[PATCH v2] x86, realmode: explicitly set entry via command line

From: Nick Desaulniers
Date: Tue Sep 24 2019 - 15:33:16 EST


Linking with ld.lld via $ make LD=ld.lld produces the warning:
ld.lld: warning: cannot find entry symbol _start; defaulting to 0x1000

Linking with ld.bfd shows the default entry is 0x1000:
$ readelf -h arch/x86/realmode/rm/realmode.elf | grep Entry
Entry point address: 0x1000

While ld.lld is being pedantic, just set the entry point explicitly,
instead of depending on the implicit default.

Link: https://github.com/ClangBuiltLinux/linux/issues/216
Signed-off-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
---
Changes V1 -> V2:
* Use command line flag, rather than linker script, as ld.bfd produces a
syntax error for `ENTRY(0x1000)` but is happy with `-e 0x1000`

arch/x86/realmode/rm/Makefile | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/realmode/rm/Makefile b/arch/x86/realmode/rm/Makefile
index f60501a384f9..338a00c5257f 100644
--- a/arch/x86/realmode/rm/Makefile
+++ b/arch/x86/realmode/rm/Makefile
@@ -46,7 +46,7 @@ $(obj)/pasyms.h: $(REALMODE_OBJS) FORCE
targets += realmode.lds
$(obj)/realmode.lds: $(obj)/pasyms.h

-LDFLAGS_realmode.elf := -m elf_i386 --emit-relocs -T
+LDFLAGS_realmode.elf := -m elf_i386 --emit-relocs -e 0x1000 -T
CPPFLAGS_realmode.lds += -P -C -I$(objtree)/$(obj)

targets += realmode.elf
--
2.23.0.351.gc4317032e6-goog