procd

了解 OpenWRT / Procd

更新記錄

item	note
20170331	第一版

Procd

openwrt-procd
在OpenWrt規劃下，procd主要取代busybox(initd,klogd,syslogd,watchdog)等功能
Init Scripts
procd的init脚本]
舊的OpenWrt採用iniscript，新的改為採用procd
openwrt深入学习笔记.pdf
原生的Linux内核默认启动的第一个用户空间进程是/sbin/init
Openwrt将其修改为默认启动的第一个用户空间进程为/etc/preinit

procd-2015-10-29.1

產生檔案如下

-rwxr-xr-x  1 root root  12K Apr  8  2016 askfirst
-rwxr-xr-x  1 root root  55K Apr  8  2016 init
-rwxr-xr-x  1 root root 255K Apr  8  2016 procd
-rwxr-xr-x  1 root root 8.7K Apr  8  2016 libsetlbf.so
-rwxr-xr-x  1 root root  19K Apr  8  2016 udevtrigger

procd

procd帶參數說明如下：
-s Path to ubus socket
-h run as hotplug daemon
-d Enable debug messages

procd main

procd

init

init
由init會帶出下到兩個程序
- /sbin/procd -H /etc/hotplug-preinit.json
- /bin/sh /etc/preinit

/etc/hotplug-preinit.json

root@OpenWrt:/etc# cat /etc/hotplug-preinit.json 
[
        [ "case", "ACTION", {
                "add": [
                        [ "if",
                                [ "has", "FIRMWARE" ],
                                [
                                        [ "exec", "/sbin/hotplug-call", "%SUBSYSTEM%" ],
                                        [ "load-firmware", "/lib/firmware" ],
                                        [ "return" ]
                                ]
                        ],
                ],
        }, ],
        [ "if",
                [ "and",
                        [ "eq", "SUBSYSTEM", "button" ],
                ],
                [ "exec", "/etc/rc.button/failsafe" ]
        ],
]

/etc/preinit

root@OpenWrt:/etc# cat preinit 
#!/bin/sh
# Copyright (C) 2006 OpenWrt.org
# Copyright (C) 2010 Vertical Communications

[ -z "$PREINIT" ] && exec /sbin/init

export PATH=/usr/sbin:/usr/bin:/sbin:/bin

pi_ifname=
pi_ip=192.168.1.1
pi_broadcast=192.168.1.255
pi_netmask=255.255.255.0

fs_failsafe_ifname=
fs_failsafe_ip=192.168.1.1
fs_failsafe_broadcast=192.168.1.255
fs_failsafe_netmask=255.255.255.0

fs_failsafe_wait_timeout=2

pi_suppress_stderr="y"
pi_init_suppress_stderr="y"
pi_init_path="/usr/sbin:/usr/bin:/sbin:/bin"
pi_init_cmd="/sbin/init"

. /lib/functions.sh
. /lib/functions/preinit.sh
. /lib/functions/system.sh

boot_hook_init preinit_essential
boot_hook_init preinit_main
boot_hook_init failsafe
boot_hook_init initramfs
boot_hook_init preinit_mount_root

for pi_source_file in /lib/preinit/*; do
        . $pi_source_file
done

boot_run_hook preinit_essential

pi_mount_skip_next=false
pi_jffs2_mount_success=false
pi_failsafe_net_message=false

boot_run_hook preinit_main

/lib/preinit/

root@OpenWrt:/etc# ls -l /lib/preinit/
-rw-rw-r--    1 root     root           111 Apr  6 14:58 02_default_set_state
-rw-rw-r--    1 root     root           105 Apr  6 14:58 03_preinit_do_ar71xx.sh
-rw-rw-r--    1 root     root          1102 Apr  6 14:58 05_set_iface_mac_ar71xx
-rw-rw-r--    1 root     root           679 Apr  6 14:58 05_set_preinit_iface_ar71xx
-rw-rw-r--    1 root     root           352 Apr  6 14:58 10_indicate_failsafe
-rw-rw-r--    1 root     root          1033 Apr  6 14:58 10_indicate_preinit
-rw-rw-r--    1 root     root           346 Apr  6 14:58 10_sysinfo
-rw-rw-r--    1 root     root          2400 Apr  6 14:58 30_failsafe_wait
-rw-rw-r--    1 root     root           257 Apr  6 14:58 40_run_failsafe_hook
-rw-rw-r--    1 root     root           254 Apr  6 14:58 50_indicate_regular_preinit
-rw-rw-r--    1 root     root           243 Apr  6 14:58 70_initramfs_test
-rw-rw-r--    1 root     root           316 Apr  6 14:58 80_mount_root
-rw-rw-r--    1 root     root          1178 Apr  6 14:58 82_patch_ath10k
-rw-rw-r--    1 root     root           362 Apr  6 14:58 99_10_failsafe_login
-rw-rw-r--    1 root     root           162 Apr  6 14:58 99_10_run_init

ps
只看到procd，沒有init?

root@OpenWrt:/etc/rc.d# ps
  PID USER       VSZ STAT COMMAND
    1 root      1408 S    /sbin/procd
    2 root         0 SW   [kthreadd]
    3 root         0 SW   [ksoftirqd/0]
    4 root         0 SW   [kworker/0:0]

OpenWRT開機程序

OpenWRT開機程序如下
先執行init，之後是procd

[    2.150000] Freeing unused kernel memory: 252K (80371000 - 803b0000)
[    3.690000] init: Console is alive
[    3.700000] init: - watchdog -
[    5.700000] init: - preinit -
[    6.560000] random: procd urandom read with 10 bits of entropy available
Press the [f] key and hit [enter] to enter failsafe mode
Press the [1], [2], [3] or [4] key and hit [enter] to select the debug level
[   10.020000] jffs2: notice: (328) jffs2_build_xattr_subsystem: complete building xattr subsystem, 0 of xdatum (0 unchecked, 0 orphan) and 0 of xref (0 dead, 0 orphan) found.
[   10.040000] mount_root: switching to jffs2 overlay
[   10.090000] procd: - early -
[   10.100000] procd: - watchdog -
[   11.030000] procd: - ubus -
[   12.040000] procd: - init -
Please press Enter to activate this console.
[   13.140000] NET: Registered protocol family 10
[   13.150000] ip6_tables: (C) 2000-2006 Netfilter Core Team

procd

更新記錄

目錄

Procd

procd-2015-10-29.1

procd

procd main

init

OpenWRT開機程序

參考