Messages in this thread | | | Date | Sun, 19 Aug 2012 17:01:40 +0200 | From | Andi Kleen <> | Subject | Re: [PATCH 55/74] lto, workaround: Add workaround for initcall reordering |
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On Sun, Aug 19, 2012 at 09:46:04AM +0100, Jan Beulich wrote: > >>> Andi Kleen <andi@firstfloor.org> 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.
> > >+#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?
-Andi
-- ak@linux.intel.com -- Speaking for myself only.
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