Andrew Morton <a...@linux-foundation.org> writes: > On Mon, 6 Aug 2018 12:39:21 +0200 Geert Uytterhoeven <ge...@linux-m68k.org> > wrote: > >> CC Dan, Michael, AKPM, powerpc >> >> On Mon, Apr 16, 2018 at 3:10 PM Geert Uytterhoeven <ge...@linux-m68k.org> >> wrote: >> > Below is the list of build error/warning regressions/improvements in >> > v4.17-rc1[1] compared to v4.16[2]. >> >> I'd like to point your attention to: >> >> > + warning: vmlinux.o(.text+0x376518): Section mismatch in reference from >> > the function .devm_memremap_pages() to the function >> > .meminit.text:.arch_add_memory(): => N/A >> > + warning: vmlinux.o(.text+0x376d64): Section mismatch in reference from >> > the function .devm_memremap_pages_release() to the function >> > .meminit.text:.arch_remove_memory(): => N/A > > hm. Dan isn't around at present so we're on our own with this one. > > x86 doesn't put arch_add_memory and arch_remove_memory into __meminit. > x86 does > > #ifdef CONFIG_MEMORY_HOTPLUG > int arch_add_memory(int nid, u64 start, u64 size, struct vmem_altmap *altmap, > bool want_memblock) > { > ... > > > So I guess powerpc should do that as well?
But we only recently added it to fix a section mismatch warning: WARNING: vmlinux.o(.text+0x6da88): Section mismatch in reference from the function .arch_add_memory() to the function .meminit.text:.create_section_mapping() The function .arch_add_memory() references the function __meminit .create_section_mapping(). This is often because .arch_add_memory lacks a __meminit annotation or the annotation of .create_section_mapping is wrong. I think the problem is that the section mismatch logic isn't able to cope with __meminit's changing semantics. When CONFIG_MEMORY_HOTPLUG=y references from .text to .meminit.text should be allowed, because they're just folded in together in the linker script. When CONFIG_MEMORY_HOTPLUG=n references from .text to .meminit.text should NOT be allowed, because .meminit.text becomes .init.text and will be freed. I don't see anything in the section mismatch logic to cope with that difference. It looks like __meminit is saving us about 1K on powerpc, so I'm strongly inclined to just remove it entirely from arch/powerpc. Also I haven't been seeing this in my local builds because I have: CONFIG_LD_DEAD_CODE_DATA_ELIMINATION=y So I guess we need to work out why that's interfering with section mismatch analysis. cheers