Re: [poky] How to override mesa VULKAN_DRIVERS and GALLIUMDRIVERS variables?

Hi Trent,

On 8/4/25 7:19 PM, Trent Piepho via lists.yoctoproject.org wrote:
> [You don't often get email from [email protected]. Learn why this is important at https://aka.ms/LearnAboutSenderIdentification ]
> 
> On Mon, Aug 4, 2025 at 3:15 AM Alexander Kanavin via
> lists.yoctoproject.org <[email protected]>
> wrote:
>>
>> On Sun, 3 Aug 2025 at 08:28, trent.piepho via lists.yoctoproject.org
>> <[email protected]> wrote:
>>> Setting VULKAN_DRIVERS in an bbappend or machine conf file to something like "intel" doesn't work, because the append actions still append to that value all additional drivers.
>>> Trying to remove other drivers with something like VULKAN_DRIVERS:remove = ",amd" doesn't work either, as remove only matches on word boundaries and the list is command delimited, not space delimited.
>>
>> VULKAN_DRIVERS is basically internal to the recipe. You need to set
>> PACKAGECONFIG for mesa to include the needed set:
>>
>> VULKAN_DRIVERS:append = "${@bb.utils.contains('PACKAGECONFIG',
>> 'freedreno', ',freedreno', '', d)}"
> 
> Not sure I follow what you're saying.  If I add the above code inside
> a machine conf file or via bbappend, I'm stuck only adding new drivers

The above code already exists in mesa.inc, Alex was just pointing at the 
implementation and why setting PACKAGECONFIG appropriately would add 
what;s needed to VULKAN_DRIVERS.

> and not able to remove those the recipe has already determined.  While
> it is possible to turn off, e.g., freedreno by PACKAGECONFIG, it can
> be done for neither intel nor amd.
> 

VULKAN_DRIVERS_AMD = "${@bb.utils.contains('PACKAGECONFIG', 'amd', 
',amd', '', d)}"
VULKAN_DRIVERS_INTEL = "${@bb.utils.contains('PACKAGECONFIG', 'intel 
libclc', ',intel', '', d)}"
VULKAN_DRIVERS_LLVM = 
"${VULKAN_DRIVERS_SWRAST}${VULKAN_DRIVERS_AMD}${VULKAN_DRIVERS_ASAHI}${VULKAN_DRIVERS_INTEL}"
VULKAN_DRIVERS:append = "${@bb.utils.contains('PACKAGECONFIG', 
'gallium-llvm', '${VULKAN_DRIVERS_LLVM}', '', d)}"

So in order to have your intel and amd vulkan drivers, you need "amd 
intel libclc gallium-llvm" in PACKAGECONFIG at the very least. Removing 
other should just be a matter of not adding them to PACKAGECONFIG in the 
first place.

If you don't have this code in mesa.inc, this means that you're using an 
older version of OE-Core than current master so it'd be nice to specify 
which one so it's easier for us to help you out, especially since mesa 
has seen a fair amount of changes recently.

> Or are you saying that the mesa recipe should be modified to work
> entirely this way: allowing *all* drivers to be configured via
> PACKAGECONFIG?  Ditto for the GALLIUMDRIVERS configuration, which has
> the same issue.
> 

GALLIUMDRIVERS_AMD = "${@bb.utils.contains('PACKAGECONFIG', 'amd', 
',r300', '', d)}"
GALLIUMDRIVERS_IRIS = "${@bb.utils.contains('PACKAGECONFIG', 'intel 
libclc', ',iris', '', d)}"
GALLIUMDRIVERS_RADEONSI = "${@bb.utils.contains('PACKAGECONFIG', 'amd', 
',radeonsi', '', d)}"
GALLIUMDRIVERS_LLVM = 
"${GALLIUMDRIVERS_LLVMPIPE}${GALLIUMDRIVERS_AMD}${GALLIUMDRIVERS_ASAHI}${GALLIUMDRIVERS_IRIS}${GALLIUMDRIVERS_NOUVEAU}${GALLIUMDRIVERS_RADEONSI}${GALLIUMDRIVERS_SVGA}"
GALLIUMDRIVERS:append = "${@bb.utils.contains('PACKAGECONFIG', 
'gallium-llvm', '${GALLIUMDRIVERS_LLVM}', '', d)}"
PACKAGECONFIG[gallium] = 
"-Dgallium-drivers=${@strip_comma('${GALLIUMDRIVERS}')}, 
-Dgallium-drivers='', libdrm"

So you need "amd intel libclc gallium gallium-llvm" at a minimum in your 
PACKAGECONFIG for this to build properly.

> If the latter, is there a reason to not use `VULKAN_DRIVERS .= "${@…,
> ',driver', '', d)}"`.  It seems like as soon as recipes start to use
> :append internally, they get harder to layer via bbappend and conf
> files.
> 

We could remove the use of :append indeed as this is very likely 
suboptimal in terms of parsing time and doesn't bring much. It's not as 
simple as jsut removing the :append, because of a few :override 
mechanism there but isn't rocker science either. However, I really don't 
think you should be modifying the variables 
(GALLIUMDRIVERS/VULKANDIVRERS) directly. PACKAGECONFIG is there for 
that. If it's not precise enough or is wrong, then it's something we can 
change in the mesa.inc to make sure other people benefit from it instead 
of just keeping some changes in your own layer.

> I did find a workaround to configure the mesa drivers.  In a mesa
> bbappend, set the configure command line arguments directly:
> 
> PACKAGECONFIG[gallium] = "-Dgallium-drivers=iris, -Dgallium-drivers='', libdrm"
> PACKAGECONFIG[vulkan] =
> "-Dvulkan-drivers=intel,-Dvulkan-drivers='',glslang-native
> vulkan-loader vulkan-headers"
> 
> But this unnecessarily duplicates internal code from the recipe that
> will need to be kept in sync.  IMHO, being able to select drivers via
> package config would be a better design.
> 

You should already be able to do that so please help us in helping you 
by telling us your PACKAGECONFIG (in your recipe and returned by 
bitbake-getvar -r mesa PACKAGECONFIG) and OE-Core version you're using. 
Note that this shouldn't be working according to our recipe as intel 
drivers should be requiring libclc. We may have a made a mistake here 
though, but something we could fix with the right amount of information, 
context and testing :)

Cheers,
Quentin