linux-kernel - Re: kbuild: Ctrl-C of parallel kernel build sometimes corrupts .o.cmd files permanently

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Date:   Thu, 3 Jun 2021 14:39:07 +0200
From:   Ingo Molnar <mingo@...nel.org>
To:     Masahiro Yamada <masahiroy@...nel.org>
Cc:     Michal Marek <michal.lkml@...kovi.net>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: kbuild: Ctrl-C of parallel kernel build sometimes corrupts
 .o.cmd files permanently


* Masahiro Yamada <masahiroy@...nel.org> wrote:

> Hmm, I have not observed this.
> 
> My expectation is, it should work like this:
> 
> When scripts/basic/fixdep is interrupted (or fail due to any reason),
> partially written *.o.cmd is left over. So, having incomplete *.o.cmd
> files is expectation.
> 
> When .DELETE_ON_ERROR is specified, GNU Make is supposed to
> automatically delete the target on any error.
> (If it is interrupted, it should exit with code 130)
> 
> On the next invocation of Make, Kbuild will not include .*.o.cmd files
> whose corresponding *.o files do not exist.
> 
> 
> 
> 
> 
> When you got the corrupted drivers/gpu/drm/.drm_blend.o.cmd,
> didn't you see the log
> Deleting file 'drivers/gpu/drm/drm_blend.o' ?
> 
> 
> 
> If it works as I expect, the log should look like follows:
> (I marked  the lines with '<---- Deleting')
> 
> 
> 
>   CC      security/keys/keyctl_pkey.o
>   CC      kernel/sys.o
>   CC      arch/x86/power/hibernate_64.o
> ^Cmake[5]: *** Deleting file 'drivers/video/fbdev/core/fbcmap.o'  <---- Deleting
> make[5]: *** [scripts/Makefile.build:272:
> drivers/video/fbdev/core/fbmon.o] Interrupt
> make[3]: *** [scripts/Makefile.build:272: security/selinux/nlmsgtab.o] Interrupt
> make[2]: *** [scripts/Makefile.build:272: arch/x86/power/cpu.o] Interrupt
> make[2]: *** [scripts/Makefile.build:272:

Interestingly I don't get *any* interruption messages at all:

  CC      drivers/dma/dw/acpi.o
  CC      sound/pci/ice1712/ice1712.o
  CC      drivers/char/ipmi/ipmi_watchdog.o
  CC      fs/overlayfs/export.o
  CC      fs/nls/nls_cp936.o
  CC      drivers/char/ipmi/ipmi_poweroff.o
 ^Ckepler:~/tip> 

The '^C' there - it just stops, make never prints anything for me.

Weird ...

Thanks,

	Ingo