On Wed, 15 Jul 2020, Rafael J. Wysocki wrote: > On Wed, Jul 15, 2020 at 5:27 AM Viresh Kumar <[email protected]> wrote: > > > > On 15-07-20, 08:54, Viresh Kumar wrote: > > > On 14-07-20, 22:03, Lee Jones wrote: > > > > On Tue, 14 Jul 2020, Rafael J. Wysocki wrote: > > > > > > > > > On Tue, Jul 14, 2020 at 4:51 PM Lee Jones <[email protected]> > > > > > wrote: > > > > > > > > > > > > Can't see them being used anywhere and the compiler doesn't complain > > > > > > that they're missing, so ... > > > > > > > > > > Aren't they needed for automatic module loading in certain > > > > > configurations? > > > > > > > > Any idea how that works, or where the code is for that? > > > > > > The MODULE_DEVICE_TABLE() thingy creates a map of vendor-id, > > > product-id that the kernel keeps after boot (and so there is no static > > > reference of it for the compiler), later when a device is hotplugged > > > into the kernel it refers to the map to find the related driver for it > > > and loads it if it isn't already loaded. > > > > > > This has some of it, search for MODULE_DEVICE_TABLE() in it. > > > Documentation/driver-api/usb/hotplug.rst > > > > And you just need to add __maybe_unused to them to suppress the > > warning. > > Wouldn't that cause the compiler to optimize them away if it doesn't > see any users?
It looks like they're only unused when !MODULE, in which case optimising them away would be the correct thing to do, no? -- Lee Jones [李琼斯] Senior Technical Lead - Developer Services Linaro.org │ Open source software for Arm SoCs Follow Linaro: Facebook | Twitter | Blog
