Re: [Qemu-devel] [RFC PATCH qemu] git-submodule.sh: Do not try writing to source directory if not necessary

[Daniel P. Berrange]

On Thu, Oct 26, 2017 at 11:54:59AM +1100, Alexey Kardashevskiy wrote:
> On 26/10/17 08:11, Daniel P. Berrange wrote:
> > On Wed, Oct 25, 2017 at 07:10:40PM +1100, Alexey Kardashevskiy wrote:
> >> On 25/10/17 17:57, Daniel P. Berrange wrote:
> >>> On Wed, Oct 25, 2017 at 12:45:10PM +1100, Alexey Kardashevskiy wrote:
> >>>> On 25/10/17 03:27, Daniel P. Berrange wrote:
> >>>>> On Tue, Oct 24, 2017 at 07:58:53PM +1100, Alexey Kardashevskiy wrote:
> >>>>>> The new git-submodule.sh script writes .git-submodule-status to
> >>>>>> the source directory every time no matter what. This makes it 
> >>>>>> conditional.
> >>>>>>
> >>>>>> Signed-off-by: Alexey Kardashevskiy <address@hidden>
> >>>>>> ---
> >>>>>>
> >>>>>> I compile out of tree on a remote guest system where I mount the
> >>>>>> source directory as "readonly" and build directory as "rw" and
> >>>>>> scripts/git-submodule.sh tries writing to the source directory even 
> >>>>>> when
> >>>>>> I manually update modules on a host machine which is quite annoying.
> >>>>>>
> >>>>>> Is this something acceptable? Or I am missing something here?
> >>>>>
> >>>>> How did you update the modules - did you manually run  'git submodule 
> >>>>> update...'
> >>>>> or did you use the git-submodule.sh script on your host machine ?
> >>>>
> >>>>
> >>>> I run scripts/git-submodule.sh. Which is not thrilling either as I rather
> >>>> expect source tree not to be affected in any way when running "make".
> >>>
> >>> Oh, did you pass the list of sub-modules to it when running
> >>>
> >>> eg, ./scripts/git-submodule.sh update ui/keycodemapdb
> >>>
> >>> the list of submodules you need is printed in the configure output 
> >>> summary.
> >>
> >> Sure, otherwise it does nothing.
> >>
> >>
> >>>
> >>>>> If you run git-submodule.sh on the host, then it should save the status
> >>>>> file, and then when you run make on the guest system, it should notice
> >>>>> that you're already updated and never even invoke 'git-submodule.sh 
> >>>>> update'
> >>>>
> >>>>
> >>>> scripts/git-submodule.sh also tries writing to the source directory (I
> >>>> should probably have fixed that branch too) but this failure is not fatal
> >>>> for "make" but makes it want to try "update" and then "make" fails.
> >>>
> >>> This shouldn't have happened in your case though, if you have already run
> >>> 'git-submodule.sh update ...list of modules...' on the host machine, with
> >>> the same list of modules that the guest 'configure' printed out.
> >>
> >> It does not matter if I run git-submodule.sh or not - "git-submodule.sh
> >> status" will try writing to the read only folder anyway and it will fail
> >> and Makefile's  git_module_status will be set to 1.
> > 
> > 
> > Ahhhh, great, now I understand why you're hitting the problem !
> > 
> >> If I do as below (and that's what I should have done as I said), then
> >> "git-submodule.sh update" is not invoked and we are good. I am not
> >> reposting it yet as 1) my shell skills are crap (need to delete the temp
> >> file or rewrite the whole thing not to use temp file or rewrite it in
> >> python - why do not people use python everywhere?!) 2) I still hope we stop
> >> doing this from Makefile :)
> > 
> > I agree using a tmpfile is the right fix here.
> 
> 
> I still think not doing "git update" from Makefile is the right fix here,
> is that a final decision? Why cannot "configure" do this (and ideally have
> a way not to do this at all, like --no-git-submodules-update)?  Just
> checking...

That ends up doing exactly the same thing. We would need to make sure that
configure gets re-run when the submodules change. So you just go from having
'make' run git-submodule.sh, to have make run config.status which runs
configure, which runs git-submodule.sh. 

Regards,
Daniel
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