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 was able to compile it in-tree but it makes the incremental build extremely slow. (Here, the incremental build means "make" without changing any code after the full build.) Before this patch, "make -j8" took 11 sec on my machine. real 0m11.777s user 0m16.608s sys 0m5.164s After this patch, x86_64_defconfig + CONFIG_IKHEADERS_PROC=y takes 53 sec for me since kernel/kheaders_data.txz is regenerated every time even when you did not touch any source file. $ time make -j8 DESCEND objtool CALL scripts/checksyscalls.sh CHK include/generated/compile.h GEN kernel/kheaders_data.txz UPD kernel/kheaders_data.h CC kernel/kheaders.o AR kernel/built-in.a GEN .version CHK include/generated/compile.h UPD include/generated/compile.h CC init/version.o AR init/built-in.a AR built-in.a LD vmlinux.o MODPOST vmlinux.o KSYM .tmp_kallsyms1.o KSYM .tmp_kallsyms2.o LD vmlinux SORTEX vmlinux SYSMAP System.map Building modules, stage 2. CC arch/x86/boot/version.o MODPOST 17 modules VOFFSET arch/x86/boot/compressed/../voffset.h OBJCOPY arch/x86/boot/compressed/vmlinux.bin RELOCS arch/x86/boot/compressed/vmlinux.relocs CC arch/x86/boot/compressed/kaslr.o GZIP arch/x86/boot/compressed/vmlinux.bin.gz CC arch/x86/boot/compressed/misc.o MKPIGGY arch/x86/boot/compressed/piggy.S AS arch/x86/boot/compressed/piggy.o LD arch/x86/boot/compressed/vmlinux ZOFFSET arch/x86/boot/zoffset.h OBJCOPY arch/x86/boot/vmlinux.bin AS arch/x86/boot/header.o LD arch/x86/boot/setup.elf OBJCOPY arch/x86/boot/setup.bin BUILD arch/x86/boot/bzImage Setup is 15612 bytes (padded to 15872 bytes). System is 12673 kB CRC 697aaf88 Kernel: arch/x86/boot/bzImage is ready (#6) real 0m53.024s user 0m32.076s sys 0m9.296s Also, I notice $(ARCH) must be fixed to $(SRCARCH), but that is one of minor issues. We should take time for careful review and test. Please give me more time for thorough review. -- Best Regards Masahiro Yamada
