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? -- 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
