Mirror of GNU Guix
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;;; 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
;;; 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 (guix build linux-initrd)
#:use-module (rnrs io ports)
#:use-module (system foreign)
#: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)
#:export (mount-essential-file-systems
;;; 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)
(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 (linux-command-line)
"Return the Linux kernel command line as a list of strings."
(call-with-input-file "/proc/cmdline"
(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)
(unless (file-exists? (scope "dev"))
(mkdir (scope "dev")))
;; Make the device nodes for SCSI disks.
(mknod (scope "dev/sda") 'block-special #o644 (device-number 8 0))
(mknod (scope "dev/sda1") 'block-special #o644 (device-number 8 1))
(mknod (scope "dev/sda2") 'block-special #o644 (device-number 8 2))
;; The virtio (para-virtualized) block devices, as supported by QEMU/KVM.
(mknod (scope "dev/vda") 'block-special #o644 (device-number 252 0))
(mknod (scope "dev/vda1") 'block-special #o644 (device-number 252 1))
(mknod (scope "dev/vda2") 'block-special #o644 (device-number 252 2))
;; 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))
;; 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)))))
;; 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"))
;; 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 ""))
(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))
(unless (file-exists? "/etc")
(mkdir "/etc"))
(call-with-output-file "/etc/resolv.conf"
(lambda (p)
(display "nameserver\n" p)))
(logand (network-interface-flags sock interface) IFF_UP)))
(define (mount-qemu-smb-share share mount-point)
Vanilla QEMU's `-smb' option just exports a /qemu share, whereas our
`qemu-with-multiple-smb-shares' package exports the /xchg and /store shares
(the latter allows the store to be shared between the host and guest.)"
(format #t "mounting QEMU's SMB share `~a'...\n" share)
(let ((server ""))
(mount (string-append "//" server share) mount-point "cifs" 0
(string->pointer "guest,sec=none"))))
(define (mount-qemu-9p source mount-point)
"Mount QEMU's 9p file system from SOURCE at MOUNT-POINT.
This uses the 'virtio' transport, which requires the various virtio Linux
modules to be loaded."
(format #t "mounting QEMU's 9p share '~a'...\n" source)
(let ((server ""))
(mount source mount-point "9p" 0
(string->pointer "trans=virtio"))))
(define (bind-mount source target)
"Bind-mount SOURCE at TARGET."
(define MS_BIND 4096) ; from libc's <sys/mount.h>
(mount source target "" MS_BIND))
(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* (boot-system #:key
(linux-modules '())
volatile-root? unionfs
(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'.
MOUNTS must be a list of elements of the form:
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 (resolve file)
;; If FILE is a symlink to an absolute file name, resolve it as if we were
;; under /root.
(let ((st (lstat file)))
(if (eq? 'symlink (stat:type st))
(let ((target (readlink file)))
(resolve (string-append "/root" target)))
(define MS_RDONLY 1)
(display "Welcome, this is GNU's early boot Guile.\n")
(display "Use '--repl' for an initrd REPL.\n\n")
(let* ((args (linux-command-line))
(option (lambda (opt)
(let ((opt (string-append opt "=")))
(and=> (find (cut string-prefix? opt <>)
(lambda (arg)
(substring arg (+ 1 (string-index arg #\=))))))))
(to-load (option "--load"))
(root (option "--root")))
(when (member "--repl" args)
(display "loading kernel modules...\n")
(for-each (compose load-linux-module*
(cut string-append "/modules/" <>))
(when qemu-guest-networking?
(unless (configure-qemu-networking)
(display "network interface is DOWN\n")))
;; Make /dev nodes.
;; Prepare the real root file system under /root.
(unless (file-exists? "/root")
(mkdir "/root"))
(if root
(catch #t
(lambda ()
(if volatile-root?
(mkdir-p "/real-root")
(mount root "/real-root" "ext3" 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.
(unless (zero? (system* unionfs "-o"
(error "unionfs failed")))
(mount root "/root" "ext3")))
(lambda args
(format (current-error-port) "exception while mounting '~a': ~s~%"
root args)
(mount "none" "/root" "tmpfs"))
(mount-essential-file-systems #:root "/root")
(unless (file-exists? "/root/dev")
(mkdir "/root/dev")
(make-essential-device-nodes #:root "/root"))
;; Mount the specified file systems.
(for-each (match-lambda
(('cifs source target)
(let ((target (string-append "/root/" target)))
(mkdir-p target)
(mount-qemu-smb-share source target)))
(('9p source target)
(let ((target (string-append "/root/" target)))
(mkdir-p target)
(mount-qemu-9p source target))))
(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
(format #t "loading '~a'...\n" to-load)
(chdir "/root")
(chroot "/root")
;; Obviously this has to be done each time we boot. Do it from here
;; so that statfs(2) returns DEVPTS_SUPER_MAGIC like libc's getpt(3)
;; expects (and thus openpty(3) and its users, such as xterm.)
(mount "none" "/dev/pts" "devpts")
;; TODO: Remove /lib, /share, and /loader.go.
(catch #t
(lambda ()
(primitive-load to-load))
(lambda args
(format (current-error-port) "'~a' raised an exception: ~s~%"
to-load args)
(format (current-error-port)
"boot program '~a' terminated, rebooting~%"
(sleep 2)
(display "no boot file passed via '--load'\n")
(display "entering a warm and cozy REPL\n")
;;; linux-initrd.scm ends here