On 07/12/17 17:16, Neil Williams wrote:

On 7 December 2017 at 16:20, Guillaume Tucker <
guillaume.tucker@collabora.com> wrote:

A change was sent a while ago to add support for the Coreboot /
Depthcharge bootloader which is used on Chromebook devices.  This
is useful in particular to avoid having to install U-Boot on
Chromebook devices.  See this Gerrit review here for previous
history:

     https://review.linaro.org/#/c/15203/

I'm now opening this case again to try and get this resolved,
there seem to be several issues with the original patch that
would need to be clarified.  Also, some things might have changed
since then in LAVA or Coreboot which could potentially lead to a
different approach - any feedback on this would be welcome.

Thanks for picking this up.

You're welcome.  I've now uploaded a new version which generates
the command line file but not the FIT image, it expects the
kernel image to be already in this format.  Still the same
Gerrit number:

  https://review.linaro.org/#/c/15203/

I've also made a patch to add the rk3288-veyron-jaq as
a "depthcharge" device type:

  https://review.linaro.org/#/c/22992/

So as a next step, it would be convenient to find a way to have
the FIT image generated as part of the LAVA job with a given
kernel image, dtb, maybe the .its file and optionally a ramdisk.

For the reference:

  http://git.denx.de/?p=u-boot.git;a=blob;f=doc/uImage.FIT/howto.txt;hb=master

To start with, I understand that running mkimage on the
dispatcher is not a valid thing to do, it should receive a
FIT (flattened image tree) kernel image ready to be booted.  This
complicates things a bit for projects like kernelci.org where
only a plain kernel image is built and ramdisks are served
separately, but it's fair enough to say that LAVA is not meant to
be packaging kernel images on the fly.

We've come up with a method in the meantime, although it does mean using
LXC but that makes it completely generic. It's principally designed for
boards which need to munge a kernel and other files into an image to be
transferred to the device using tools like fastboot. This is how KernelCI
will be able to submit boot tests on devices like HiKey and db410c. Sadly,
the example test job is suffering because the db410c devices have a
different problem which is keeping them offline. Matt has been looking into
this.

https://staging.validation.linaro.org/scheduler/job/203317/definition

https://staging.validation.linaro.org/static/docs/v2/actions-deploy.html#index-25

Thanks for the pointers, seems worth investigating.

On the other hand, creating the FIT image is a similar process to
that of uImage, which is currently being done directly on the
dispatcher:

  https://git.linaro.org/lava/lava-dispatcher.git/tree/lava_dispatcher/actions/deploy/prepare.py#n79

So would it make sense to add some code there to support FIT?

Then I believe creating the command line file in LAVA should be
fine, although it probably makes more sense to have both the FIT
image and cmdline file generated by the same build system.  In
any case, both files would need to be served from the dispatcher
TFTP server to the target device running Coreboot / Depthcharge.

That bit is fine, the problem is why this cannot use the existing temporary
paths which all the other TFTP devices use. Is it just to do some mangling
of the files?

This is resolved now with the version I sent yesterday.

So the idea was basically to have an option in Coreboot /
Depthcharge to interactively tell it where to find these files
for the current job to run, say:

     <JOB_NUMBER>/tftp-deploy-<RANDOM>/kernel/vmlinuz
     <JOB_NUMBER>/tftp-deploy-<RANDOM>/kernel/cmdline

It looks like the current patch in Gerrit relies on this location
to be hard-coded in the bootloader, which works fine for a
private development set-up but not for LAVA.

That makes very little sense because the whole point of TFTP is that
everything after the SERVER_IP is just a relative path from the TFTP base
directory which is handled by the TFTP daemon itself.

Ditto.

To recap, my understanding is that the "depthcharge" boot support
code in LAVA would need to:

   * maybe create the cmdline file with basically the kernel
     command line split up with one argument per line

Alternatively, do whatever operations are required in a test shell in the
LXC and then pass those files to the device - entirely within the test
shell support.

That, or maybe run mkimage on the dispatcher like for uImage...

The cmdline file is now generated on the dispatcher.

   * or just download the cmdline file along with the vmlinuz FIT

The ready-made FIT kernel image is now downloaded with the
version I sent yesterday.

   * place both the cmdline and vmlinuz FIT files in the job's
     TFTP directory on the dispatcher

   * turn on the device and open the serial console...

   * interactively pass at least the path to the job TFTP
     directory on the serial console (and if possible the server
     IP address as well, and maybe even the individual file names
     rather than hard-coded vmlinuz and cmdline)

Isn't this equivalent to what U-Boot already does with TFTP?

Almost.  This part is now all implemented in the last patch I
sent.  One thing though is that the NFS rootfs parameters are
stored in the kernel cmdline file and not set interactively in
the bootloader shell.

  The only command sent is to start the tftp
boot with the server IP and the relative paths to the kernel and
cmdline files.

   * look for a bootloader message to know when the kernel starts
     to load and hand over to the next action (login...)

Done as well, I've now got the veyron-jaq device booting fine
with NFS rootfs.  There was an issue with adding a ramdisk to the
FIT image as it was to big to boot on the device, will
investigate this part to add "ramdisk" boot commands.

Please let me know if this sounds reasonable or if we should be
doing anything differently.  I think it would be good to have
some agreement and a clear understanding of how this is going to
be implemented before starting to work on the code again.

Best wishes,
Guillaume