linux-initrd: Move Linux module tree flattening to another derivation.

* gnu/system/linux-initrd.scm (expression->initrd)[string->regexp]:
  Remove.
  Use 'flat-linux-module-directory'.  Remove the equivalent logic from
  'builder'.
  (flat-linux-module-directory): New procedure.

linux-initrd: Factorize cpio archive creation.

* gnu/build/linux-initrd.scm: New file.
* gnu-system.am (GNU_SYSTEM_MODULES): Add it.
* gnu/system/linux-initrd.scm (expression->initrd): Use (gnu build
  linux-initrd) and 'write-cpio-archive' instead of the inlined code.

Move part of (gnu build linux-boot) to (gnu build file-systems).

* gnu/build/linux-boot.scm (%ext2-endianness, %ext2-sblock-magic,
  %ext2-sblock-creator-os, %ext2-sblock-uuid, %ext2-sblock-volume-name,
  read-ext2-superblock, ext2-superblock-uuid,
  ext2-superblock-volume-name, disk-partitions,
  partition-label-predicate, find-partition-by-label,
  canonicalize-device-spec, MS_RDONLY, MS_NOSUID, MS_NODEV, MS_NOEXEC,
  MS_BIND, MS_MOVE, bind-mount, check-file-system,
  mount-flags->bit-mask, mount-file-system): Move to...
* gnu/build/file-systems.scm: ... here.  New file.
* gnu-system.am (GNU_SYSTEM_MODULES): Add it.
* gnu/services/base.scm: Use (gnu build file-systems).
* gnu/services/dmd.scm (dmd-configuration-file): Likewise.
* gnu/system.scm (operating-system-activation-script): Likewise.
* gnu/system/linux-initrd.scm (base-initrd): Likewise.
* gnu/system/vm.scm (expression->derivation-in-linux-vm): Likewise.

Rename (gnu build linux-initrd) to (gnu build linux-boot).

* gnu/build/linux-initrd.scm: Rename to...
* gnu/build/linux-boot.scm: ... this.
* gnu-system.am (GNU_SYSTEM_MODULES): Adjust accordingly.
* gnu/build/activation.scm, gnu/build/vm.scm, gnu/services/base.scm,
  gnu/services/dmd.scm, gnu/system.scm, gnu/system/linux-initrd.scm,
  gnu/system/vm.scm: Adjust accordingly.

Move operating system helpers from (guix build …) to (gnu build …).

* guix/build/activation.scm, guix/build/install.scm,
  guix/build/linux-initrd.scm, guix/build/vm.scm: Move to...
* gnu/build: ... here.
* Makefile.am (MODULES): Remove the above guix/build/ files.
* gnu-system.am (GNU_SYSTEM_MODULES): Add the above gnu/build/ files
  here.
* gnu/services/base.scm, gnu/services/dmd.scm, gnu/system.scm,
  gnu/system/linux-initrd.scm, gnu/system/vm.scm,
  guix/scripts/system.scm: Adjust to the new module names.

linux-initrd: Load fscache.ko before the 9p modules.

* gnu/system/linux-initrd.scm (base-initrd)[virtio-9p-modules]: Add
  "fscache.ko", required by Linux-libre 3.16.

linux-initrd: Add AHCI modules.

* gnu/system/linux-initrd (linux-modules): Add them.

doc: Add "Initial RAM Disk" section.

* doc/guix.texi (Initial RAM Disk): New node.
* gnu/system/linux-initrd.scm (expression->initrd): Adjust docstring.

linux-initrd: Allow extra modules to be passed to 'base-initrd'.

* gnu/system/linux-initrd.scm (base-initrd): Add #:extra-modules
  parameter.

linux-initrd: Rename 'qemu-initrd' to 'base-initrd'.

* gnu/system/linux-initrd.scm (qemu-initrd): Rename to...
  (base-initrd): ... this.
* gnu/system.scm (<operating-system>)[initrd]: Update accordingly.
* gnu/system/vm.scm (expression->derivation-in-linux-vm,
  system-disk-image, virtualized-operating-system): Likewise.

linux-initrd: Disable QEMU networking by default.

* gnu/system/linux-initrd.scm (qemu-initrd): Remove default value for
  #:qemu-networking?.
* gnu/system/vm.scm (expression->derivation-in-linux-vm): Pass
  #:qemu-networking? #t.
  (system-disk-image): Remove #:qemu-networking? #f.
  (virtualized-operating-system): Pass #:qemu-networking? #t.

linux-initrd: Make the virtio kernel modules optional.

* gnu/system/linux-initrd.scm (qemu-initrd): Add #:virtio? parameter.
  Use it.
* gnu/system/vm.scm (expression->derivation-in-linux-vm): Pass
  'qemu-initrd' #:virtio?.
  (virtualized-operating-system): Likewise.

Merge branch 'master' into core-updates

system: File system sources can be marked as labels or devices.

* gnu/system/file-systems.scm (<file-system>)[title]: New field.
* gnu/services/base.scm (file-system-service): Add #:title parameter.
  In 'start' gexp, use 'canonicalize-device-spec' and honor TITLE.
* gnu/system.scm (other-file-system-services,
  operating-system-root-file-system, operating-system-initrd-file):
  Adjust accordingly.
* gnu/system/linux-initrd.scm (file-system->spec): Likewise.
* gnu/system/vm.scm (system-disk-image): Add 'title' field for the root
  file system.
* guix/build/linux-initrd.scm (mount-file-system): Expect the second
  element of SPEC to be the title.
  (boot-system)[root-mount-point?, root-fs-type]: Likewise.
* gnu/services/dmd.scm (dmd-configuration-file): Select
  'canonicalize-device-spec'.

Merge branch 'master' into core-updates

vm: Disable QEMU networking in the disk image initrd.

* gnu/system/linux-initrd.scm (qemu-initrd): Add #:qemu-networking?
  parameter and honor it.
* gnu/system/vm.scm (system-disk-image): Pass #:qemu-networking #f.

Add (gnu system file-systems).

This fixes a circular dependency between (gnu system) and (gnu system
linux-initrd), where the latter could end up being compiled before
'file-system-type' was defined as a macro.

* gnu/system.scm (<file-system>, %fuse-control-file-system,
  %binary-format-file-system): Move to...
* gnu/system/file-systems.scm: ... here.  New file.
* build-aux/hydra/demo-os.scm, gnu/system/linux-initrd.scm,
  gnu/system/vm.scm: Use it.
* gnu-system.am (GNU_SYSTEM_MODULES): Add it.

linux-initrd: Check the root and other early file systems.

* gnu/system.scm (operating-system-derivation)[boot-file-systems]: Keep "/".
* gnu/system/linux-initrd.scm (file-system->spec): Keep the 'check?'
  flag.
  (qemu-initrd)[helper-packages]: New variable.  Pass it as #:to-copy.
  <gexp>: Add 'set-path-environment-variable' call.  Remove #:unionfs
  argument for 'boot-system'.
* gnu/system/vm.scm (%linux-vm-file-systems): Add 'check?' field/
  (virtualized-operating-system): Likewise for the "9p" file system.
* guix/build/linux-initrd.scm (mount-root-file-system): Change #:unionfs
  default.  Call 'check-file-system' before mounting ROOT, when
  VOLATILE-ROOT? is false.
  (check-file-system): New procedure.
  (mount-file-system): Honor 'check?' element in list; add
  'check-file-system' call.
  (boot-system): Remove #:root-fs-type and #:unionfs parameters.
  [root-mount-point?, root-fs-type]: New variables.
  Call 'mount-file-system' on all MOUNTS but "/".

system: Add first-class file system declarations.

* gnu/system.scm (<operating-system>)[initrd]: Default to
  'qemu-initrd'.
  (<file-system>): New record type.
  (operating-system-root-file-system): New procedure.
  (operating-system-derivation): Take the device name for GRUB from
  'operating-system-root-file-system'.  Pass the
  'operating-system-initrd' procedure the list of boot file systems.
* gnu/system/linux-initrd.scm (file-system->spec): New procedure.
  (qemu-initrd): Add 'file-systems' parameter, and remove #:mounts
  parameter.
  [file-system-type-predicate]: New procedure.
  [linux-modules]: Use it.
  Adjust #:mounts argument in 'boot-system' call.
  (gnu-system-initrd): Remove.
* gnu/system/vm.scm (%linux-vm-file-systems): New variable.
  (expression->derivation-in-linux-vm): Adjust call to 'qemu-initrd'.
  (virtualized-operating-system): New procedure.
  (system-qemu-image/shared-store-script)[initrd]: Remove.  Use
  'virtualized-operating-system'.  Get the 'initrd' file from OS-DRV.
* guix/build/linux-initrd.scm (mount-qemu-smb-share, mount-qemu-9p):
  Remove.
  (MS_RDONLY, MS_BIND): New global variables.
  (bind-mount): Remove local 'MS_BIND' definition.
  (mount-root-file-system): New procedure, with code formerly in
  'boot-system'.
  (mount-file-system): New procedure.
  (boot-system): Add #:root-fs-type parameter.  Remove 'MS_RDONLY' local
  variable.  Use 'mount-root-file-system' and 'mount-file-system'.
* doc/guix.texi (Using the Configuration System): Add 'file-system'
  declaration.

linux-initrd: Rewrite using gexps.

* gnu/system/linux-initrd.scm (expression->initrd): Rename 'inputs'
  parameter to 'to-copy'.  Remove 'files-to-copy'.  Rewrite 'builder' as
  a gexp, and use 'gexp->derivation'.
  (qemu-initrd): Adjust accordingly.