On Wed, 2019-09-11 at 14:04 +0100, Ben Hutchings wrote:
> On Wed, 2019-09-11 at 21:17 +0900, Masahiro Yamada wrote:
> > Hi Ben,
> >
> >
> > Thanks for this.
> > Please let me add some comments.
> >
> >
> > On Wed, Sep 11, 2019 at 8:54 PM Ben Hutchings <ben@xxxxxxxxxxxxxxx> wrote:
> [...]
> > > +Absolute filenames
> > > +------------------
> > > +
> > > +When the kernel is built out-of-tree, debug information may include
> > > +absolute filenames for the source files. The ``__FILE__`` macro may
> > > +also expand to an absolute filename. This must be overridden by
> > > +including `prefix-map options`_ in the `KCFLAGS`_ variable.
> >
> > Do you mean -fmacro-prefix-map ?
>
> No, I mean -ffile-prefix-map or the older -fdebug-prefix-map.
>
> > If so, it is already taken care of by the top Makefile.
> > If you use GCC 8 or newer, it is automatically added to
> > KBUILD_CFLAGS.
>
> Ah, that's helpful. So, I suppose I should just mention
> -fdebug-prefix-map here and warn that __FILE__ will still be a proble
> if using older compiler versions.
My revised text for this section is:
---
When the kernel is built out-of-tree, debug information may include
absolute filenames for the source files. This must be overridden by
including the ``-fdebug-prefix-map`` option in the `KCFLAGS`_ variable.
Depending on the compiler used, the ``__FILE__`` macro may also expand
to an absolute filename in an out-of-tree build. Kbuild automatically
uses the ``-fmacro-prefix-map`` option to prevent this, if it is
supported.
The Reproducible Builds web site has more information about these
`prefix-map options`_.
---
Does that look OK to you?
> > > +Generated files in source packages
> > > +----------------------------------
> > > +
> > > +The build processes for some programs under the ``tools/``
> > > +subdirectory do not completely support out-of-tree builds. This may
> > > +cause source packages built using e.g. ``make rpm-pkg`` to include
> > > +generated files and so be unreproducible. It may be necessary to
> > > +clean the source tree completely (``make mrproper`` or
> > > +``git clean -d -f -x``) before building a source package.
> >
> > Currently, the source package building does not support
> > out-of-tree build anyway.
>
> Yes, I realise that.
>
> > 'make O=foo rpm-pkg' fails with an error message.
> >
> > Building in a pristine source will solve the issue.
> [...]
>
> The issue I'm thinking about is that an out-of-tree build, prior to the
> package build, *should* leave the source pristine and sometimes does
> not.
>
> For Debian's official kernel packages, we build a binary package of the
> upstream source, and at some times this has unexpectedly included some
> generated files. I believe a similar issue would affect the upstream
> package scripts.
My revised text for this section is:
---
The build processes for some programs under the ``tools/``
subdirectory do not completely support out-of-tree builds. This may
cause a later source package build using e.g. ``make rpm-pkg`` to
include generated files. You should ensure the source tree is
pristine by running ``make mrproper`` or ``git clean -d -f -x`` before
building a source package.
---
Ben.
--
Ben Hutchings
The obvious mathematical breakthrough [to break modern encryption]
would be development of an easy way to factor large prime numbers.
- Bill Gates
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