Re: [PATCH 1/2] init-install.sh: Switch to using static device paths.

[ChenQi <Qi.Chen@windriver.com>]

On 01/13/2015 10:46 PM, Moseley, Drew wrote:
>> On Jan 11, 2015, at 9:05 PM, ChenQi <Qi.Chen@windriver.com> wrote:
>>
>> On 01/09/2015 11:52 PM, Drew Moseley wrote:
>>> Use static device paths for mounting from /dev/disk/<blah> in
>>> case the device ordering changes.
>>>
>>> Signed-off-by: Drew Moseley <drew_moseley@mentor.com>
>>> ---
>>>   meta/recipes-core/initrdscripts/files/init-install.sh | 14 ++++++++++----
>>>   1 file changed, 10 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/meta/recipes-core/initrdscripts/files/init-install.sh b/meta/recipes-core/initrdscripts/files/init-install.sh
>>> index fb537ee..f924418 100644
>>> --- a/meta/recipes-core/initrdscripts/files/init-install.sh
>>> +++ b/meta/recipes-core/initrdscripts/files/init-install.sh
>>> @@ -156,6 +156,12 @@ mkfs.ext3 $rootfs
>>>   echo "Formatting swap partition...($swap)"
>>>   mkswap $swap
>>>   +# Determine the static device paths
>>> +sync; udevadm settle
>>> +bootfs_static="$(udevadm info --query=property --name=$bootfs | grep DEVLINKS= | cut -d= -f2 | cut -d\  -f1)"
>>> +swap_static="$(udevadm info --query=property --name=$swap | grep DEVLINKS= | cut -d= -f2 | cut -d\  -f1)"
>>> +rootfs_uuid="$(udevadm info --query=property --name=$rootfs | grep ID_PART_ENTRY_UUID | cut -d= -f2)"
>>> +
>> Would ID_PART_ENTRY_UUID be always there?
> That's a good question.  In my test systems (two VirtualBox configs and two AMD based PCs) it is always there.  Taking a second look at my developer Ubuntu system it does not seem to have that field so maybe I'm just getting lucky on my test systems.
>
> Anybody have a suggestion for a replacement?

We can use blkid command.

>
>>>   mkdir /tgt_root
>>>   mkdir /src_root
>>>   mkdir -p /boot
>>> @@ -166,8 +172,8 @@ mount -o rw,loop,noatime,nodiratime /run/media/$1/$2 /src_root
>>>   echo "Copying rootfs files..."
>>>   cp -a /src_root/* /tgt_root
>>>   if [ -d /tgt_root/etc/ ] ; then
>>> -    echo "$swap                swap             swap       defaults              0  0" >> /tgt_root/etc/fstab
>>> -    echo "$bootfs              /boot            ext3       defaults              1  2" >> /tgt_root/etc/fstab
>>> +    echo "$swap_static                swap             swap       defaults              0  0" >> /tgt_root/etc/fstab
>>> +    echo "$bootfs_static              /boot            ext3       defaults              1  2" >> /tgt_root/etc/fstab
>>>       # We dont want udev to mount our root device while we're booting...
>>>       if [ -d /tgt_root/etc/udev/ ] ; then
>>>   	echo "/dev/${device}" >> /tgt_root/etc/udev/mount.blacklist
>>> @@ -186,7 +192,7 @@ if [ -f /etc/grub.d/00_header ] ; then
>>>       cat >$GRUBCFG <<_EOF
>>>   menuentry "Linux" {
>>>       set root=(hd0,1)
>>> -    linux /vmlinuz root=$rootfs $rootwait rw $5 $3 $4 quiet
>>> +    linux /vmlinuz root=PARTUUID=$rootfs_uuid $rootwait rw $5 $3 $4 quiet
>> I thought PARTUUID is for GPT only.
>>
> Perhaps so but it does seem to be there on my VirtualBox systems.  My Ubuntu host uses "root=UUID=blah" but that was't working for me at some point.  I'll dig back into it and see what I can find.
>
> Drew
>
>
>
>

root=UUID=xxx has to be resolved by an initramfs because kernel itself 
cannot handle it.

There's a patchset I sent half a year ago trying to solve this problem.
http://cgit.openembedded.org/cgit.cgi/openembedded-core-contrib/log/?h=ChenQi/initramfs-uuid
This offers one solution, maybe an ugly one.

Best Regards,
Chen Qi