system: Add support for boot-time mapped devices.

* gnu/build/linux-boot.scm (boot-system): Add #:pre-mount parameter and
  honor it.
* gnu/system/linux-initrd.scm (base-initrd): Add #:mapped-devices
  parameter.  Add 'device-mapping-commands' variable, and use it to
  build the #:pre-mount argument of 'boot-system'.
* gnu/system.scm (mapped-device-user,
  operating-system-user-mapped-devices,
  operating-system-boot-mapped-devices): New procedures.
  (device-mapping-services): Use 'operating-system-user-mapped-devices'
  instead of 'operating-system-mapped-devices'.
  (operating-system-initrd-file): Call the initrd with #:mapped-devices.

linux-initrd: Remove now obsolete #:guile-modules-in-chroot? parameter.

* gnu/build/linux-boot.scm (boot-system): Remove
  #:guile-modules-in-chroot? and related code.
* gnu/system/linux-initrd.scm (base-initrd): Likewise.
* gnu/system/vm.scm (expression->derivation-in-linux-vm): Remove
  #:guile-modules-in-chroot? argument in 'base-initrd' call.

Merge branch 'master' into core-updates

Conflicts:
	gnu/packages/image.scm

system: Add support for Linux-style mapped devices.

* gnu/system/file-systems.scm (<mapped-device>): New record type.
* gnu/system.scm (<operating-system>)[mapped-devices]: New field.
  (luks-device-mapping): New procedure.
  (other-file-system-services)[device-mappings, requirements]: New
  procedures.  Pass #:requirements to 'file-system-service'.
  (device-mapping-services): New procedure.
  (essential-services): Use it.  Append its result to the return value.
  (operating-system-initrd-file): Add comment.
* gnu/services/base.scm (file-system-service): Add #:requirements
  parameter and honor it.
  (device-mapping-service): New procedure.
* gnu/system/linux-initrd.scm (base-initrd): Add comment.

linux-initrd: Store Linux modules in a normal store directory.

* gnu/system/linux-initrd.scm (expression->initrd): Remove #:linux and
  #:linux-modules parameters.  Remove call to
  'float-linux-module-directory'.
  (base-initrd): Add call to 'float-linux-module-directory'.  Use it in
  #:linux-modules argument in the gexp.  Remove #:linux and
  #:linux-modules arguments to 'expression->initrd'.
* gnu/build/linux-initrd.scm (build-initrd): Remove
  #:linux-module-directory parameter.  Don't create 'modules'
  sub-directory.
* gnu/build/linux-boot.scm (boot-system): Mentin that LINUX-MODULES is a
  list of absolute file names.  Don't prepend "/modules/" to
  LINUX-MODULES.
* doc/guix.texi (Initial RAM Disk): Adjust accordingly.

linux-initrd: Remove #:to-copy argument of 'expression->initrd'.

* gnu/system/linux-initrd.scm (expression->initrd): Remove #:to-copy
  parameter.  Remove 'graph-files', and adjust #:references-graphs
  arguments to just list INIT.
  (base-initrd): Remove #:to-copy argument.
* doc/guix.texi (Initial RAM Disk): Adjust accordingly.

linux-initrd: Move initrd creation code to (guix build linux-initrd).

* gnu/build/linux-initrd.scm (cache-compiled-file-name,
  compile-to-cache, build-initrd): New procedures.
* gnu/system/linux-initrd.scm (expression->initrd)[builder]: Remove code
  now moved above.  Use 'build-initrd'.

linux-initrd: Copy all the script's closure to the initrd.

* gnu/system/linux-initrd.scm (expression->initrd): Remove calls to
  'imported-modules' and 'compiled-modules'.  Use 'gexp->script' with
  EXP.  Add the result to TO-COPY.  Make /init a symlink to that script,
  and copy its closure into the "contents" directory.  Add fake
  /proc/self/exe symlink.
* gnu/build/linux-boot.scm (load-linux-module*): Add comment about mmap.
* gnu/system/vm.scm (system-qemu-image/shared-store-script): Add "-m
  256".  This turns out to be needed for initrds containing things like
  e2fsck and several modules; with the default of 128 MiB, loading
  libahci.ko may fail with -1.

Merge branch 'master' into core-updates

linux-initrd: Populate the initrd's store with complete closures.

* gnu/system/linux-initrd.scm (expression->initrd): Add 'graph-files'.
  Use (guix build store-copy) and 'populate-store' instead of local
  hack.  Pass #:references-graphs to 'gexp->derivation'.

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.

Merge branch 'master' into core-updates

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.