366 lines
13 KiB
Scheme
366 lines
13 KiB
Scheme
;;; GNU Guix --- Functional package management for GNU
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;;; Copyright © 2013, 2014 Ludovic Courtès <ludo@gnu.org>
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;;;
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;;; This file is part of GNU Guix.
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;;;
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;;; GNU Guix is free software; you can redistribute it and/or modify it
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;;; under the terms of the GNU General Public License as published by
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;;; the Free Software Foundation; either version 3 of the License, or (at
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;;; your option) any later version.
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;;;
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;;; GNU Guix is distributed in the hope that it will be useful, but
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;;; WITHOUT ANY WARRANTY; without even the implied warranty of
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;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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;;; GNU General Public License for more details.
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;;;
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;;; You should have received a copy of the GNU General Public License
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;;; along with GNU Guix. If not, see <http://www.gnu.org/licenses/>.
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(define-module (guix build linux-initrd)
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#:use-module (rnrs io ports)
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#:use-module (system foreign)
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#:autoload (system repl repl) (start-repl)
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#:autoload (system base compile) (compile-file)
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#:use-module (srfi srfi-1)
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#:use-module (srfi srfi-26)
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#:use-module (ice-9 match)
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#:use-module (ice-9 ftw)
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#:use-module (guix build utils)
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#:export (mount-essential-file-systems
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linux-command-line
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make-essential-device-nodes
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configure-qemu-networking
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mount-file-system
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bind-mount
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load-linux-module*
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device-number
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boot-system))
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;;; Commentary:
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;;;
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;;; Utility procedures useful in a Linux initial RAM disk (initrd). Note that
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;;; many of these use procedures not yet available in vanilla Guile (`mount',
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;;; `load-linux-module', etc.); these are provided by a Guile patch used in
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;;; the GNU distribution.
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;;;
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;;; Code:
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(define* (mount-essential-file-systems #:key (root "/"))
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"Mount /proc and /sys under ROOT."
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(define (scope dir)
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(string-append root
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(if (string-suffix? "/" root)
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""
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"/")
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dir))
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(unless (file-exists? (scope "proc"))
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(mkdir (scope "proc")))
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(mount "none" (scope "proc") "proc")
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(unless (file-exists? (scope "sys"))
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(mkdir (scope "sys")))
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(mount "none" (scope "sys") "sysfs"))
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(define (linux-command-line)
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"Return the Linux kernel command line as a list of strings."
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(string-tokenize
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(call-with-input-file "/proc/cmdline"
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get-string-all)))
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(define* (make-essential-device-nodes #:key (root "/"))
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"Make essential device nodes under ROOT/dev."
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;; The hand-made udev!
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(define (scope dir)
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(string-append root
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(if (string-suffix? "/" root)
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""
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"/")
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dir))
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(unless (file-exists? (scope "dev"))
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(mkdir (scope "dev")))
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;; Make the device nodes for SCSI disks.
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(mknod (scope "dev/sda") 'block-special #o644 (device-number 8 0))
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(mknod (scope "dev/sda1") 'block-special #o644 (device-number 8 1))
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(mknod (scope "dev/sda2") 'block-special #o644 (device-number 8 2))
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;; The virtio (para-virtualized) block devices, as supported by QEMU/KVM.
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(mknod (scope "dev/vda") 'block-special #o644 (device-number 252 0))
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(mknod (scope "dev/vda1") 'block-special #o644 (device-number 252 1))
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(mknod (scope "dev/vda2") 'block-special #o644 (device-number 252 2))
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;; Memory (used by Xorg's VESA driver.)
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(mknod (scope "dev/mem") 'char-special #o640 (device-number 1 1))
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(mknod (scope "dev/kmem") 'char-special #o640 (device-number 1 2))
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;; Inputs (used by Xorg.)
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(unless (file-exists? (scope "dev/input"))
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(mkdir (scope "dev/input")))
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(mknod (scope "dev/input/mice") 'char-special #o640 (device-number 13 63))
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(mknod (scope "dev/input/mouse0") 'char-special #o640 (device-number 13 32))
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(mknod (scope "dev/input/event0") 'char-special #o640 (device-number 13 64))
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;; TTYs.
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(mknod (scope "dev/tty") 'char-special #o600
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(device-number 5 0))
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(chmod (scope "dev/tty") #o666)
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(let loop ((n 0))
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(and (< n 50)
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(let ((name (format #f "dev/tty~a" n)))
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(mknod (scope name) 'char-special #o600
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(device-number 4 n))
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(loop (+ 1 n)))))
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;; Pseudo ttys.
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(mknod (scope "dev/ptmx") 'char-special #o666
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(device-number 5 2))
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(chmod (scope "dev/ptmx") #o666)
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;; Create /dev/pts; it will be mounted later, at boot time.
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(unless (file-exists? (scope "dev/pts"))
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(mkdir (scope "dev/pts")))
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;; Rendez-vous point for syslogd.
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(mknod (scope "dev/log") 'socket #o666 0)
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(mknod (scope "dev/kmsg") 'char-special #o600 (device-number 1 11))
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;; Other useful nodes, notably relied on by guix-daemon.
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(for-each (match-lambda
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((file major minor)
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(mknod (scope file) 'char-special #o666
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(device-number major minor))
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(chmod (scope file) #o666)))
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'(("dev/null" 1 3)
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("dev/zero" 1 5)
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("dev/full" 1 7)
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("dev/random" 1 8)
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("dev/urandom" 1 9)))
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(symlink "/proc/self/fd" (scope "dev/fd"))
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(symlink "/proc/self/fd/0" (scope "dev/stdin"))
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(symlink "/proc/self/fd/1" (scope "dev/stdout"))
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(symlink "/proc/self/fd/2" (scope "dev/stderr"))
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;; File systems in user space (FUSE).
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(mknod (scope "dev/fuse") 'char-special #o666 (device-number 10 229)))
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(define %host-qemu-ipv4-address
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(inet-pton AF_INET "10.0.2.10"))
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(define* (configure-qemu-networking #:optional (interface "eth0"))
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"Setup the INTERFACE network interface and /etc/resolv.conf according to
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QEMU's default networking settings (see net/slirp.c in QEMU for default
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networking values.) Return #t if INTERFACE is up, #f otherwise."
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(display "configuring QEMU networking...\n")
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(let* ((sock (socket AF_INET SOCK_STREAM 0))
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(address (make-socket-address AF_INET %host-qemu-ipv4-address 0))
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(flags (network-interface-flags sock interface)))
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(set-network-interface-address sock interface address)
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(set-network-interface-flags sock interface (logior flags IFF_UP))
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(unless (file-exists? "/etc")
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(mkdir "/etc"))
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(call-with-output-file "/etc/resolv.conf"
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(lambda (p)
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(display "nameserver 10.0.2.3\n" p)))
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(logand (network-interface-flags sock interface) IFF_UP)))
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;; Linux mount flags, from libc's <sys/mount.h>.
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(define MS_RDONLY 1)
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(define MS_BIND 4096)
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(define (bind-mount source target)
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"Bind-mount SOURCE at TARGET."
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(mount source target "" MS_BIND))
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(define (load-linux-module* file)
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"Load Linux module from FILE, the name of a `.ko' file."
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(define (slurp module)
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(call-with-input-file file get-bytevector-all))
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(load-linux-module (slurp file)))
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(define (device-number major minor)
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"Return the device number for the device with MAJOR and MINOR, for use as
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the last argument of `mknod'."
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(+ (* major 256) minor))
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(define* (mount-root-file-system root type
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#:key volatile-root? unionfs)
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"Mount the root file system of type TYPE at device ROOT. If VOLATILE-ROOT?
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is true, mount ROOT read-only and make it a union with a writable tmpfs using
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UNIONFS."
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(catch #t
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(lambda ()
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(if volatile-root?
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(begin
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(mkdir-p "/real-root")
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(mount root "/real-root" type MS_RDONLY)
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(mkdir-p "/rw-root")
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(mount "none" "/rw-root" "tmpfs")
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;; We want read-write /dev nodes.
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(make-essential-device-nodes #:root "/rw-root")
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;; Make /root a union of the tmpfs and the actual root.
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(unless (zero? (system* unionfs "-o"
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"cow,allow_other,use_ino,suid,dev"
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"/rw-root=RW:/real-root=RO"
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"/root"))
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(error "unionfs failed")))
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(mount root "/root" "ext3")))
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(lambda args
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(format (current-error-port) "exception while mounting '~a': ~s~%"
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root args)
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(start-repl))))
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(define* (mount-file-system spec #:key (root "/root"))
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"Mount the file system described by SPEC under ROOT. SPEC must have the
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form:
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(DEVICE MOUNT-POINT TYPE (FLAGS ...) OPTIONS)
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DEVICE, MOUNT-POINT, and TYPE must be strings; OPTIONS can be a string or #f;
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FLAGS must be a list of symbols."
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(define flags->bit-mask
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(match-lambda
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(('read-only rest ...)
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(or MS_RDONLY (flags->bit-mask rest)))
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(('bind-mount rest ...)
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(or MS_BIND (flags->bit-mask rest)))
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(()
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0)))
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(match spec
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((source mount-point type (flags ...) options)
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(let ((mount-point (string-append root "/" mount-point)))
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(mkdir-p mount-point)
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(mount source mount-point type (flags->bit-mask flags)
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(if options
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(string->pointer options)
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%null-pointer))))))
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(define* (boot-system #:key
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(linux-modules '())
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qemu-guest-networking?
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guile-modules-in-chroot?
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volatile-root? unionfs
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(root-fs-type "ext3")
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(mounts '()))
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"This procedure is meant to be called from an initrd. Boot a system by
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first loading LINUX-MODULES, then setting up QEMU guest networking if
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QEMU-GUEST-NETWORKING? is true, mounting the file systems specified in MOUNTS,
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and finally booting into the new root if any. The initrd supports kernel
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command-line options '--load', '--root', and '--repl'.
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MOUNTS must be a list suitable for 'mount-file-system'.
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When GUILE-MODULES-IN-CHROOT? is true, make core Guile modules available in
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the new root.
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When VOLATILE-ROOT? is true, the root file system is writable but any changes
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to it are lost."
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(define (resolve file)
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;; If FILE is a symlink to an absolute file name, resolve it as if we were
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;; under /root.
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(let ((st (lstat file)))
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(if (eq? 'symlink (stat:type st))
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(let ((target (readlink file)))
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(resolve (string-append "/root" target)))
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file)))
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(display "Welcome, this is GNU's early boot Guile.\n")
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(display "Use '--repl' for an initrd REPL.\n\n")
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(mount-essential-file-systems)
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(let* ((args (linux-command-line))
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(option (lambda (opt)
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(let ((opt (string-append opt "=")))
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(and=> (find (cut string-prefix? opt <>)
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args)
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(lambda (arg)
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(substring arg (+ 1 (string-index arg #\=))))))))
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(to-load (option "--load"))
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(root (option "--root")))
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(when (member "--repl" args)
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(start-repl))
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(display "loading kernel modules...\n")
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(for-each (compose load-linux-module*
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(cut string-append "/modules/" <>))
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linux-modules)
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(when qemu-guest-networking?
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(unless (configure-qemu-networking)
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(display "network interface is DOWN\n")))
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;; Make /dev nodes.
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(make-essential-device-nodes)
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;; Prepare the real root file system under /root.
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(unless (file-exists? "/root")
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(mkdir "/root"))
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(if root
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(mount-root-file-system root root-fs-type
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#:volatile-root? volatile-root?
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#:unionfs unionfs)
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(mount "none" "/root" "tmpfs"))
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(mount-essential-file-systems #:root "/root")
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(unless (file-exists? "/root/dev")
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(mkdir "/root/dev")
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(make-essential-device-nodes #:root "/root"))
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;; Mount the specified file systems.
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(for-each mount-file-system mounts)
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(when guile-modules-in-chroot?
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;; Copy the directories that contain .scm and .go files so that the
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;; child process in the chroot can load modules (we would bind-mount
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;; them but for some reason that fails with EINVAL -- XXX).
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(mkdir-p "/root/share")
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(mkdir-p "/root/lib")
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(mount "none" "/root/share" "tmpfs")
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(mount "none" "/root/lib" "tmpfs")
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(copy-recursively "/share" "/root/share"
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#:log (%make-void-port "w"))
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(copy-recursively "/lib" "/root/lib"
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#:log (%make-void-port "w")))
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(if to-load
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(begin
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(format #t "loading '~a'...\n" to-load)
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(chdir "/root")
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(chroot "/root")
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;; Obviously this has to be done each time we boot. Do it from here
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;; so that statfs(2) returns DEVPTS_SUPER_MAGIC like libc's getpt(3)
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;; expects (and thus openpty(3) and its users, such as xterm.)
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(mount "none" "/dev/pts" "devpts")
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;; TODO: Remove /lib, /share, and /loader.go.
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(catch #t
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(lambda ()
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(primitive-load to-load))
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(lambda args
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(format (current-error-port) "'~a' raised an exception: ~s~%"
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to-load args)
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(start-repl)))
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(format (current-error-port)
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"boot program '~a' terminated, rebooting~%"
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to-load)
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(sleep 2)
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(reboot))
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(begin
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(display "no boot file passed via '--load'\n")
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(display "entering a warm and cozy REPL\n")
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(start-repl)))))
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;;; linux-initrd.scm ends here
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