On 22 April 2018 at 11:57, Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx> wrote: > On 22 April 2018 at 11:27, Rafael J. Wysocki <rafael@xxxxxxxxxx> wrote: >> On Thu, Apr 19, 2018 at 6:58 PM, Ard Biesheuvel >> <ard.biesheuvel@xxxxxxxxxx> wrote: >>> When building ACPI bus drivers such as button.ko into the core kernel, >>> other drivers that depend on its symbols are loadable even when booting >>> with ACPI disabled. For instance, nouveau.ko has a link time dependency >>> on acpi_lid_open() on ACPI capable kernels, and calls it regardless of >>> whether the system booted via ACPI. >>> >>> However, when building button.ko as a module, it will refuse to load if >>> the system did not boot in ACPI mode, which subsequently prevents the >>> nouveau driver from loading as well, resulting in broken graphics. >>> >>> Given that returning an error from an initcall() is ignored for drivers >>> that are built into the kernel, >> >> Which makes sense, because they are present in the kernel anyway. >> >>> let's align the module case with this, >>> and not return an error when registering an ACPI bus driver on a system >>> that did not boot via ACPI. >> >> But why is loading a module that's never going to be used actually OK? >> >> Isn't this a problem with the assumptions made by the nouveau driver >> that need not be met depending on what configuration the kernel is run >> in? >> >> Honestly, it doesn't appear quite right to try to change the rest of >> the kernel to follow the nouveau's expectations. >> > > I don't disagree here, I am just unsure whether other options are any better. > > I think the alternative is to make acpi_lid_open() a non-modular > function of the ACPI core that invokes the button ACPI bus driver if > it was loaded, and always returns false otherwise. Would that work for > you? BTW not only nouveau invokes acpi_lid_open(), i915 does it as well. -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
