I've determined what is going on. The linux headers from http://kernel.ubuntu.com/~kernel-ppa/mainline are built with a gcc 9 version. This causes CONFIG_CC_HAS_ASM_INLINE to be set to true.
However the gcc level that is installed by default on ubuntu 18.04.3 is still gcc 7.4. This level doesn't meet the criteria for supporting CONFIG_CC_HAS_ASM_INLINE, so the building with the linux headers will fail. I manually set the CONFIG_CC_HAS_ASM_INLINE statements false in the linux 5.4 headers (deleted the line in include/generated/autoconf.h and set CONFIG_CC_HAS_ASM_INLINE=n in include/config/auto.conf). With the above set, I was able to build using a gcc 7.4 compiler. So.. either the dependency for the headers needs to include a compatible compiler level, or the headers need to be built to disable those features that are supplied by compilers higher then gcc 7.4. -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1849348 Title: linux 5.4-rc4 Unable to build simple kernel module Status in linux package in Ubuntu: Confirmed Bug description: Cannot build a kernel module, errors in Linux headers using the current RC4 (also tried RC3, and daily) mainline kernel packages from http://kernel.ubuntu.com/~kernel-ppa/mainline Am able to build against a 5.4-rc4 kernel level directly from upstream kernel git repo (on a different platform). To recreate error: Install linux headers, etc from current 5.4 RC. (used 5.4.0-050400rc4 dated 10/20 for this test) --[/tmp/builderr/Makefile]-- EXTRA_CFLAGS += obj-m += conftest.o -- [EOF] -- --[/tmp/builderr/conftest.c]-- #include <linux/module.h> void conftest(void) { } MODULE_LICENSE("GPL-2"); -- [EOF] -- Command: make -C /lib/modules/5.4.0-050400rc4-generic/build M=/tmp/builderr/ V=2 &> make_err.log make.log is attached. Expected output (using above Makefile and conftest.c, performed a build on a system with 4.15.0-66 linux packages installed): -- [expected output] -- make -C /lib/modules/4.15.0-66-generic/build/ M=/tmp/builderr make: Entering directory '/usr/src/linux-headers-4.15.0-66-generic' CC [M] /tmp/builderr/conftest.o Building modules, stage 2. MODPOST 1 modules CC /tmp/builderr/conftest.mod.o LD [M] /tmp/builderr/conftest.ko make: Leaving directory '/usr/src/linux-headers-4.15.0-66-generic' ---- ========= lsb_release -rd Description: Ubuntu 18.04.3 LTS Release: 18.04 uname -a Linux ubuntu_base 5.4.0-050400rc4-generic #201910202130 SMP Sun Oct 20 21:32:54 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux dpkg -l | grep "linux\-[a-z]*\-" ii linux-headers-5.4.0-050400rc4 5.4.0-050400rc4.201910202130 all Header files related to Linux kernel version 5.4.0 ii linux-headers-5.4.0-050400rc4-generic 5.4.0-050400rc4.201910202130 amd64 Linux kernel headers for version 5.4.0 on 64 bit x86 SMP ii linux-image-unsigned-5.4.0-050400rc4-generic 5.4.0-050400rc4.201910202130 amd64 Linux kernel image for version 5.4.0 on 64 bit x86 SMP ri linux-libc-dev:amd64 4.15.0-65.74 amd64 Linux Kernel Headers for development ii linux-modules-5.4.0-050400rc4-generic 5.4.0-050400rc4.201910202130 amd64 Linux kernel extra modules for version 5.4.0 on 64 bit x86 SMP To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1849348/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
