michaelh/zephyr
1
0
Fork 0
Code Releases Activity

arch/x86_64: Suppress spurious linker-generated code in the 32 bit stub

Browse source 
Within the past few days, an update to the Ubuntu 18.04 toolchain has
begun emitting code sections during link that are messing with our
stub generation.  They are appearing in the 32 bit stub link despite
not being defined in the single object file, and (worse) being
included in the output segment (i.e. at the start of the bootloader
entry point!) despite not being specifically included by the linker
script.  I don't understand this behavior at all, and it appears to be
directly contrary to the way the linker is documented.

Marc Herbert discovered this was down to gcc being called with
--enable-default-pie, so -no-pie works to suppress this behavior and
restore the default.  And it's correct: we aren't actually generating
a position independent executable, even if we don't understand why the
linker script is being disregarded (to include sections we don't
include).  See discussion in the linked github issue.

Fixes #15877

Signed-off-by: Andy Ross <andrew.j.ross@intel.com>
This commit is contained in:
Andy Ross 2019-05-03 12:33:33 -07:00 • committed by Anas Nashif
commit 9f068737d5
2 changed files with 2 additions and 2 deletions
Download patch file Download diff file Expand all files Collapse all files

2
arch/x86_64/core/CMakeLists.txt
View file

@ -44,7 +44,7 @@ add_custom_command(
-c ${CMAKE_CURRENT_SOURCE_DIR}/xuk-stub32.c
-o ${CMAKE_CURRENT_BINARY_DIR}/xuk-stub32.o
COMMAND ${CMAKE_C_COMPILER} -m32 ${X86_64_BASE_CFLAGS}
-Wl,--build-id=none -nostdlib -nodefaultlibs -nostartfiles
-Wl,--build-id=none -nostdlib -nodefaultlibs -nostartfiles -no-pie
-T ${CMAKE_CURRENT_SOURCE_DIR}/xuk-stub32.ld
${CMAKE_CURRENT_BINARY_DIR}/xuk-stub32.o
-o ${CMAKE_CURRENT_BINARY_DIR}/xuk-stub32.elf

2
arch/x86_64/core/Makefile.xuk
View file

@ -28,7 +28,7 @@ stubs: xuk-stub32.bin xuk-stub16.bin
# image.
xuk-stub32.bin: xuk-stub32.c *.h xuk-stub32.ld
$(CC) -Wall -m32 $(CFLAGS) -c xuk-stub32.c
$(CC) -m32 -T xuk-stub32.ld $(LDFLAGS) -o stub32.elf $(CFLAGS) xuk-stub32.o
$(CC) -m32 -T xuk-stub32.ld $(LDFLAGS) -no-pie -o stub32.elf $(CFLAGS) xuk-stub32.o
$(OBJCOPY) -O binary stub32.elf $@
# This is the main OS image, starting with the 32 bit stub and