diff options
Diffstat (limited to 'gnu/build/linux-boot.scm')
| -rw-r--r-- | gnu/build/linux-boot.scm | 445 |
1 files changed, 445 insertions, 0 deletions
diff --git a/gnu/build/linux-boot.scm b/gnu/build/linux-boot.scm new file mode 100644 index 0000000000..21ee58ad50 --- /dev/null +++ b/gnu/build/linux-boot.scm @@ -0,0 +1,445 @@ +;;; GNU Guix --- Functional package management for GNU +;;; Copyright © 2013, 2014 Ludovic Courtès <ludo@gnu.org> +;;; +;;; This file is part of GNU Guix. +;;; +;;; GNU Guix is free software; you can redistribute it and/or modify it +;;; under the terms of the GNU General Public License as published by +;;; the Free Software Foundation; either version 3 of the License, or (at +;;; your option) any later version. +;;; +;;; GNU Guix is distributed in the hope that it will be useful, but +;;; WITHOUT ANY WARRANTY; without even the implied warranty of +;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +;;; GNU General Public License for more details. +;;; +;;; You should have received a copy of the GNU General Public License +;;; along with GNU Guix. If not, see <http://www.gnu.org/licenses/>. + +(define-module (gnu build linux-boot) + #:use-module (rnrs io ports) + #:use-module (system repl error-handling) + #:autoload (system repl repl) (start-repl) + #:autoload (system base compile) (compile-file) + #:use-module (srfi srfi-1) + #:use-module (srfi srfi-26) + #:use-module (ice-9 match) + #:use-module (ice-9 ftw) + #:use-module (guix build utils) + #:use-module (gnu build file-systems) + #:export (mount-essential-file-systems + linux-command-line + find-long-option + make-essential-device-nodes + configure-qemu-networking + + bind-mount + load-linux-module* + device-number + boot-system)) + +;;; Commentary: +;;; +;;; Utility procedures useful in a Linux initial RAM disk (initrd). Note that +;;; many of these use procedures not yet available in vanilla Guile (`mount', +;;; `load-linux-module', etc.); these are provided by a Guile patch used in +;;; the GNU distribution. +;;; +;;; Code: + +(define* (mount-essential-file-systems #:key (root "/")) + "Mount /proc and /sys under ROOT." + (define (scope dir) + (string-append root + (if (string-suffix? "/" root) + "" + "/") + dir)) + + (unless (file-exists? (scope "proc")) + (mkdir (scope "proc"))) + (mount "none" (scope "proc") "proc") + + (unless (file-exists? (scope "sys")) + (mkdir (scope "sys"))) + (mount "none" (scope "sys") "sysfs")) + +(define (move-essential-file-systems root) + "Move currently mounted essential file systems to ROOT." + (for-each (lambda (dir) + (let ((target (string-append root dir))) + (unless (file-exists? target) + (mkdir target)) + (mount dir target "" MS_MOVE))) + '("/proc" "/sys"))) + +(define (linux-command-line) + "Return the Linux kernel command line as a list of strings." + (string-tokenize + (call-with-input-file "/proc/cmdline" + get-string-all))) + +(define (find-long-option option arguments) + "Find OPTION among ARGUMENTS, where OPTION is something like \"--load\". +Return the value associated with OPTION, or #f on failure." + (let ((opt (string-append option "="))) + (and=> (find (cut string-prefix? opt <>) + arguments) + (lambda (arg) + (substring arg (+ 1 (string-index arg #\=))))))) + +(define* (make-disk-device-nodes base major #:optional (minor 0)) + "Make the block device nodes around BASE (something like \"/root/dev/sda\") +with the given MAJOR number, starting with MINOR." + (mknod base 'block-special #o644 (device-number major minor)) + (let loop ((i 1)) + (when (< i 6) + (mknod (string-append base (number->string i)) + 'block-special #o644 (device-number major (+ minor i))) + (loop (+ i 1))))) + +(define* (make-essential-device-nodes #:key (root "/")) + "Make essential device nodes under ROOT/dev." + ;; The hand-made udev! + + (define (scope dir) + (string-append root + (if (string-suffix? "/" root) + "" + "/") + dir)) + + (unless (file-exists? (scope "dev")) + (mkdir (scope "dev"))) + + ;; Make the device nodes for SCSI disks. + (make-disk-device-nodes (scope "dev/sda") 8) + (make-disk-device-nodes (scope "dev/sdb") 8 16) + (make-disk-device-nodes (scope "dev/sdc") 8 32) + (make-disk-device-nodes (scope "dev/sdd") 8 48) + + ;; SCSI CD-ROM devices (aka. "/dev/sr0" etc.). + (mknod (scope "dev/scd0") 'block-special #o644 (device-number 11 0)) + (mknod (scope "dev/scd1") 'block-special #o644 (device-number 11 1)) + + ;; The virtio (para-virtualized) block devices, as supported by QEMU/KVM. + (make-disk-device-nodes (scope "dev/vda") 252) + + ;; Memory (used by Xorg's VESA driver.) + (mknod (scope "dev/mem") 'char-special #o640 (device-number 1 1)) + (mknod (scope "dev/kmem") 'char-special #o640 (device-number 1 2)) + + ;; Inputs (used by Xorg.) + (unless (file-exists? (scope "dev/input")) + (mkdir (scope "dev/input"))) + (mknod (scope "dev/input/mice") 'char-special #o640 (device-number 13 63)) + (mknod (scope "dev/input/mouse0") 'char-special #o640 (device-number 13 32)) + (mknod (scope "dev/input/event0") 'char-special #o640 (device-number 13 64)) + + ;; System console. This node is magically created by the kernel on the + ;; initrd's root, so don't try to create it in that case. + (unless (string=? root "/") + (mknod (scope "dev/console") 'char-special #o600 + (device-number 5 1))) + + ;; TTYs. + (mknod (scope "dev/tty") 'char-special #o600 + (device-number 5 0)) + (chmod (scope "dev/tty") #o666) + (let loop ((n 0)) + (and (< n 50) + (let ((name (format #f "dev/tty~a" n))) + (mknod (scope name) 'char-special #o600 + (device-number 4 n)) + (loop (+ 1 n))))) + + ;; Serial line. + (mknod (scope "dev/ttyS0") 'char-special #o660 + (device-number 4 64)) + + ;; Pseudo ttys. + (mknod (scope "dev/ptmx") 'char-special #o666 + (device-number 5 2)) + (chmod (scope "dev/ptmx") #o666) + + ;; Create /dev/pts; it will be mounted later, at boot time. + (unless (file-exists? (scope "dev/pts")) + (mkdir (scope "dev/pts"))) + + ;; Rendez-vous point for syslogd. + (mknod (scope "dev/log") 'socket #o666 0) + (mknod (scope "dev/kmsg") 'char-special #o600 (device-number 1 11)) + + ;; Other useful nodes, notably relied on by guix-daemon. + (for-each (match-lambda + ((file major minor) + (mknod (scope file) 'char-special #o666 + (device-number major minor)) + (chmod (scope file) #o666))) + '(("dev/null" 1 3) + ("dev/zero" 1 5) + ("dev/full" 1 7) + ("dev/random" 1 8) + ("dev/urandom" 1 9))) + + (symlink "/proc/self/fd" (scope "dev/fd")) + (symlink "/proc/self/fd/0" (scope "dev/stdin")) + (symlink "/proc/self/fd/1" (scope "dev/stdout")) + (symlink "/proc/self/fd/2" (scope "dev/stderr")) + + ;; Loopback devices. + (let loop ((i 0)) + (when (< i 8) + (mknod (scope (string-append "dev/loop" (number->string i))) + 'block-special #o660 + (device-number 7 i)) + (loop (+ 1 i)))) + + ;; File systems in user space (FUSE). + (mknod (scope "dev/fuse") 'char-special #o666 (device-number 10 229))) + +(define %host-qemu-ipv4-address + (inet-pton AF_INET "10.0.2.10")) + +(define* (configure-qemu-networking #:optional (interface "eth0")) + "Setup the INTERFACE network interface and /etc/resolv.conf according to +QEMU's default networking settings (see net/slirp.c in QEMU for default +networking values.) Return #t if INTERFACE is up, #f otherwise." + (display "configuring QEMU networking...\n") + (let* ((sock (socket AF_INET SOCK_STREAM 0)) + (address (make-socket-address AF_INET %host-qemu-ipv4-address 0)) + (flags (network-interface-flags sock interface))) + (set-network-interface-address sock interface address) + (set-network-interface-flags sock interface (logior flags IFF_UP)) + + ;; Hello! We used to create /etc/resolv.conf here, with "nameserver + ;; 10.0.2.3\n". However, with Linux-libre 3.16, we're getting ENOSPC. + ;; And since it's actually unnecessary, it's gone. + + (logand (network-interface-flags sock interface) IFF_UP))) + +(define (load-linux-module* file) + "Load Linux module from FILE, the name of a `.ko' file." + (define (slurp module) + (call-with-input-file file get-bytevector-all)) + + (load-linux-module (slurp file))) + +(define (device-number major minor) + "Return the device number for the device with MAJOR and MINOR, for use as +the last argument of `mknod'." + (+ (* major 256) minor)) + +(define (pidof program) + "Return the PID of the first presumed instance of PROGRAM." + (let ((program (basename program))) + (find (lambda (pid) + (let ((exe (format #f "/proc/~a/exe" pid))) + (and=> (false-if-exception (readlink exe)) + (compose (cut string=? program <>) basename)))) + (filter-map string->number (scandir "/proc"))))) + +(define* (mount-root-file-system root type + #:key volatile-root? (unionfs "unionfs")) + "Mount the root file system of type TYPE at device ROOT. If VOLATILE-ROOT? +is true, mount ROOT read-only and make it a union with a writable tmpfs using +UNIONFS." + (define (mark-as-not-killable pid) + ;; Tell the 'user-processes' dmd service that PID must be kept alive when + ;; shutting down. + (mkdir-p "/root/etc/dmd") + (let ((port (open-file "/root/etc/dmd/do-not-kill" "a"))) + (chmod port #o600) + (write pid port) + (newline port) + (close-port port))) + + (catch #t + (lambda () + (if volatile-root? + (begin + (mkdir-p "/real-root") + (mount root "/real-root" type MS_RDONLY) + (mkdir-p "/rw-root") + (mount "none" "/rw-root" "tmpfs") + + ;; We want read-write /dev nodes. + (make-essential-device-nodes #:root "/rw-root") + + ;; Make /root a union of the tmpfs and the actual root. Use + ;; 'max_files' to set a high RLIMIT_NOFILE for the unionfs process + ;; itself. Failing to do that, we quickly run out of file + ;; descriptors; see <http://bugs.gnu.org/17827>. + (unless (zero? (system* unionfs "-o" + "cow,allow_other,use_ino,suid,dev,max_files=65536" + "/rw-root=RW:/real-root=RO" + "/root")) + (error "unionfs failed")) + + ;; Make sure unionfs remains alive till the end. Because + ;; 'fuse_daemonize' doesn't tell the PID of the forked daemon, we + ;; have to resort to 'pidof' here. + (mark-as-not-killable (pidof unionfs))) + (begin + (check-file-system root type) + (mount root "/root" type)))) + (lambda args + (format (current-error-port) "exception while mounting '~a': ~s~%" + root args) + (start-repl))) + + (copy-file "/proc/mounts" "/root/etc/mtab")) + +(define (switch-root root) + "Switch to ROOT as the root file system, in a way similar to what +util-linux' switch_root(8) does." + (move-essential-file-systems root) + (chdir root) + + ;; Since we're about to 'rm -rf /', try to make sure we're on an initrd. + ;; TODO: Use 'statfs' to check the fs type, like klibc does. + (when (or (not (file-exists? "/init")) (directory-exists? "/home")) + (format (current-error-port) + "The root file system is probably not an initrd; \ +bailing out.~%root contents: ~s~%" (scandir "/")) + (force-output (current-error-port)) + (exit 1)) + + ;; Delete files from the old root, without crossing mount points (assuming + ;; there are no mount points in sub-directories.) That means we're leaving + ;; the empty ROOT directory behind us, but that's OK. + (let ((root-device (stat:dev (stat "/")))) + (for-each (lambda (file) + (unless (member file '("." "..")) + (let* ((file (string-append "/" file)) + (device (stat:dev (lstat file)))) + (when (= device root-device) + (delete-file-recursively file))))) + (scandir "/"))) + + ;; Make ROOT the new root. + (mount root "/" "" MS_MOVE) + (chroot ".") + (chdir "/") + + (when (file-exists? "/dev/console") + ;; Close the standard file descriptors since they refer to the old + ;; /dev/console, and reopen them. + (let ((console (open-file "/dev/console" "r+b0"))) + (for-each close-fdes '(0 1 2)) + + (dup2 (fileno console) 0) + (dup2 (fileno console) 1) + (dup2 (fileno console) 2) + + (close-port console)))) + + +(define* (boot-system #:key + (linux-modules '()) + qemu-guest-networking? + guile-modules-in-chroot? + volatile-root? + (mounts '())) + "This procedure is meant to be called from an initrd. Boot a system by +first loading LINUX-MODULES, then setting up QEMU guest networking if +QEMU-GUEST-NETWORKING? is true, mounting the file systems specified in MOUNTS, +and finally booting into the new root if any. The initrd supports kernel +command-line options '--load', '--root', and '--repl'. + +Mount the root file system, specified by the '--root' command-line argument, +if any. + +MOUNTS must be a list suitable for 'mount-file-system'. + +When GUILE-MODULES-IN-CHROOT? is true, make core Guile modules available in +the new root. + +When VOLATILE-ROOT? is true, the root file system is writable but any changes +to it are lost." + (define root-mount-point? + (match-lambda + ((device _ "/" _ ...) #t) + (_ #f))) + + (define root-fs-type + (or (any (match-lambda + ((device _ "/" type _ ...) type) + (_ #f)) + mounts) + "ext4")) + + (display "Welcome, this is GNU's early boot Guile.\n") + (display "Use '--repl' for an initrd REPL.\n\n") + + (call-with-error-handling + (lambda () + (mount-essential-file-systems) + (let* ((args (linux-command-line)) + (to-load (find-long-option "--load" args)) + (root (find-long-option "--root" args))) + + (when (member "--repl" args) + (start-repl)) + + (display "loading kernel modules...\n") + (for-each (compose load-linux-module* + (cut string-append "/modules/" <>)) + linux-modules) + + (when qemu-guest-networking? + (unless (configure-qemu-networking) + (display "network interface is DOWN\n"))) + + ;; Make /dev nodes. + (make-essential-device-nodes) + + ;; Prepare the real root file system under /root. + (unless (file-exists? "/root") + (mkdir "/root")) + (if root + (mount-root-file-system (canonicalize-device-spec root) + root-fs-type + #:volatile-root? volatile-root?) + (mount "none" "/root" "tmpfs")) + + (unless (file-exists? "/root/dev") + (mkdir "/root/dev") + (make-essential-device-nodes #:root "/root")) + + ;; Mount the specified file systems. + (for-each mount-file-system + (remove root-mount-point? mounts)) + + (when guile-modules-in-chroot? + ;; Copy the directories that contain .scm and .go files so that the + ;; child process in the chroot can load modules (we would bind-mount + ;; them but for some reason that fails with EINVAL -- XXX). + (mkdir-p "/root/share") + (mkdir-p "/root/lib") + (mount "none" "/root/share" "tmpfs") + (mount "none" "/root/lib" "tmpfs") + (copy-recursively "/share" "/root/share" + #:log (%make-void-port "w")) + (copy-recursively "/lib" "/root/lib" + #:log (%make-void-port "w"))) + + (if to-load + (begin + (switch-root "/root") + (format #t "loading '~a'...\n" to-load) + + ;; TODO: Remove /lib, /share, and /loader.go. + (primitive-load to-load) + + (format (current-error-port) + "boot program '~a' terminated, rebooting~%" + to-load) + (sleep 2) + (reboot)) + (begin + (display "no boot file passed via '--load'\n") + (display "entering a warm and cozy REPL\n") + (start-repl))))))) + +;;; linux-initrd.scm ends here |