On Fri, Jun 18, 2021 at 12:12:28AM +0800, Bin Meng wrote:
When switching to kernel.org x86_64 gcc 11.1.0 toolchain, u-boot.rom built from qemu-x86_defconfig no longer boots anymore. Investigation shows that U-Boot fails at a very early stage during the boot process, in fdtdec_prepare_fdt() where fdt_check_header() complains that there is not a valid device tree found at gd->fdt_blob which points to _end. Now _end points to an allocated section .note.gnu.property which of course is wrong.
This issue is however not seen when using the default Ubuntu 20.04 gnu toolchain (gcc 9.3.0 with binutils 2.34). Further investigation shows that it is caused by a behavior change of binutils v2.36 which is part of the kernel.org gcc 11.1.0 toolchain, via the following commit:
939b95c77bf2 ("Linux/x86: Configure gas with --enable-x86-used-note by default")
In fact, there was already a regression bug report [1] for binutils two months ago, but the binutils folks did not think it is a bug :(
To resolve this, there are several options:
- pass -Wa,-mx86-used-note=no to gas
- pass -R .note.gnu.property to objcopy
- discard the section in the linker script
Linux kernel uses the discard way [2], so let's do the same for U-Boot.
[1] https://sourceware.org/bugzilla/show_bug.cgi?id=27753 [2] commit 4caffe6a28d3 ("x86/vdso: Discard .note.gnu.property sections in vDSO")
Signed-off-by: Bin Meng bmeng.cn@gmail.com
Reviewed-by: Tom Rini trini@konsulko.com