Re: [PATCH] Don't mkdir -p include/config in the sourcetree when using O=outputdir option

[John Kacur]

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On Wed, 6 Jan 2010, John Kacur wrote:

> On Wed, Jan 6, 2010 at 9:45 PM, Michal Marek <mmarek@xxxxxxx> wrote:
> > John Kacur napsal(a):
> >> Yes, I doubled checked that the problem exists, and it is quite easy for me to
> >> reproduce. However, my proposed solution is also broken, please don't
> >> apply, I'm still investigating.
> >>
> >> I am surprised that you are not able to reproduce the problem though.
> >> Did you follow the steps I that I outlined?
> >
> > I did
> >
> > $ git checkout v2.6.33-rc3
> > $ mkdir /bld/2.6.33-rc3
> > $ zcat /proc/config.gz >/bld/2.6.33-rc3/.config
> > $ make O=/bld/2.6.33-rc3/ oldconfig
> > ...
> > hit Enter several times
> > ...
> > $ ls -ld include/config /bld/2.6.33-rc3/include/config/
> > ls: cannot access include/config: No such file or directory
> > drwxr-xr-x 2 mmarek users 4096 2010-01-06 21:35
> > /bld/2.6.33-rc3/include/config//
> > $ make O=/bld/2.6.33-rc3/
> >  GEN     /bld/2.6.33-rc3/Makefile
> > scripts/kconfig/conf -s arch/x86/Kconfig
> >  Using /home/mmarek/linux-2.6 as source for kernel
> >  GEN     /bld/2.6.33-rc3/Makefile
> >  CHK     include/linux/version.h
> >  UPD     include/linux/version.h
> >  CHK     include/generated/utsrelease.h
> >  UPD     include/generated/utsrelease.h
> >  CC      kernel/bounds.s
> > ... continues building ...
> >
> >
> > The mkdir command has been in the Makefile since 2006 (c955cca), so I
> > think that your problem is caused by something else. Try a make V=1
> > build with a read-only source tree to see which mkdir command fails.
> >
> 
> Michal: The length of time that a bug exists in a piece of code is no
> argument for
> it's correctness!
> 
> I tried to debug this using
> make -d V=1 O=/bld/2.6.33-rc3
> and discovered that the bug did not always occur, but did sometimes.
> This leads me to think that it is timing sensitive, and indeed the
> problem shows up
> more easily on a machine with multiple processors.
> 
> Is it possible that the step with mkdir -p can sometimes occur in a
> Makefile parallel process
> before the cd KBUILD_OUTPUT occurs? That would explain why it doesn't
> reliably reproduce.
> 
> In any case, the idea behind my original patch is good, just specify
> the full path
> using the objtree variable and the problem goes away. The first round of my
> implementation was simply lacking.
> 
> Following up this note with a patch.
> 
> John
>