Legato application installation issue

I followed the legato app Installation guide and in the last step when using the update command to install a helloWorld application I got an error that says :

Applying update from file ‘helloWorld.ar758x.update’ to device at address ‘IP addr’.

**ERROR: Unexpected result code from update server.
Update failed
Systems installed:
0 [good] <-- current
Legato framework is running.

The target is configured and I’m able to connect over SSH.
Do you have an idea what can causes this?

Thank you

Hi @Badr,

are you using an ar758x target ?
if so can you give me the legato version you use ?


Hi, Yes I’m using ar758x as target, the legato version is 17.05

Thank you

are you using a read-only target ?

can you grab the update log on target side .
on target: $logread -f
on host pc: $update helloWorld.ar758x.update

Can you send as well $app status output ?


I did what you suggested and in the targed, it says that Legato is R/O. I read that this can be solved by adding something in readonly.adef file do you know how to do that in order to “update” the helloWorld sample

Thank you

Open readonly.sdfef
In apps section, add “$LEGATO_ROOT/apps/sample/helloWorld/helloWorld”

$make clean
$make ar758x

Update your target with the updated cwe.
$fwupdate download <legato.cwe> <target_ip>

then you should see helloworld in app list.


Thank you Vincent,
I have another question about this process. Is it possible to install the helloWorld application in a RW partition on the target other than legato one?

Hi @Badr,

that’s not supported.

Thank you CoRfr.

Otherwise, do you have an example of yocto recipe that include a legato hello world application in the image generated using bitbake ?

I unfortunately do not have such example.
At the moment it would be easier to rely on the legato build system to integrate your application.

So from the yocto point of view, you can do a legato-af_git.bbappend that defines SDEF_TO_USE to point to your own sdef.

In recent versions of Legato (> 17.06 I think), you can include the official sdef to append your application, or you can copy the whole sdef and customize it.