initramfs-framework: create /dev/console

Some kernels, for example linux-yocto 3.19 for qemux86, fail to
execute /init in an initramfs unless there is already a /dev/console
char device in the initramfs. Booting then fails with:
    Kernel panic - not syncing: /dev/console is missing or not a character device!
    Please ensure your rootfs is properly configured

The panic itself comes from a linux-yocto specific patch to
kernel_init_freeable in init/main.c, but even without it, that
function will print an error when /dev/console is missing. The
kernel's Documentation/initrd.txt also mentions creating that device.

It remained unclear why this is not a problem on other machines. On
intel-corei7-64 from meta-intel, something (the kernel?) creates
/dev/console and /dev/[012] before transfering control to the init
script. In that case, creating /dev/console in advance is not
necessary, but does not cause any problem either.

(From OE-Core rev: 0352841cd92f6316bcac092e2fff9d28c352b36b)

Signed-off-by: Patrick Ohly <patrick.ohly@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

1 files changed, 6 insertions, 1 deletions

diff --git a/meta/recipes-core/initrdscripts/initramfs-framework_1.0.bb b/meta/recipes-core/initrdscripts/initramfs-framework_1.0.bb
index 89b900dba9..6c37b9aef6 100644
--- a/meta/recipes-core/initrdscripts/initramfs-framework_1.0.bb
+++ b/meta/recipes-core/initrdscripts/initramfs-framework_1.0.bb
@@ -34,6 +34,11 @@ do_install() {
 
     # debug
     install -m 0755 ${WORKDIR}/debug ${D}/init.d/00-debug
+
+    # Create device nodes expected by some kernels in initramfs
+    # before even executing /init.
+    install -d ${D}/dev
+    mknod -m 622 ${D}/dev/console c 5 1
 }
 
 PACKAGES = "${PN}-base \
@@ -42,7 +47,7 @@ PACKAGES = "${PN}-base \
             initramfs-module-e2fs \
             initramfs-module-debug"
 
-FILES_${PN}-base = "/init /init.d/99-finish"
+FILES_${PN}-base = "/init /init.d/99-finish /dev"
 
 SUMMARY_initramfs-module-mdev = "initramfs support for mdev"
 RDEPENDS_initramfs-module-mdev = "${PN}-base"