[RFC PATCH v2 2/2] openbmc: Use JFFS2 for RW overlay filesystem

[Andrew Jeffery]

We can enable JFFS2 support on mtd6 (the RW mtd partition) with a
(first-pass) kernel patch[1] applied to work-around a 'stutter' in the
(optimised) ARM mmiocpy() implementation.

[1] Unmerged, but tested: https://lists.ozlabs.org/pipermail/openbmc/2016-February/001874.html

Signed-off-by: Andrew Jeffery <andrew at aj.id.au>
---
 meta-phosphor/classes/image-overlay.bbclass                |  7 ++++++-
 .../classes/obmc-phosphor-image_types_uboot.bbclass        | 14 ++++++++++++--
 .../obmc-phosphor-initfs/files/obmc-init.sh                |  2 +-
 .../obmc-phosphor-initfs/files/obmc-update.sh              |  2 +-
 4 files changed, 20 insertions(+), 5 deletions(-)

diff --git a/meta-phosphor/classes/image-overlay.bbclass b/meta-phosphor/classes/image-overlay.bbclass
index 1c6137d..9203955 100644
--- a/meta-phosphor/classes/image-overlay.bbclass
+++ b/meta-phosphor/classes/image-overlay.bbclass
@@ -3,7 +3,12 @@ INITRD_IMAGE ?= "core-image-minimal-initramfs"
 INITRD ?= "${DEPLOY_DIR_IMAGE}/${INITRD_IMAGE}-${MACHINE}.cpio.${INITRD_CTYPE}${uboot}"
 
 IMAGE_BASETYPE ?= "squashfs-xz"
-OVERLAY_BASETYPE ?= "ext4"
+OVERLAY_BASETYPE ?= "jffs2"
+
+# Note: OVERLAY_BASETYPE_OPTS is not used when OVERLAY_BASETYPE=jffs2
+# Options for when OVERLAY_BASETYPE=ext4
+#
+# OVERLAY_BASETYPE_OPTS ?= "-b 4096 -F -O^huge_file"
 
 IMAGE_TYPES_${PN} += "${IMAGE_BASETYPE}"
 
diff --git a/meta-phosphor/classes/obmc-phosphor-image_types_uboot.bbclass b/meta-phosphor/classes/obmc-phosphor-image_types_uboot.bbclass
index c390c36..abbbe75 100644
--- a/meta-phosphor/classes/obmc-phosphor-image_types_uboot.bbclass
+++ b/meta-phosphor/classes/obmc-phosphor-image_types_uboot.bbclass
@@ -51,8 +51,18 @@ do_generate_flash() {
        fi
 
        oe_mkimage  "${initrd}" "${INITRD_CTYPE}" || bbfatal "oe_mkimage initrd"
-       dd if=/dev/zero of=${ddir}/${rwfs} bs=1k count=${RWFS_SIZE}
-       mkfs.${OVERLAY_BASETYPE} -b 4096 -F -O^huge_file ${ddir}/${rwfs} || bbfatal "mkfs rwfs"
+
+       # Set all the bits to effecitvely erase the RW partition on the NOR when
+       # the image is written
+       dd if=/dev/zero bs=1k count=${RWFS_SIZE} \
+              | tr '\000' '\377' > ${ddir}/${rwfs}
+       if [ "${OVERLAY_BASETYPE}" != jffs2 ]; then
+              # jffs2 can mount an erased filesystem as if it were formatted,
+              # so don't bother formatting unless we're configured to use
+              # something different.
+              mkfs.${OVERLAY_BASETYPE} ${OVERLAY_BASETYPE_OPTS} \
+                     ${ddir}/${rwfs} || bbfatal "mkfs rwfs"
+       fi
 
        dst="${ddir}/${FLASH_IMAGE_NAME}"
        rm -rf $dst
diff --git a/meta-phosphor/common/recipes-phosphor/obmc-phosphor-initfs/files/obmc-init.sh b/meta-phosphor/common/recipes-phosphor/obmc-phosphor-initfs/files/obmc-init.sh
index 9674765..f1e448b 100644
--- a/meta-phosphor/common/recipes-phosphor/obmc-phosphor-initfs/files/obmc-init.sh
+++ b/meta-phosphor/common/recipes-phosphor/obmc-phosphor-initfs/files/obmc-init.sh
@@ -72,7 +72,7 @@ rodev=/dev/mtdblock${rofs#mtd}
 rwdev=/dev/mtdblock${rwfs#mtd}
 
 rofst=squashfs
-rwfst=ext4
+rwfst=jffs2
 roopts=ro
 rwopts=rw
 
diff --git a/meta-phosphor/common/recipes-phosphor/obmc-phosphor-initfs/files/obmc-update.sh b/meta-phosphor/common/recipes-phosphor/obmc-phosphor-initfs/files/obmc-update.sh
index face06d..4b08e17 100755
--- a/meta-phosphor/common/recipes-phosphor/obmc-phosphor-initfs/files/obmc-update.sh
+++ b/meta-phosphor/common/recipes-phosphor/obmc-phosphor-initfs/files/obmc-update.sh
@@ -38,7 +38,7 @@ findmtd() {
 rwfs=$(findmtd rwfs)
 
 rwdev=/dev/mtdblock${rwfs#mtd}
-rwfst=ext4
+rwfst=jffs2
 rwopts=rw
 rorwopts=ro${rwopts#rw}
 
-- 
2.5.0