In order to fetch the correct entry point with the ISA bit included, for
use by non-ELF boot loaders, parse the output of `objdump -f' for the
start address recorded in the kernel executable itself, rather than
using `nm' to get the value of the `kernel_entry' symbol.
Sign-extend the address retrieved if 32-bit, so that execution is
correctly started on 64-bit processors as well. The tool always prints
the entry point using either 8 or 16 hexadecimal digits, matching the
address width (aka class) of the ELF file, even in the presence of
leading zeros.
Signed-off-by: Maciej W. Rozycki <macro@xxxxxxxxxx>
---
Ralf,
As you requested, here's v2 rebased as a replacement for 5fc9484f5e41,
with the heading reused.
Please apply.
Maciej
---
arch/mips/Makefile | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
linux-mips-start-address.diff
Index: linux-sfr-usead/arch/mips/Makefile
===================================================================
--- linux-sfr-usead.orig/arch/mips/Makefile 2017-08-21 20:48:38.000000000 +0100
+++ linux-sfr-usead/arch/mips/Makefile 2017-08-21 17:47:16.802753000 +0100
@@ -243,8 +243,12 @@ include arch/mips/Kbuild.platforms
ifdef CONFIG_PHYSICAL_START
load-y = $(CONFIG_PHYSICAL_START)
endif
-entry-y = 0x$(shell $(NM) vmlinux 2>/dev/null \
- | grep "\bkernel_entry\b" | cut -f1 -d \ )
+
+# Sign-extend the entry point to 64 bits if retrieved as a 32-bit number.
+entry-y = $(shell $(OBJDUMP) -f vmlinux 2>/dev/null \
+ | sed -n '/^start address / { \
+ s/^.*0x\([0-7].......\)$$/0x00000000\1/; \
+ s/^.*0x\(........\)$$/0xffffffff\1/; p }')
cflags-y += -I$(srctree)/arch/mips/include/asm/mach-generic
drivers-$(CONFIG_PCI) += arch/mips/pci/
