machine.conf: generated automatically during ONIE booting

In commit 3cbcb9e, it introduced a new machanism to identify machines
with common CPU module.  The machine.conf was changed to source
other configuration files to calculate the real `onie_machine` and
`onie_platform` at ONIE runtime.

Some NOSes such as SONiC would copy machine.conf to its partition and use
it at its runtime.  The new machine.conf needs other files and has to be
put in /etc directory or it cannot be sourced correctly.

Besides SONiC other NOSes also have similar issues.

The patch intends to expand all variables from machine-build.conf and
machine-live.conf to machine.conf directly.  That would be like the
previous one:

    ONIE:/ # cat /etc/machine.conf
    # /etc/machine.conf for onie

    #  Copyright (C) 2017 Curt Brune <curt@cumulusnetworks.com>
    #  Copyright (C) 2017 david_yang <david_yang@accton.com>
    #
    #  SPDX-License-Identifier:     GPL-2.0

    onie_version=2017.12.12.20-dirty
    onie_vendor_id=259
    onie_build_machine=accton_as7712_32x
    onie_machine_rev=0
    onie_arch=x86_64
    onie_build_platform=x86_64-accton_as7712_32x-r0
    onie_config_version=1
    onie_build_date="2017-12-20T13:43+0800"
    onie_partition_type=gpt
    onie_kernel_version=4.1.38
    onie_firmware=auto
    onie_switch_asic=bcm
    onie_skip_ethmgmt_macs=no
    onie_grub_image_name=grubx64.efi
    onie_machine=accton_as7712_32x
    onie_platform="x86_64-accton_as7712_32x-r0"
    ONIE:/ #

This patch has been tested on Accton AS7712_32X with SONiC environment.

Signed-off-by: Curt Brune <curt@cumulusnetworks.com>

rootconf/default/etc/init.d/gen-config.sh

@@ -1,6 +1,7 @@
 #!/bin/sh
 
 #  Copyright (C) 2017 Curt Brune <curt@cumulusnetworks.com>
+#  Copyright (C) 2017 david_yang <david_yang@accton.com>
 #
 #  SPDX-License-Identifier:     GPL-2.0
 
@@ -17,9 +18,43 @@ gen_live_config()
 
 [ -r /lib/onie/gen-config-platform ] && . /lib/onie/gen-config-platform
 
+gen_machine_config()
+{
+    local build_conf=/etc/machine-build.conf
+    local live_conf=/etc/machine-live.conf
+    local machine_conf=/etc/machine.conf
+
+    gen_live_config > $live_conf
+
+    cat <<EOF > $machine_conf
+# /etc/machine.conf for onie
+
+#  Copyright (C) 2017 Curt Brune <curt@cumulusnetworks.com>
+#  Copyright (C) 2017 david_yang <david_yang@accton.com>
+#
+#  SPDX-License-Identifier:     GPL-2.0
+
+EOF
+
+    cat $build_conf $live_conf >> $machine_conf
+    sed -i -e '/onie_machine=/d' $machine_conf
+    sed -i -e '/onie_platform=/d' $machine_conf
+
+    # Use onie_machine if set, otherwise use build_machine
+    . $build_conf
+    . $live_conf
+    local onie_machine=${onie_machine:-$onie_build_machine}
+    local onie_platform="${onie_arch}-${onie_machine}-r${onie_machine_rev}"
+    cat <<EOF >> $machine_conf
+onie_machine=$onie_machine
+onie_platform="$onie_platform"
+EOF
+
+}
+
 case $cmd in
     start)
-        gen_live_config > /etc/machine-live.conf
+        gen_machine_config
         ;;
     *)