Re: [Qemu-devel] [PATCH] Makefile: Avoid explicit list of directories in clean target

[Stefan Weil]

Am 31.07.2012 17:51, schrieb Peter Maydell:
> On 31 July 2012 16:49, Stefan Weil <address@hidden> wrote:
> > Yes, QEMU creates files in 3 levels. We could use
> >
> >      rm -f *.[od] */*.[od] */*/*.[od]
> >
> > I suggest using the wrapper $(call quiet-command,...)
> > to suppress printing of all removed file names.
>
> My worry was not so much what we print as that we
> might be exceeding the total command line length
> limits on some systems (whether you did it this way
> or via "rm -f $(find ...)").
>
> -- PMM

That's quite possible:

$ find -name "*.[od]"|wc
   4862    4862  151329
$ ls *.[od] */*.[od] */*/*.[od] */*/*/*.[od] */*/*/*/*.[od]|wc
   4862    4862  141605

(I was somewhat surprised to see that we use 5 levels of directories).

The command line would be more than 140000 characters which is indeed 
very long.

Separating .o and .d files and the levels reduces that number:

$ ls *.o|wc
     80      80     952
$ ls */*.o|wc
    819     819   20048
$ ls */*/*.o|wc
   1406    1406   45573
$ ls */*/*/*.o|wc
     87      87    2579
$ ls */*/*/*/*.o|wc
     16      16     796

The 2nd and the 3rd level are potentially critical, but they could be
split up further if needed.

What about removing support for in-tree builds?
For out-of-tree builds 'make distclean' is nearly trivial.

-- Stefan W.