[Lkcamp] [PATCH] drm/doc: Adding VKMS module description and use to "Testing and Validation"

[André Almeida]

Hi Gabriela!

On 11/1/19 1:27 AM, Gabriela Bittencourt wrote:
> Add a description on VKMS module and the cases in which it should be used.
> There's a brief explanation on how to set it and use it in a VM, along with
> an example of running an igt-test.
>
> Signed-off-by: Gabriela Bittencourt <gabrielabittencourt00 at gmail.com>
>
> ---
>
> Hi DRM-community,
> this is my first (of many, I hope)  patch in this subsystem. I hope to have
> a lot of learning (and fun :)) working with you guys.
> I'm starting by documenting the VKMS driver in "Userland interfaces", if I
> have been inaccurate in my description or if I misunderstood some concept,
> please let me know.
Cool! It would be nice also to know if you have tested this patch and
checked the output .html file.
> ---
>  Documentation/gpu/drm-uapi.rst | 38 ++++++++++++++++++++++++++++++++++
>  1 file changed, 38 insertions(+)
>
> diff --git a/Documentation/gpu/drm-uapi.rst b/Documentation/gpu/drm-uapi.rst
> index 94f90521f58c..7d6c86b7af76 100644
> --- a/Documentation/gpu/drm-uapi.rst
> +++ b/Documentation/gpu/drm-uapi.rst
> @@ -285,6 +285,44 @@ run-tests.sh is a wrapper around piglit that will execute the tests matching
>  the -t options. A report in HTML format will be available in
>  ./results/html/index.html. Results can be compared with piglit.
>  
> +Using VKMS to test DRM API
> +--------------------------
> +
> +VKMS is a software-only model of a KMS driver that is useful for testing
> +and for running compositors. VKMS aims to enable a virtual display without
> +the need for a hardware display capability. These characteristics made VKMS
> +a perfect tool for validating the DRM core behavior and also support the
> +compositor developer. VKMS helps us to test DRM core function in a virtual
> +machine, which makes it easy to test some of the core changes.
"test DRM core function" ... "test some of the core changes", maybe this
can be reworded to avoid repetition.
> +
> +To Validate changes in DRM API with VKMS, start setting the kernel. The
> +VKMS module is not enabled by defaut, so enable it in the menuconfig::
> +
> +	$ make menuconfig
> +
Not sure if we need to teach people how to enable a module.
> +Compile the kernel with the VKMS enabled and install it in the target
> +machine. VKMS can be run in a Virtual Machine (QEMU, virtme or similar).
> +It's recommended the use of KVM with the minimum of 1GB of RAM and four
> +cores.
> +
> +It's possible to run the IGT-tests in a VM in two ways:
> +1. Use IGT inside a VM
> +2. Use IGT from the host machine and write the results in a shared directory.
> +
> +As follow, there is an example of using a VM with a shared directory with
> +the host machine to run igt-tests. As example it's used virtme::
> +
> +	$ virtme-run --rwdir /path/for/shared_dir --kdir=path/for/kernel/directory --mods=auto
> +
> +Run the igt-tests, as example it's ran the 'kms_flip' tests::
> +
> +	$ /path/for/igt-gpu-tools/scripts/run-tests.sh -p -s -t "kms_flip.*" -v
Should we run this command at the host or guest?
> +
> +In this example instead of build the igt_runner it's used Piglit

I'm feeling that there should be more commas in this sentence. How about
"In this example, instead of building igt_runner, Piglit is used"

> +(-p option); it's created html summary of the tests results and it's saved
> +in the folder "igt-gpu-tools/results"; it's executed only the igt-tests
> +matching the -t option.
> +
>  Display CRC Support
>  -------------------
>  
Thanks,
    André