From 1a7eed303d76764f36eaaec5c6cce26a77b2a47e Mon Sep 17 00:00:00 2001
From: Michael Shigorin <mike@altlinux.org>
Date: Thu, 18 Sep 2014 22:33:19 +0400
Subject: [PATCH] pid1: initial "run as PID 1" feature

This one has been inspired by these guys:

  http://www.informatimago.com/linux/emacs-on-user-mode-linux.html
  https://raymii.org/s/blog/Vim_as_PID_1_Boot_to_Vim.html

It's aimed at building images running their main userspace
piece instead of ramdisk's init, that means PID=1, UID=0.

Mostly fun of course but it suddenly became interesting with
kernel IP autoconfiguration and e.g. elinks running this way
(NB: requires patched make-initrd 0.8.8 at the moment to get
resolver configured).

And startup times are way better than sysvinit and systemd combined!
---
 features.in/pid1/README                       | 15 ++++++++++++++
 features.in/pid1/config.mk                    | 20 +++++++++++++++++++
 .../pid1/stage1/scripts.d/11-initrd-pid1      |  4 ++++
 .../pid1/stage1/scripts.d/82-gzip-initfs      |  3 +++
 features.in/syslinux/cfg.in/20pid1.cfg        |  4 ++++
 5 files changed, 46 insertions(+)
 create mode 100644 features.in/pid1/README
 create mode 100644 features.in/pid1/config.mk
 create mode 100755 features.in/pid1/stage1/scripts.d/11-initrd-pid1
 create mode 100755 features.in/pid1/stage1/scripts.d/82-gzip-initfs
 create mode 100644 features.in/syslinux/cfg.in/20pid1.cfg

diff --git a/features.in/pid1/README b/features.in/pid1/README
new file mode 100644
index 00000000..127962b2
--- /dev/null
+++ b/features.in/pid1/README
@@ -0,0 +1,15 @@
+Эта экспериментальная фича предназначена для обеспечения запуска
+заданного приложения в моно^Wкачестве единственного, т.е. PID 1.
+
+Особенности результата:
+- предельно быстрый запуск;
+- работа под root;
+- отсутствие какой бы то ни было инициализации окружения.
+
+Возможна настройка сетевых интерфейсов средствами ядра, условия:
+- статически собранный модуль для используемого интерфейса;
+- доступность DHCP/BOOTP/RARP в сегменте локальной сети.
+
+Пакет следует добавить в STAGE1_PACKAGES; путь к бинарнику
+задаётся в PID1_BIN; PID1_PANIC позволяет указать время до
+перезагрузки ядра при завершении работы приложения.
diff --git a/features.in/pid1/config.mk b/features.in/pid1/config.mk
new file mode 100644
index 00000000..e4e3cc3b
--- /dev/null
+++ b/features.in/pid1/config.mk
@@ -0,0 +1,20 @@
+# choose the smallest suitable kernel
+use/pid1: sub/stage1 use/syslinux/timeout/1
+	@$(call add_feature)
+	@$(call add,STAGE1_PACKAGES,make-initrd)
+	@$(call add,STAGE2_BOOTARGS,quiet)
+	@$(call add,STAGE2_BOOTARGS,panic=$$(PID1_PANIC))
+	@$(call add,STAGE2_BOOTARGS,rdinit=$$(PID1_BIN))
+	@$(call add,SYSLINUX_CFG,pid1)
+	@$(call try,PID1_PANIC,3)
+	@$(call xport,PID1_PANIC)
+	@$(call xport,PID1_BIN)
+ifeq (i586,$(ARCH))
+	@$(call set,KFLAVOURS,ltsp-client)
+endif
+
+# need a kernel with CONFIG_IP_PNP_DHCP
+# NB: make-initrd must support resolver setup!
+use/pid1/net: use/pid1
+	@$(call add,STAGE2_BOOTARGS,ip=dhcp)
+	@$(call add,STAGE1_PACKAGES,chrooted-resolv)
diff --git a/features.in/pid1/stage1/scripts.d/11-initrd-pid1 b/features.in/pid1/stage1/scripts.d/11-initrd-pid1
new file mode 100755
index 00000000..d3fbd71b
--- /dev/null
+++ b/features.in/pid1/stage1/scripts.d/11-initrd-pid1
@@ -0,0 +1,4 @@
+#!/bin/sh
+# vi's +builtin_terms only cover ansi/xterm
+
+echo "PUT_FILES += /lib/terminfo/l/linux $GLOBAL_PID1_BIN" >> /etc/initrd.mk
diff --git a/features.in/pid1/stage1/scripts.d/82-gzip-initfs b/features.in/pid1/stage1/scripts.d/82-gzip-initfs
new file mode 100755
index 00000000..3f1bc9ec
--- /dev/null
+++ b/features.in/pid1/stage1/scripts.d/82-gzip-initfs
@@ -0,0 +1,3 @@
+#!/bin/sh
+
+gzip < /boot/initrd.img > /boot/full.cz
diff --git a/features.in/syslinux/cfg.in/20pid1.cfg b/features.in/syslinux/cfg.in/20pid1.cfg
new file mode 100644
index 00000000..08c7341a
--- /dev/null
+++ b/features.in/syslinux/cfg.in/20pid1.cfg
@@ -0,0 +1,4 @@
+label pid1
+  menu label ^Just run as PID 1
+  kernel alt0/vmlinuz
+  append initrd=alt0/full.cz @bootargs@