diff options
Diffstat (limited to 'guix/build/linux-initrd.scm')
| -rw-r--r-- | guix/build/linux-initrd.scm | 307 |
1 files changed, 224 insertions, 83 deletions
diff --git a/guix/build/linux-initrd.scm b/guix/build/linux-initrd.scm index 61d4304b65..5be3c1ac2a 100644 --- a/guix/build/linux-initrd.scm +++ b/guix/build/linux-initrd.scm @@ -28,10 +28,11 @@ #:use-module (guix build utils) #:export (mount-essential-file-systems linux-command-line + find-long-option make-essential-device-nodes configure-qemu-networking - mount-qemu-smb-share - mount-qemu-9p + check-file-system + mount-file-system bind-mount load-linux-module* device-number @@ -63,12 +64,30 @@ (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-essential-device-nodes #:key (root "/")) "Make essential device nodes under ROOT/dev." ;; The hand-made udev! @@ -115,6 +134,10 @@ (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)) @@ -143,7 +166,18 @@ (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"))) + (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")) @@ -167,33 +201,13 @@ networking values.) Return #t if INTERFACE is up, #f otherwise." (logand (network-interface-flags sock interface) IFF_UP))) -(define (mount-qemu-smb-share share mount-point) - "Mount QEMU's CIFS/SMB SHARE at 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 "10.0.2.4")) - (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 "10.0.2.4")) - (mount source mount-point "9p" 0 - (string->pointer "trans=virtio")))) +;; Linux mount flags, from libc's <sys/mount.h>. +(define MS_RDONLY 1) +(define MS_BIND 4096) +(define MS_MOVE 8192) (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) @@ -208,6 +222,165 @@ modules to be loaded." 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. + (unless (zero? (system* unionfs "-o" + "cow,allow_other,use_ino,suid,dev" + "/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 (check-file-system device type) + "Run a file system check of TYPE on DEVICE." + (define fsck + (string-append "fsck." type)) + + (let ((status (system* fsck "-v" "-p" device))) + (match (status:exit-val status) + (0 + #t) + (1 + (format (current-error-port) "'~a' corrected errors on ~a; continuing~%" + fsck device)) + (2 + (format (current-error-port) "'~a' corrected errors on ~a; rebooting~%" + fsck device) + (sleep 3) + (reboot)) + (code + (format (current-error-port) "'~a' exited with code ~a on ~a; spawning REPL~%" + fsck code device) + (start-repl))))) + +(define* (mount-file-system spec #:key (root "/root")) + "Mount the file system described by SPEC under ROOT. SPEC must have the +form: + + (DEVICE MOUNT-POINT TYPE (FLAGS ...) OPTIONS CHECK?) + +DEVICE, MOUNT-POINT, and TYPE must be strings; OPTIONS can be a string or #f; +FLAGS must be a list of symbols. CHECK? is a Boolean indicating whether to +run a file system check." + (define flags->bit-mask + (match-lambda + (('read-only rest ...) + (or MS_RDONLY (flags->bit-mask rest))) + (('bind-mount rest ...) + (or MS_BIND (flags->bit-mask rest))) + (() + 0))) + + (match spec + ((source mount-point type (flags ...) options check?) + (let ((mount-point (string-append root "/" mount-point))) + (when check? + (check-file-system source type)) + (mkdir-p mount-point) + (mount source mount-point type (flags->bit-mask flags) + (if options + (string->pointer options) + %null-pointer)) + + ;; Update /etc/mtab. + (mkdir-p (string-append root "/etc")) + (let ((port (open-file (string-append root "/etc/mtab") "a"))) + (format port "~a ~a ~a ~a 0 0~%" + source mount-point type options) + (close-port port)))))) + +(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? @@ -220,9 +393,10 @@ 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: +Mount the root file system, specified by the '--root' command-line argument, +if any. - (FILE-SYSTEM-TYPE SOURCE TARGET) +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. @@ -238,21 +412,25 @@ to it are lost." (resolve (string-append "/root" target))) file))) - (define MS_RDONLY 1) + (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") (mount-essential-file-systems) (let* ((args (linux-command-line)) - (option (lambda (opt) - (let ((opt (string-append opt "="))) - (and=> (find (cut string-prefix? opt <>) - args) - (lambda (arg) - (substring arg (+ 1 (string-index arg #\=)))))))) - (to-load (option "--load")) - (root (option "--root"))) + (to-load (find-long-option "--load" args)) + (root (find-long-option "--root" args))) (when (member "--repl" args) (start-repl)) @@ -273,55 +451,17 @@ to it are lost." (unless (file-exists? "/root") (mkdir "/root")) (if root - (catch #t - (lambda () - (if volatile-root? - (begin - ;; XXX: For lack of a union file system... - (mkdir-p "/real-root") - (mount root "/real-root" "ext3" MS_RDONLY) - (mount "none" "/root" "tmpfs") - - ;; XXX: 'copy-recursively' cannot deal with device nodes, so - ;; explicitly avoid /dev. - (for-each (lambda (file) - (unless (string=? "dev" file) - (copy-recursively (string-append "/real-root/" - file) - (string-append "/root/" - file) - #:log (%make-void-port - "w")))) - (scandir "/real-root" - (lambda (file) - (not (member file '("." "..")))))) - - ;; TODO: Unmount /real-root. - ) - (mount root "/root" "ext3"))) - (lambda args - (format (current-error-port) "exception while mounting '~a': ~s~%" - root args) - (start-repl))) + (mount-root-file-system root root-fs-type + #:volatile-root? volatile-root?) (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)))) - mounts) + (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 @@ -338,9 +478,8 @@ to it are lost." (if to-load (begin + (switch-root "/root") (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) @@ -352,9 +491,11 @@ to it are lost." (lambda () (primitive-load to-load)) (lambda args + (start-repl)) + (lambda args (format (current-error-port) "'~a' raised an exception: ~s~%" to-load args) - (start-repl))) + (display-backtrace (make-stack #t) (current-error-port)))) (format (current-error-port) "boot program '~a' terminated, rebooting~%" to-load) |