Rework to allow a read-only rootfs

The diff is unfortunately useless as the build-essential has lost all
formatting, but apart from the usual changes to use different branches,
two new chunks have been added.

Before stage2-gcc there is now stage2-gcc-fixed-headers, which updates
stage1-gcc's internal headers to use limits from system headers.
This was previously done at the beginning of stage2-gcc, but required
changes to the staging area.

There is now also stage2-reset-specs before stage3, which does a nasty
hack to prevent gcc using the sysroot specs in the chroot.

9 files changed, 279 insertions, 300 deletions

diff --git a/base-system-armv7-highbank.morph b/base-system-armv7-highbank.morph
index a317f6a0..37985bc6 100644
--- a/base-system-armv7-highbank.morph
+++ b/base-system-armv7-highbank.morph
@@ -6,16 +6,16 @@ arch: armv7
 strata:
 - morph: build-essential
   repo: baserock:baserock/morphs
-  ref: master
+  ref: baserock/richardmaw/S8564/ro-staging-area
 - morph: core
   repo: baserock:baserock/morphs
-  ref: master
+  ref: baserock/richardmaw/S8564/ro-staging-area
 - morph: foundation
   repo: baserock:baserock/morphs
-  ref: master
+  ref: baserock/richardmaw/S8564/ro-staging-area
 - morph: bsp-armv7-highbank
   repo: baserock:baserock/morphs
-  ref: master
+  ref: baserock/richardmaw/S8564/ro-staging-area
 configuration-extensions:
 - set-hostname
 - ssh
diff --git a/base-system-armv7b-highbank.morph b/base-system-armv7b-highbank.morph
index ce86b415..d6a4141b 100644
--- a/base-system-armv7b-highbank.morph
+++ b/base-system-armv7b-highbank.morph
@@ -6,16 +6,16 @@ arch: armv7b
 strata:
 - morph: build-essential
   repo: baserock:baserock/morphs
-  ref: master
+  ref: baserock/richardmaw/S8564/ro-staging-area
 - morph: core
   repo: baserock:baserock/morphs
-  ref: master
+  ref: baserock/richardmaw/S8564/ro-staging-area
 - morph: foundation
   repo: baserock:baserock/morphs
-  ref: master
+  ref: baserock/richardmaw/S8564/ro-staging-area
 - morph: bsp-armv7b-highbank
   repo: baserock:baserock/morphs
-  ref: master
+  ref: baserock/richardmaw/S8564/ro-staging-area
 configuration-extensions:
 - set-hostname
 - ssh
diff --git a/base-system-x86_64-generic.morph b/base-system-x86_64-generic.morph
index 89e7f397..7950ee3d 100644
--- a/base-system-x86_64-generic.morph
+++ b/base-system-x86_64-generic.morph
@@ -6,16 +6,16 @@ arch: x86_64
 strata:
 - morph: build-essential
   repo: baserock:baserock/morphs
-  ref: master
+  ref: baserock/richardmaw/S8564/ro-staging-area
 - morph: core
   repo: baserock:baserock/morphs
-  ref: master
+  ref: baserock/richardmaw/S8564/ro-staging-area
 - morph: foundation
   repo: baserock:baserock/morphs
-  ref: master
+  ref: baserock/richardmaw/S8564/ro-staging-area
 - morph: bsp-x86_64-generic
   repo: baserock:baserock/morphs
-  ref: master
+  ref: baserock/richardmaw/S8564/ro-staging-area
 configuration-extensions:
 - set-hostname
 - ssh
diff --git a/bsp-armv7-highbank.morph b/bsp-armv7-highbank.morph
index a3eaf2dc..8e23c69e 100644
--- a/bsp-armv7-highbank.morph
+++ b/bsp-armv7-highbank.morph
@@ -3,7 +3,7 @@ description: The platform dependent components required to boot an ARM highbank
 kind: stratum
 build-depends:
 - repo: baserock:baserock/morphs
-  ref: master
+  ref: baserock/richardmaw/S8564/ro-staging-area
   morph: core
 chunks:
 - name: linux
diff --git a/bsp-armv7b-highbank.morph b/bsp-armv7b-highbank.morph
index 0a921f9d..ae41a6a7 100644
--- a/bsp-armv7b-highbank.morph
+++ b/bsp-armv7b-highbank.morph
@@ -3,7 +3,7 @@ description: The platform dependent components required to boot an ARM highbank
 kind: stratum
 build-depends:
 - repo: baserock:baserock/morphs
-  ref: master
+  ref: baserock/richardmaw/S8564/ro-staging-area
   morph: core
 chunks:
 - name: linux
diff --git a/bsp-x86_64-generic.morph b/bsp-x86_64-generic.morph
index 4f2ad85b..58845629 100644
--- a/bsp-x86_64-generic.morph
+++ b/bsp-x86_64-generic.morph
@@ -4,7 +4,7 @@ description: The set of platform specific components required for booting a 64-b
 kind: stratum
 build-depends:
 - repo: baserock:baserock/morphs
-  ref: master
+  ref: baserock/richardmaw/S8564/ro-staging-area
   morph: core
 chunks:
 - name: linux
diff --git a/build-essential.morph b/build-essential.morph
index f4708e3d..4454bdbd 100644
--- a/build-essential.morph
+++ b/build-essential.morph
@@ -1,287 +1,266 @@
 name: build-essential
 description: Toolchain stratum
 kind: stratum
-
 chunks:
-    # Stage 1: build a minimal cross compiler with the host's tools.
-    #
-    # Starting with a cross compiler ensures that (a) nothing from the host
-    # can leak into the build-essential artifacts, and (b) cross-compiling
-    # build-essential is fully tested and supported, since we always use the
-    # cross code paths.
-
-    - name: stage1-binutils
-      repo: upstream:binutils-redhat
-      ref: baserock/build-essential
-      build-mode: bootstrap
-      prefix: /tools
-      build-depends: []
-
-    - name: stage1-gcc
-      repo: upstream:gcc-tarball
-      ref: baserock/build-essential
-      build-mode: bootstrap
-      prefix: /tools
-      build-depends:
-          - stage1-binutils
-
-    # Stage 2: cross-build the whole of build-essential, using the host's tools
-    # but the cross-compiler toolchain.
-    #
-    # Stage 2 GCC outputs code for the same 'bootstrap' machine as stage 1 GCC,
-    # but because stage 2 GCC is also built to *run* on the bootstrap machine
-    # it can only execute inside the stage 3 chroot (due to being built against
-    # a libc with a non-standard prefix).
-
-    - name: stage2-linux-api-headers
-      repo: upstream:linux
-      ref: baserock/build-essential
-      build-mode: bootstrap
-      prefix: /tools
-      build-depends:
-          - stage1-binutils
-          - stage1-gcc
-
-    - name: stage2-eglibc
-      repo: upstream:eglibc2
-      ref: baserock/2.15-build-essential
-      build-mode: bootstrap
-      prefix: /tools
-      build-depends:
-          - stage1-binutils
-          - stage1-gcc
-          - stage2-linux-api-headers
-
-    - name: stage2-binutils
-      repo: upstream:binutils-redhat
-      ref: baserock/build-essential
-      build-mode: bootstrap
-      prefix: /tools
-      build-depends:
-          - stage1-binutils
-          - stage1-gcc
-          - stage2-eglibc
-
-    - name: stage2-gcc
-      repo: upstream:gcc-tarball
-      ref: baserock/build-essential
-      build-mode: bootstrap
-      prefix: /tools
-      build-depends:
-          - stage1-binutils
-          - stage1-gcc
-          - stage2-eglibc
-
-    - name: stage2-busybox
-      repo: upstream:busybox
-      ref: baserock/build-essential
-      build-mode: bootstrap
-      prefix: /tools
-      build-depends:
-          - stage1-binutils
-          - stage1-gcc
-          - stage2-eglibc
-
-    - name: stage2-fhs-dirs
-      repo: baserock:baserock/fhs-dirs
-      ref: master
-      build-mode: bootstrap
-      prefix: /tools
-      build-depends: []
-
-    - name: stage2-gawk
-      repo: upstream:gawk
-      ref: baserock/build-essential
-      build-mode: bootstrap
-      prefix: /tools
-      build-depends:
-          - stage1-binutils
-          - stage1-gcc
-          - stage2-eglibc
-
-    - name: stage2-make
-      repo: upstream:make
-      ref: baserock/build-essential
-      build-mode: bootstrap
-      prefix: /tools
-      build-depends:
-          - stage1-binutils
-          - stage1-gcc
-          - stage2-eglibc
-
-    # Stage 3: build the whole of build-essential again, this time using a
-    # staging area containing only the output of stage 2. The result of this
-    # build is fully reproducible.
-    #
-    # We do a switch-a-roo between stage 2 and 3: stages 2 chunks are all built
-    # to run on a host *-bootstrap-* while stage 3 chunks are native-built for
-    # a *-baserock-* machine. This works, because the cross build was all for
-    # show (and cleanliness) and the binaries actually still run on the host.
-    #
-    # After build-essential is built we do another trick. See
-    # stage2-fhs-dirs.morph for details. Basically, /bin is a symlink to
-    # /tools/bin during stage 2 but in stage 3 it becomes a real directory
-    # again.
-
-    - name: fhs-dirs
-      repo: baserock:baserock/fhs-dirs
-      ref: master
-      build-mode: staging
-      prefix: /usr
-      build-depends:
-          - stage2-binutils
-          - stage2-busybox
-          - stage2-eglibc
-          - stage2-fhs-dirs
-          - stage2-gawk
-          - stage2-gcc
-          - stage2-linux-api-headers
-          - stage2-make
-
-    - name: linux-api-headers
-      repo: upstream:linux
-      ref: baserock/build-essential
-      build-mode: staging
-      prefix: /usr
-      build-depends:
-          - stage2-binutils
-          - stage2-busybox
-          - stage2-eglibc
-          - stage2-fhs-dirs
-          - stage2-gawk
-          - stage2-gcc
-          - stage2-linux-api-headers
-          - stage2-make
-
-    - name: eglibc
-      repo: upstream:eglibc2
-      ref: baserock/2.15-build-essential
-      build-mode: staging
-      prefix: /usr
-      build-depends:
-          - stage2-binutils
-          - stage2-busybox
-          - stage2-eglibc
-          - stage2-fhs-dirs
-          - stage2-gawk
-          - stage2-gcc
-          - stage2-linux-api-headers
-          - stage2-make
-          - linux-api-headers
-
-    - name: zlib
-      repo: upstream:zlib
-      ref: baserock/build-essential
-      build-mode: staging
-      prefix: /usr
-      build-depends:
-          - stage2-binutils
-          - stage2-busybox
-          - stage2-eglibc
-          - stage2-fhs-dirs
-          - stage2-gawk
-          - stage2-gcc
-          - stage2-linux-api-headers
-          - stage2-make
-          - eglibc
-
-    - name: binutils
-      repo: upstream:binutils-redhat
-      ref: baserock/build-essential
-      build-mode: staging
-      prefix: /usr
-      build-depends:
-          - stage2-binutils
-          - stage2-busybox
-          - stage2-eglibc
-          - stage2-fhs-dirs
-          - stage2-gawk
-          - stage2-gcc
-          - stage2-linux-api-headers
-          - stage2-make
-          - eglibc
-          - zlib
-
-    - name: busybox
-      repo: upstream:busybox
-      ref: baserock/build-essential
-      build-mode: staging
-      prefix: /usr
-      build-depends:
-          - stage2-binutils
-          - stage2-busybox
-          - stage2-eglibc
-          - stage2-fhs-dirs
-          - stage2-gawk
-          - stage2-gcc
-          - stage2-linux-api-headers
-          - stage2-make
-          - eglibc
-
-    - name: gawk
-      repo: upstream:gawk
-      ref: baserock/build-essential
-      build-mode: staging
-      prefix: /usr
-      build-depends:
-          - stage2-binutils
-          - stage2-busybox
-          - stage2-eglibc
-          - stage2-fhs-dirs
-          - stage2-gawk
-          - stage2-gcc
-          - stage2-linux-api-headers
-          - stage2-make
-          - eglibc
-
-    - name: gcc
-      repo: upstream:gcc-tarball
-      ref: baserock/build-essential
-      build-mode: staging
-      prefix: /usr
-      build-depends:
-          - stage2-binutils
-          - stage2-busybox
-          - stage2-eglibc
-          - stage2-fhs-dirs
-          - stage2-gawk
-          - stage2-gcc
-          - stage2-linux-api-headers
-          - stage2-make
-          - eglibc
-          - zlib
-
-    - name: make
-      repo: upstream:make
-      ref: baserock/build-essential
-      build-mode: staging
-      prefix: /usr
-      build-depends:
-          - stage2-binutils
-          - stage2-busybox
-          - stage2-eglibc
-          - stage2-fhs-dirs
-          - stage2-gawk
-          - stage2-gcc
-          - stage2-linux-api-headers
-          - stage2-make
-          - eglibc
-
-    # Extras that need to be in build-essential but don't need bootstrapping.
-
-    - name: ccache
-      repo: upstream:ccache
-      ref: baserock/build-essential
-      build-mode: staging
-      prefix: /usr
-      build-depends:
-          - stage2-binutils
-          - stage2-busybox
-          - stage2-eglibc
-          - stage2-fhs-dirs
-          - stage2-gawk
-          - stage2-gcc
-          - stage2-linux-api-headers
-          - stage2-make
-          - eglibc
-          - zlib
+- name: stage1-binutils
+  repo: upstream:binutils-redhat
+  ref: baserock/build-essential
+  build-mode: bootstrap
+  prefix: /tools
+  build-depends: []
+- name: stage1-gcc
+  repo: upstream:gcc-tarball
+  ref: baserock/build-essential
+  build-mode: bootstrap
+  prefix: /tools
+  build-depends:
+  - stage1-binutils
+- name: stage2-linux-api-headers
+  repo: upstream:linux
+  ref: baserock/build-essential
+  build-mode: bootstrap
+  prefix: /tools
+  build-depends:
+  - stage1-binutils
+  - stage1-gcc
+- name: stage2-eglibc
+  repo: upstream:eglibc2
+  ref: baserock/richardmaw/S8564/ro-staging-area
+  build-mode: bootstrap
+  prefix: /tools
+  build-depends:
+  - stage1-binutils
+  - stage1-gcc
+  - stage2-linux-api-headers
+- name: stage2-binutils
+  repo: upstream:binutils-redhat
+  ref: baserock/richardmaw/S8564/ro-staging-area
+  build-mode: bootstrap
+  prefix: /tools
+  build-depends:
+  - stage1-binutils
+  - stage1-gcc
+  - stage2-eglibc
+- name: stage2-gcc-fixed-headers
+  repo: upstream:gcc-tarball
+  ref: baserock/richardmaw/S8564/ro-staging-area
+  build-mode: bootstrap
+  prefix: /tools
+  build-depends:
+  - stage1-binutils
+  - stage1-gcc
+  - stage2-eglibc
+- name: stage2-gcc
+  repo: upstream:gcc-tarball
+  ref: baserock/richardmaw/S8564/ro-staging-area
+  build-mode: bootstrap
+  prefix: /tools
+  build-depends:
+  - stage1-binutils
+  - stage1-gcc
+  - stage2-eglibc
+  - stage2-gcc-fixed-headers
+- name: stage2-busybox
+  repo: upstream:busybox
+  ref: baserock/richardmaw/S8564/ro-staging-area
+  build-mode: bootstrap
+  prefix: /tools
+  build-depends:
+  - stage1-binutils
+  - stage1-gcc
+  - stage2-eglibc
+- name: stage2-fhs-dirs
+  repo: baserock:baserock/fhs-dirs
+  ref: master
+  build-mode: bootstrap
+  prefix: /tools
+  build-depends: []
+- name: stage2-gawk
+  repo: upstream:gawk
+  ref: baserock/richardmaw/S8564/ro-staging-area
+  build-mode: bootstrap
+  prefix: /tools
+  build-depends:
+  - stage1-binutils
+  - stage1-gcc
+  - stage2-eglibc
+- name: stage2-make
+  repo: upstream:make
+  ref: baserock/richardmaw/S8564/ro-staging-area
+  build-mode: bootstrap
+  prefix: /tools
+  build-depends:
+  - stage1-binutils
+  - stage1-gcc
+  - stage2-eglibc
+- name: stage2-reset-specs
+  repo: upstream:eglibc2
+  ref: baserock/richardmaw/S8564/ro-staging-area
+  build-mode: bootstrap
+  prefix: /tools
+  build-depends:
+  - stage1-binutils
+  - stage1-gcc
+  - stage2-linux-api-headers
+  - stage2-eglibc
+- name: fhs-dirs
+  repo: baserock:baserock/fhs-dirs
+  ref: master
+  build-mode: staging
+  prefix: /usr
+  build-depends:
+  - stage2-binutils
+  - stage2-busybox
+  - stage2-eglibc
+  - stage2-fhs-dirs
+  - stage2-gawk
+  - stage2-gcc
+  - stage2-linux-api-headers
+  - stage2-make
+  - stage2-reset-specs
+- name: linux-api-headers
+  repo: upstream:linux
+  ref: baserock/build-essential
+  build-mode: staging
+  prefix: /usr
+  build-depends:
+  - stage2-binutils
+  - stage2-busybox
+  - stage2-eglibc
+  - stage2-fhs-dirs
+  - stage2-gawk
+  - stage2-gcc
+  - stage2-linux-api-headers
+  - stage2-make
+  - stage2-reset-specs
+- name: eglibc
+  repo: upstream:eglibc2
+  ref: baserock/2.15-build-essential
+  build-mode: staging
+  prefix: /usr
+  build-depends:
+  - stage2-binutils
+  - stage2-busybox
+  - stage2-eglibc
+  - stage2-fhs-dirs
+  - stage2-gawk
+  - stage2-gcc
+  - stage2-linux-api-headers
+  - stage2-make
+  - stage2-reset-specs
+  - linux-api-headers
+- name: zlib
+  repo: upstream:zlib
+  ref: baserock/build-essential
+  build-mode: staging
+  prefix: /usr
+  build-depends:
+  - stage2-binutils
+  - stage2-busybox
+  - stage2-eglibc
+  - stage2-fhs-dirs
+  - stage2-gawk
+  - stage2-gcc
+  - stage2-linux-api-headers
+  - stage2-make
+  - stage2-reset-specs
+  - eglibc
+- name: binutils
+  repo: upstream:binutils-redhat
+  ref: baserock/build-essential
+  build-mode: staging
+  prefix: /usr
+  build-depends:
+  - stage2-binutils
+  - stage2-busybox
+  - stage2-eglibc
+  - stage2-fhs-dirs
+  - stage2-gawk
+  - stage2-gcc
+  - stage2-linux-api-headers
+  - stage2-make
+  - stage2-reset-specs
+  - eglibc
+  - zlib
+- name: busybox
+  repo: upstream:busybox
+  ref: baserock/build-essential
+  build-mode: staging
+  prefix: /usr
+  build-depends:
+  - stage2-binutils
+  - stage2-busybox
+  - stage2-eglibc
+  - stage2-fhs-dirs
+  - stage2-gawk
+  - stage2-gcc
+  - stage2-linux-api-headers
+  - stage2-make
+  - stage2-reset-specs
+  - eglibc
+- name: gawk
+  repo: upstream:gawk
+  ref: baserock/build-essential
+  build-mode: staging
+  prefix: /usr
+  build-depends:
+  - stage2-binutils
+  - stage2-busybox
+  - stage2-eglibc
+  - stage2-fhs-dirs
+  - stage2-gawk
+  - stage2-gcc
+  - stage2-linux-api-headers
+  - stage2-make
+  - stage2-reset-specs
+  - eglibc
+- name: gcc
+  repo: upstream:gcc-tarball
+  ref: baserock/build-essential
+  build-mode: staging
+  prefix: /usr
+  build-depends:
+  - stage2-binutils
+  - stage2-busybox
+  - stage2-eglibc
+  - stage2-fhs-dirs
+  - stage2-gawk
+  - stage2-gcc
+  - stage2-linux-api-headers
+  - stage2-make
+  - stage2-reset-specs
+  - eglibc
+  - zlib
+- name: make
+  repo: upstream:make
+  ref: baserock/build-essential
+  build-mode: staging
+  prefix: /usr
+  build-depends:
+  - stage2-binutils
+  - stage2-busybox
+  - stage2-eglibc
+  - stage2-fhs-dirs
+  - stage2-gawk
+  - stage2-gcc
+  - stage2-linux-api-headers
+  - stage2-make
+  - stage2-reset-specs
+  - eglibc
+- name: ccache
+  repo: upstream:ccache
+  ref: baserock/build-essential
+  build-mode: staging
+  prefix: /usr
+  build-depends:
+  - stage2-binutils
+  - stage2-busybox
+  - stage2-eglibc
+  - stage2-fhs-dirs
+  - stage2-gawk
+  - stage2-gcc
+  - stage2-linux-api-headers
+  - stage2-make
+  - stage2-reset-specs
+  - eglibc
+  - zlib
diff --git a/core.morph b/core.morph
index 435bd54c..e6cd5eae 100644
--- a/core.morph
+++ b/core.morph
@@ -4,7 +4,7 @@ description: Core components of a Baserock base system that are build tools requ
 kind: stratum
 build-depends:
 - repo: baserock:baserock/morphs
-  ref: master
+  ref: baserock/richardmaw/S8564/ro-staging-area
   morph: build-essential
 chunks:
 - name: cmake
diff --git a/foundation.morph b/foundation.morph
index 329fb35b..c4cc1946 100644
--- a/foundation.morph
+++ b/foundation.morph
@@ -3,7 +3,7 @@ kind: stratum
 description: Basic userland runtime system
 build-depends:
 - repo: baserock:baserock/morphs
-  ref: master
+  ref: baserock/richardmaw/S8564/ro-staging-area
   morph: core
 chunks:
 - name: attr