>>> On 19.08.12 at 17:01, Andi Kleen <andi@xxxxxxxxxxxxxx> wrote: > On Sun, Aug 19, 2012 at 09:46:04AM +0100, Jan Beulich wrote: >> >>> Andi Kleen <andi@xxxxxxxxxxxxxx> 08/19/12 5:05 AM >>> >> >Work around a LTO gcc problem: when there is no reference to a variable >> >in a module it will be moved to the end of the program. This causes >> >reordering of initcalls which the kernel does not like. >> >Add a dummy reference function to avoid this. The function is >> >deleted by the linker. >> >> This is not even true on x86, not to speak of generally. > > Why is it not true ? > > __initcall is only defined for !MODULE and there __exit discards. __exit, on x86 and perhaps other arches, causes the code to be discarded at runtime only. >> >+#ifdef CONFIG_LTO >> >+/* Work around a LTO gcc problem: when there is no reference to a variable >> >+ * in a module it will be moved to the end of the program. This causes >> >+ * reordering of initcalls which the kernel does not like. >> >+ * Add a dummy reference function to avoid this. The function is >> >+ * deleted by the linker. >> >+ */ >> >+#define LTO_REFERENCE_INITCALL(x) \ >> >+ ; /* yes this is needed */ \ >> >+ static __used __exit void *reference_##x(void) \ >> >> Why not put it into e.g. section .discard.text? That could be expected to be >> discarded by the linker without being arch dependent, as long as all arches >> use DISCARDS in their linker script. > > > That's what __exit does, doesn't it? No - see above. Using .discard.* enforces the discarding at link time. Jan -- To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
