {{/code}} | ||
| 52 |