On 2025-03-10 4:45 pm, Aaron Kling wrote:
On Mon, Mar 10, 2025 at 7:42 AM Robin Murphy <robin.murphy@xxxxxxx> wrote:
On 2025-03-10 6:11 am, Aaron Kling via B4 Relay wrote:
From: Aaron Kling <webgeek1234@xxxxxxxxx>
If ARCH_QCOM is enabled when building arm_smmu_v3,
This has nothing to do with SMMUv3, though?
a dependency on
qcom-scm is added, which currently cannot be disabled. Add a prompt to
ARM_SMMU_QCOM to allow disabling this dependency.
Why is that an issue - what problem arises from having the SCM driver
enabled? AFAICS it's also selected by plenty of other drivers including
pretty fundamental ones like pinctrl. If it is somehow important to
exclude the SCM driver, then I can't really imagine what the use-case
would be for building a kernel which won't work on most Qualcomm
platforms but not simply disabling ARCH_QCOM...
I am working with the android kernel. The more recent setup enables a
minimal setup of configs in a core kernel that works across all
supported arch's, then requires further support to all be modules. I
specifically am working with tegra devices. But as ARCH_QCOM is
enabled in the core defconfig, when I build smmuv3 as a module, I end
up with a dependency on qcom-scm which gets built as an additional
module. And it would be preferable to not require qcom modules to boot
a tegra device.
That just proves my point though - if you disable ARM_SMMU_QCOM in that
context then you've got a kernel which won't work properly on Qualcomm
platforms, so you may as well have just disabled ARCH_QCOM anyway. In
fact the latter is objectively better since it then would not break the
fundamental premise of "a core kernel that works across all supported
arch's" :/
Maybe if you can find a viable way to separate out all the arm-smmu-qcom
stuff into its own sub-module which only loads when needed, or possibly
make SCM a soft-dep (given that we already have to cope with it being
loaded but not initialised yet) then that might be a reasonable change
to make; as it stands, I don't think this patch is. And it's definitely
not a stable "fix" either way.
But frankly, weird modules happen. Why the heck is parport_pc currently
loaded on my AArch64 workstation!? I can't even begin to imagine, but
I'll live...
Thanks,
Robin.
