On Wed, Aug 6, 2014 at 3:45 PM, Michal Marek <mmarek@xxxxxxx> wrote: > On 2014-07-26 18:35, Konstantin Khlebnikov wrote: >> This already has been fixed in commit c353acba28fb3fa1fd05fd >> ("kbuild: make: fix if_changed when command contains backslashes") >> but escaping still isn't perfect and triggers false-positive rebuilds. >> >> For x86 problem happens every time, because rules in arch/x86/realmode/rm/ >> and arch/x86/boot/ contains commands like sed -n -e 's/foo\(.*\)/\1/p'. >> Backslash in \1 isn't escaped and turns into ascii symbol with code 1. >> Macro if_changed detects command change and rebuilds target again and again. >> >> Backslash escaping conflicts with other passes because it's used for escaping >> other symbols. To avoid that current macro handles only double backslashes. >> Obviously this doesn't work for \1 like above. >> >> This patch reorders passes. It doubles all backslashes before escaping # and ' >> >> Visible effect in rebuilding x86/defconfig without changes, before patch: >> >> blind@zurg:~/src/linux$ make V=2 >> CHK include/config/kernel.release >> CHK include/generated/uapi/linux/version.h >> CHK include/generated/utsrelease.h >> CALL scripts/checksyscalls.sh - due to target missing >> CHK include/generated/compile.h >> PASYMS arch/x86/realmode/rm/pasyms.h - due to command line change > > With which make and shell version are you seeing this? While the patch > looks correct, I can't reproduce the error here: /bin/sh points to dash (debian default setup). I cannot reproduce this using bash. That explains why this bug is still here. > > $ make V=2 > CHK include/config/kernel.release > CHK include/generated/uapi/linux/version.h > CHK include/generated/utsrelease.h > CALL scripts/checksyscalls.sh - due to target missing > CHK include/generated/compile.h > Kernel: arch/x86/boot/bzImage is ready (#1) > Building modules, stage 2. > MODPOST 12 modules - due to target is PHONY > $ cat arch/x86/realmode/rm/.pasyms.h.cmd > cmd_arch/x86/realmode/rm/pasyms.h := nm arch/x86/realmode/rm/header.o > arch/x86/realmode/rm/trampoline_64.o arch/x86/realmode/rm/stack.o > arch/x86/realmode/rm/reboot.o arch/x86/realmode/rm/wakeup_asm.o > arch/x86/realmode/rm/wakemain.o arch/x86/realmode/rm/video-mode.o > arch/x86/realmode/rm/copy.o arch/x86/realmode/rm/bioscall.o > arch/x86/realmode/rm/regs.o arch/x86/realmode/rm/video-vga.o > arch/x86/realmode/rm/video-vesa.o arch/x86/realmode/rm/video-bios.o | > sed -n -r -e 's/^([0-9a-fA-F]+) [ABCDGRSTVW] (.+)$$/pa_\2 = \2;/p' | > sort | uniq > arch/x86/realmode/rm/pasyms.h > > This is with both 3.16 and my kbuild branch, which is based on 3.16-rc1. > Also, in the description, you say that backslash escaping conflicts with > escaping # and ', but this has nothing to do with the \2 backreference > in the sed command. I'm not quite understand what the difference between escaping standalone backslash ( ' \ ' -> \' \\ \' ) that backreference ( ' \2 ' -> \' \\2 \' ) We have to double backslashes, but this must be done before escaping # and ', otherwise doubling undoes their escaping. > > Michal -- To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html