On Tue, Feb 19, 2019 at 1:14 PM Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx> wrote: > > On Fri, Feb 15, 2019 at 11:48 PM Alexei Starovoitov > <alexei.starovoitov@xxxxxxxxx> wrote: > > > > On Mon, Feb 11, 2019 at 09:35:59AM -0500, Joel Fernandes (Google) wrote: > > > Introduce in-kernel headers and other artifacts which are made available > > > as an archive through proc (/proc/kheaders.txz file). > > > The extension '.txz' is not used in kernel code. > > > '.tar.xz' is used for 'tarxz-pkg', 'perf-tarxz-src-pkg' etc. > > > $ git grep '\.txz' > $ git grep '\.tar\.xz' > Documentation/admin-guide/README.rst: xz -cd linux-4.X.tar.xz | tar xvf - > arch/x86/crypto/camellia-aesni-avx-asm_64.S: * > http://koti.mbnet.fi/axh/crypto/camellia-BSD-1.2.0-aesni1.tar.xz > crypto/testmgr.h: * https://bench.cr.yp.to/supercop/supercop-20170228.tar.xz > crypto/testmgr.h: * https://bench.cr.yp.to/supercop/supercop-20170228.tar.xz > crypto/testmgr.h: * https://bench.cr.yp.to/supercop/supercop-20170228.tar.xz > crypto/testmgr.h: * https://bench.cr.yp.to/supercop/supercop-20170228.tar.xz > crypto/testmgr.h: * https://bench.cr.yp.to/supercop/supercop-20170228.tar.xz > scripts/package/Makefile: @echo ' perf-tarxz-src-pkg - Build > $(perf-tar).tar.xz source tarball' > tools/testing/selftests/gen_kselftest_tar.sh: > ext=".tar.xz" > > > > I prefer '.tar.xz' for consistency. > > > > > > > BTW, have you ever looked at scripts/extract-ikconfig? > > You added IKHD_ST and IKHD_ED > just to mimic kernel/configs.c > > It is currently pointless without the extracting tool, > but you might think it is useful to extract headers > from vmlinux or the module without mounting procfs. > > > > > > > This archive makes > > > it possible to build kernel modules, run eBPF programs, and other > > > tracing programs that need to extend the kernel for tracing purposes > > > without any dependency on the file system having headers and build > > > artifacts. > > > > > > On Android and embedded systems, it is common to switch kernels but not > > > have kernel headers available on the file system. Raw kernel headers > > > also cannot be copied into the filesystem like they can be on other > > > distros, due to licensing and other issues. There's no linux-headers > > > package on Android. Further once a different kernel is booted, any > > > headers stored on the file system will no longer be useful. By storing > > > the headers as a compressed archive within the kernel, we can avoid these > > > issues that have been a hindrance for a long time. > > > > The set looks good to me and since the main use case is building bpf progs > > I can route it via bpf-next tree if there are no objections. > > Masahiro, could you please ack it? > > > Honestly, I was not tracking this thread > since I did not know I was responsible for this. > > > I just started to take a closer look, then immediately got scared. > > This version is not mature enough for the merge. > > > > First of all, this patch cannot be compiled out-of-tree (O= option). > > > I do not know why 0-day bot did not catch this apparent breakage. > > > $ make -j8 O=hoge > make[1]: Entering directory '/home/masahiro/workspace/bsp/linux/hoge' > GEN Makefile > Using .. as source for kernel > DESCEND objtool > CALL ../scripts/checksyscalls.sh > CHK include/generated/compile.h > make[2]: *** No rule to make target 'Module.symvers', needed by > 'kernel/kheaders_data.txz'. Stop. > make[2]: *** Waiting for unfinished jobs.... > /home/masahiro/workspace/bsp/linux/Makefile:1043: recipe for target > 'kernel' failed > make[1]: *** [kernel] Error 2 > make[1]: *** Waiting for unfinished jobs.... > make[1]: Leaving directory '/home/masahiro/workspace/bsp/linux/hoge' > Makefile:152: recipe for target 'sub-make' failed > make: *** [sub-make] Error 2 I saw this build error for in-tree building as well. We cannot build this from a pristine source tree. For example, I observed the build error in the following procedure. $ make mrproper $ make defconfig Set CONFIG_IKHEADERS_PROC=y $ make Module.symvers is generated in the modpost stage (the very last stage of build). But, vmlinux depends on kernel/kheaders_data.txz, which includes Module.symvers. So, this is not so simple since it is a circular dependency... -- Best Regards Masahiro Yamada
