Compile kernel from source error (pie?)

[skulko]

I tried to compile kernel from source following the tutorial ("Optional: Compiling a Kernel from Source"). However it always fails with errors like these: MODPOST vmlinux.o ld: arch/arm64/kernel/head.o: relocation R_AARCH64_ABS32 against_kernel_offset_le_lo32' can not be used when making a shared object ld: init/main.o: relocation R_AARCH64_ABS32 against __crc_system_state' can not be used when making a shared object ld: init/version.o: relocation R_AARCH64_ABS32 againstcrc_init_uts_ns' can not be used when making a shared object ld: init/do_mounts.o: relocation R_AARCH64_ABS32 against `crc_name_to_dev_t' can not be used when making a shared object ld: init/init_task.o: relocation R_AARCH64_ABS32 against `__crc_init_task' can not be used when making a shared object

.....

efistubsort.c:(.initksymtab+sort+0x0): dangerous relocation: unsupported relocation efistubsort.c:(.initksymtab+sort+0x8): dangerous relocation: unsupported relocation ld: warning: creating a DT_TEXTREL in a shared object. make: *** [Makefile:1010: vmlinux] Error 1`

I read that PIE might be the problem... but system should be pie compatible?! I have tried different versions 4.9.y, 4.14.y, 4.16.y, all with the same result..

[sakaki-]

If you are running the 1.2.0 release of the gentoo-on-rpi3-64bit image (or have upgraded to same) then yes, your system uses a 17.0 profile , which has the pie flag set by default for gcc. Which gcc version are you using (please post the output of gcc-config --list-profiles)? I have switched (back) to using the 6.4.0 version for kernel compilation on arm64, as I've found the 7.x variants too unstable.

[skulko]

@sakaki- : yes I got the 1.2.0 release and gcc was downgraded to gcc 6.4.0(-r1) when I did echo "sys-devel/gcc -~arm64" >> /etc/portage/package.accept_keywords/gcc I had to compile it locally (not from the binhost) due to use flag mismatch.. but now I am using gcc-6.4.0-r1. It is also working well for other packages from the repository. Only kernel and net-libs/nodejs (which freezes terminal and makes it impossible to login via ssh) are making trouble so far...

[skulko]

dev-libs/elfutils was missing when I ran emerge =raspberrypi-sources-4.14.9999 but I get the same errors as before: ... can not be used when making a shared object ... dangerous relocation: unsupported relocation ld: warning: creating a DT_TEXTREL in a shared object. make: *** [Makefile:1010: vmlinux] Error 1

[sakaki-]

I normally build arm64 kernels using crossdev on my PC, but I'll have a look at the build process natively on the RPi3 next week to see if I can reproduce this.

[sakaki-]

I have reproduced this error now with a local-only build. It doesn't happen on a crossdev-only build (same compiler, same USE flags), so possibly something to do with binutils or similar, rather than gcc per se. Investigating.

[sakaki-]

Yep, binutils - please see https://forums.gentoo.org/viewtopic-p-8199952.html#8199952

[skulko]

Thanks a lot for your investigating!

[sakaki-]

To recap, the "dangerous relocation" problem is a known issue with the version of binutils shipped on the image (2.30). It is fixed upstream in a later binutils release (upstream patch included in 2.30-r2); and (if using gcc-6.4.0 or gcc-6.4.0-r1) the prior version of binutils (2.29.1-r1) also works. So, to compile a kernel locally on your RPi3, you can either:

• use gcc-6.4.0-r1 and binutils-2.29.1-r1 (see my instructions here); or
• use gcc-7.3.0-r1 and binutils-2.30-r2; to do so, start from a fresh copy of the image, then run genup (as root) which will update your gcc and binutils to these versions, and then perform your normal kernel build steps (make distclean etc.) as described here (but ignore the steps before the sentence "Now, suppose you wish to build the most modern version of the 4.14.y kernel...")

Apologies for the inconvenience, closing this issue as I believe it is fixed now (and the documentation has been modified to recommend stable binutils as well as stable gcc, which should be a safe default for most users, particularly those who want to use distcc).

Please feel free to reopen if still not working for you. Best, sakaki