[PATCH v1 0/1] scripts: Fix "make gtags" for O= kernel builds

[PATCH v1 0/1] scripts: Fix "make gtags" for O= kernel builds

[Ahmed S. Darwish]

Hi,

make gtags for O= kernel builds is currently broken. For example, when doing:

   make O=../build/ x86_64_defconfig
   make O=../build/ gtags

gtags generates a warning for each kernel source file to be indexed:

   make[1]: Entering directory '/home/darwi/build'
     GEN     gtags
   Warning: '/home/darwi/linux/arch/x86/include/asm/qspinlock.h' is out of source tree. ignored.
   Warning: '/home/darwi/linux/arch/x86/include/asm/hpet.h' is out of source tree. ignored.
   ...
   Warning: '/home/darwi/linux/virt/lib/irqbypass.c' is out of source tree. ignored.
   make[1]: Leaving directory '/home/darwi/build/'

and then generates an empty index:

   $ du -hs ~/build/G*
   16K	/home/darwi/build/GPATH
   16K	/home/darwi/build/GRTAGS
   16K	/home/darwi/build/GTAGS

This series includes a proposed fix. After applying it:

   $ make O=../build/ gtags
   make[1]: Entering directory '/home/darwi/build'
     GEN     gtags
   make[1]: Leaving directory '/home/darwi/build'

   $ du -hs ~/build/G*
   9.1M	/home/darwi/build/GPATH
   506M	/home/darwi/build/GRTAGS
   696M	/home/darwi/build/GTAGS

The generated files can then be integrated with editors or IDEs as
usual.

Thanks,

=>

Ahmed S. Darwish (1):
  scripts/tags.sh: Fix gtags generation for O= kernel builds

 scripts/tags.sh | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

base-commit: 1a5304fecee523060f26e2778d9d8e33c0562df3
--
2.30.2

[PATCH v1 1/1] scripts/tags.sh: Fix gtags generation for O= kernel builds

[Ahmed S. Darwish]

gtags considers any file outside of its current working directory
"outside the source tree" and refuses to index it.

For O= kernel builds, scripts/tags.sh invokes gtags with the current
working directory set to ${O}. This leads to gtags ignoring the entire
kernel source and generating an empty index.

For O= builds, set gtags' working directory to the kernel source tree
and explicitly set its output path through parameters instead.

Signed-off-by: Ahmed S. Darwish <darwi@linutronix.de>
---
 scripts/tags.sh | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/scripts/tags.sh b/scripts/tags.sh
index ea31640b2671..1a6db535503b 100755
--- a/scripts/tags.sh
+++ b/scripts/tags.sh
@@ -131,7 +131,14 @@ docscope()
 
 dogtags()
 {
-	all_target_sources | gtags -i -f -
+	# gtags refuses to index any file outside of the current working
+	# directory. For O= builds, set the current working directory to
+	# the kernel source tree and the output tags dir to ${O}.
+	suffixparams=
+	if [ -v O ]; then
+		suffixparams="-C $tree $O"
+	fi
+	all_target_sources | gtags -i -f - $suffixparams
 }
 
 # Basic regular expressions with an optional /kind-spec/ for ctags and
-- 
2.30.2

Re: [PATCH v1 1/1] scripts/tags.sh: Fix gtags generation for O= kernel builds

[Nathan Chancellor]

On Thu, May 04, 2023 at 10:18:33PM +0200, Ahmed S. Darwish wrote:
> gtags considers any file outside of its current working directory
> "outside the source tree" and refuses to index it.
> 
> For O= kernel builds, scripts/tags.sh invokes gtags with the current
> working directory set to ${O}. This leads to gtags ignoring the entire
> kernel source and generating an empty index.
> 
> For O= builds, set gtags' working directory to the kernel source tree
> and explicitly set its output path through parameters instead.
> 
> Signed-off-by: Ahmed S. Darwish <darwi@linutronix.de>

Reviewed-by: Nathan Chancellor <nathan@kernel.org>

> ---
>  scripts/tags.sh | 9 ++++++++-
>  1 file changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/scripts/tags.sh b/scripts/tags.sh
> index ea31640b2671..1a6db535503b 100755
> --- a/scripts/tags.sh
> +++ b/scripts/tags.sh
> @@ -131,7 +131,14 @@ docscope()
>  
>  dogtags()
>  {
> -	all_target_sources | gtags -i -f -
> +	# gtags refuses to index any file outside of the current working
> +	# directory. For O= builds, set the current working directory to
> +	# the kernel source tree and the output tags dir to ${O}.
> +	suffixparams=
> +	if [ -v O ]; then

I think

  if [ -n "$O" ]; then

would match the style preferred by Kbuild (though that is usually for
portability sake, which probably does not matter here since bash is
explicitly requested). Perhaps not worth addressing if there is no other
reason for a v2.

> +		suffixparams="-C $tree $O"
> +	fi
> +	all_target_sources | gtags -i -f - $suffixparams
>  }
>  
>  # Basic regular expressions with an optional /kind-spec/ for ctags and
> -- 
> 2.30.2
> 

Re: [PATCH v1 1/1] scripts/tags.sh: Fix gtags generation for O= kernel builds

[Ahmed S. Darwish]

Hi Nathan,

On Thu, 04 May 2023, Nathan Chancellor wrote:
>
> On Thu, May 04, 2023 at 10:18:33PM +0200, Ahmed S. Darwish wrote:
...
> > +	suffixparams=
> > +	if [ -v O ]; then
>
> I think
>
>   if [ -n "$O" ]; then
>
> would match the style preferred by Kbuild (though that is usually for
> portability sake, which probably does not matter here since bash is
> explicitly requested). Perhaps not worth addressing if there is no other
> reason for a v2.
>

Thanks, I'll do it. I've just discovered that a v2 is necessary anyway.

If O= has a "~", for example as in:

    make O=~/build/ gtags

the snippet below:

> > +		suffixparams="-C $tree $O"
> > +	fi
> > +	all_target_sources | gtags -i -f - $suffixparams
                                           ^
will fail since the "~" in the O= directory path won't get dereferenced
before getting passed to the gtags call (an eval is needed).

I'll submit a v2 shortly.

Kind regards,

--
Ahmed S. Darwish
Linutronix GmbH

Re: [PATCH v1 1/1] scripts/tags.sh: Fix gtags generation for O= kernel builds

[Masahiro Yamada]

On Fri, May 5, 2023 at 12:00 AM Ahmed S. Darwish <darwi@linutronix.de> wrote:
>
> Hi Nathan,
>
> On Thu, 04 May 2023, Nathan Chancellor wrote:
> >
> > On Thu, May 04, 2023 at 10:18:33PM +0200, Ahmed S. Darwish wrote:
> ...
> > > +   suffixparams=
> > > +   if [ -v O ]; then
> >
> > I think
> >
> >   if [ -n "$O" ]; then
> >
> > would match the style preferred by Kbuild (though that is usually for
> > portability sake, which probably does not matter here since bash is
> > explicitly requested). Perhaps not worth addressing if there is no other
> > reason for a v2.
> >
>
> Thanks, I'll do it. I've just discovered that a v2 is necessary anyway.
>
> If O= has a "~", for example as in:
>
>     make O=~/build/ gtags
>
> the snippet below:
>
> > > +           suffixparams="-C $tree $O"
> > > +   fi
> > > +   all_target_sources | gtags -i -f - $suffixparams
>                                            ^
> will fail since the "~" in the O= directory path won't get dereferenced
> before getting passed to the gtags call (an eval is needed).
>
> I'll submit a v2 shortly.
>
> Kind regards,
>
> --
> Ahmed S. Darwish
> Linutronix GmbH



It is wrong to check whether you are building out of the
source tree.  See line 159 of the Makefile.

BTW, this patch does not work for me.
It spits a ton of "not found" warnings, then generates
empty tags.


$ make O=build gtags
make[1]: Entering directory '/home/masahiro/ref/linux/build'
  GEN     gtags
Warning: '../arch/x86/include/asm/vmalloc.h' not found. ignored.
Warning: '../arch/x86/include/asm/pgtable-3level_types.h' not found. ignored.
Warning: '../arch/x86/include/asm/paravirt.h' not found. ignored.
Warning: '../arch/x86/include/asm/text-patching.h' not found. ignored.
Warning: '../arch/x86/include/asm/softirq_stack.h' not found. ignored.
Warning: '../arch/x86/include/asm/intel_ds.h' not found. ignored.
Warning: '../arch/x86/include/asm/resctrl.h' not found. ignored.
Warning: '../arch/x86/include/asm/setup_arch.h' not found. ignored.
Warning: '../arch/x86/include/asm/simd.h' not found. ignored.
Warning: '../arch/x86/include/asm/mmconfig.h' not found. ignored.
Warning: '../arch/x86/include/asm/pgtable_types.h' not found. ignored.
Warning: '../arch/x86/include/asm/mem_encrypt.h' not found. ignored.
Warning: '../arch/x86/include/asm/dmi.h' not found. ignored.
Warning: '../arch/x86/include/asm/thermal.h' not found. ignored.

    ...













-- 
Best Regards
Masahiro Yamada

Re: [PATCH v1 1/1] scripts/tags.sh: Fix gtags generation for O= kernel builds

[Masahiro Yamada]

On Fri, May 5, 2023 at 7:13 AM Masahiro Yamada <masahiroy@kernel.org> wrote:
>
> On Fri, May 5, 2023 at 12:00 AM Ahmed S. Darwish <darwi@linutronix.de> wrote:
> >
> > Hi Nathan,
> >
> > On Thu, 04 May 2023, Nathan Chancellor wrote:
> > >
> > > On Thu, May 04, 2023 at 10:18:33PM +0200, Ahmed S. Darwish wrote:
> > ...
> > > > +   suffixparams=
> > > > +   if [ -v O ]; then
> > >
> > > I think
> > >
> > >   if [ -n "$O" ]; then
> > >
> > > would match the style preferred by Kbuild (though that is usually for
> > > portability sake, which probably does not matter here since bash is
> > > explicitly requested). Perhaps not worth addressing if there is no other
> > > reason for a v2.
> > >
> >
> > Thanks, I'll do it. I've just discovered that a v2 is necessary anyway.
> >
> > If O= has a "~", for example as in:
> >
> >     make O=~/build/ gtags
> >
> > the snippet below:
> >
> > > > +           suffixparams="-C $tree $O"
> > > > +   fi
> > > > +   all_target_sources | gtags -i -f - $suffixparams
> >                                            ^
> > will fail since the "~" in the O= directory path won't get dereferenced
> > before getting passed to the gtags call (an eval is needed).
> >
> > I'll submit a v2 shortly.
> >
> > Kind regards,
> >
> > --
> > Ahmed S. Darwish
> > Linutronix GmbH
>
>
>
> It is wrong to check whether you are building out of the
> source tree.  See line 159 of the Makefile.

Let me correct this sentense.


It is wrong to use 'O' to check whether you are building out of the
source tree.





-- 
Best Regards
Masahiro Yamada

Re: [PATCH v1 1/1] scripts/tags.sh: Fix gtags generation for O= kernel builds

[Ahmed S. Darwish]

Hi Masahiro,

On Fri, 05 May 2023, Masahiro Yamada wrote:
>
> It is wrong to check whether you are building out of the
> source tree.  See line 159 of the Makefile.
>

Oh, didn't think about that case. Thanks for the reference and the
further clarification in reply.

I'll remove the ${O} check then and use saner mechanisms.

> BTW, this patch does not work for me.
> It spits a ton of "not found" warnings, then generates
> empty tags.
>
>
> $ make O=build gtags

Interesting...

When doing:

  $ make O=../build gtags

  scripts/tags.sh "$tree" variable is set to the absolute path of the
  kernel source tree. Thus all the paths fed to gtags are absolute and
  this patch series works.

When doing what you tested with:

  $ make O=build/ gtags

  scripts/tags.sh "$tree" variable is set to the path of the kernel
  source tree *relative* to O=build/. So in that case kernel source
  "$tree" equals ".."

  With this series, the build will fail as gtags current working dir is
  the kernel source tree, and all the fed paths are thus invalid as
  they're relative to O=build/ instead.

  Without this series the build will still fail given the original
  problem of having the files "outside the source tree", where gtags
  thinks the source tree is "build/".

I'll think of something that can cover the both cases.

Kind regards,
Ahmed

--
Linutronix GmbH

[PATCH v2 0/2] scripts: Resolve gtags empty index generation

[Ahmed S. Darwish]

Hi,

v2-changelog
------------

Handle review remarks from Masahiro Yamada:

  - scripts/tags.sh: remove the O= language, and focus on the general
    case of the build directory being different from the kernel source
    tree, as specified in kernel Makefile L159.

  - Fix failure when build directory is a subdirectory of the kernel
    source tree.

NEW:

  - Update Documentation/process/changes.rst with new gtags (GNU GLOBAL)
    requirements.

Thanks!

Cover letter / v1
-----------------

https://lkml.kernel.org/r/20230504201833.202494-1-darwi@linutronix.de

make gtags for O= kernel builds is currently broken. For example, when doing:

   make O=../build/ x86_64_defconfig
   make O=../build/ gtags

gtags generates a warning for each kernel source file to be indexed:

   make[1]: Entering directory '/home/darwi/build'
     GEN     gtags
   Warning: '/home/darwi/linux/arch/x86/include/asm/qspinlock.h' is out of source tree. ignored.
   Warning: '/home/darwi/linux/arch/x86/include/asm/hpet.h' is out of source tree. ignored.
   ...
   Warning: '/home/darwi/linux/virt/lib/irqbypass.c' is out of source tree. ignored.
   make[1]: Leaving directory '/home/darwi/build/'

and then generates an empty index:

   $ du -hs ~/build/G*
   16K	/home/darwi/build/GPATH
   16K	/home/darwi/build/GRTAGS
   16K	/home/darwi/build/GTAGS

This series includes a proposed fix. After applying it:

   $ make O=../build/ gtags
   make[1]: Entering directory '/home/darwi/build'
     GEN     gtags
   make[1]: Leaving directory '/home/darwi/build'

   $ du -hs ~/build/G*
   9.1M	/home/darwi/build/GPATH
   506M	/home/darwi/build/GRTAGS
   696M	/home/darwi/build/GTAGS

The generated files can then be integrated with editors or IDEs as
usual.

=>

Ahmed S. Darwish (2):
  scripts/tags.sh: Resolve gtags empty index generation
  docs: Set minimal gtags / GNU GLOBAL version to 6.6.5

 Documentation/process/changes.rst |  7 +++++++
 scripts/tags.sh                   | 14 +++++++++++++-
 2 files changed, 20 insertions(+), 1 deletion(-)

base-commit: ba0ad6ed89fd5dada3b7b65ef2b08e95d449d4ab
--
2.40.0

[PATCH v2 1/2] scripts/tags.sh: Resolve gtags empty index generation

[Ahmed S. Darwish]

gtags considers any file outside of its current working directory
"outside the source tree" and refuses to index it. For O= kernel builds,
or when "make" is invoked from a directory other then the kernel source
tree, gtags ignores the entire kernel source and generates an empty
index.

Force-set gtags current working directory to the kernel source tree.

Due to commit 9da0763bdd82 ("kbuild: Use relative path when building in
a subdir of the source tree"), if the kernel build is done in a
sub-directory of the kernel source tree, the kernel Makefile will set
the kernel's $srctree to ".." for shorter compile-time and run-time
warnings. Consequently, the list of files to be indexed will be in the
"../*" form, rendering all such paths invalid once gtags switches to the
kernel source tree as its current working directory.

If gtags indexing is requested and the build directory is not the kernel
source tree, index all files in absolute-path form.

Note, indexing in absolute-path form will not affect the generated
index, as paths in gtags indices are always relative to the gtags "root
directory" (as evidenced by "gtags --dump").

Signed-off-by: Ahmed S. Darwish <darwi@linutronix.de>
Cc: <stable@vger.kernel.org>
---
 scripts/tags.sh | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/scripts/tags.sh b/scripts/tags.sh
index ea31640b2671..3de4b4ebd891 100755
--- a/scripts/tags.sh
+++ b/scripts/tags.sh
@@ -32,6 +32,14 @@ else
 	tree=${srctree}/
 fi
 
+
+# gtags(1) refuses to index any file outside of its current working dir.
+# If gtags indexing is requested and the build output directory is not
+# the kernel source tree, index all files in absolute-path form.
+if [ "$1" = "gtags" -a -n "${tree}" ]; then
+	tree=$(realpath $tree)/
+fi
+
 # Detect if ALLSOURCE_ARCHS is set. If not, we assume SRCARCH
 if [ "${ALLSOURCE_ARCHS}" = "" ]; then
 	ALLSOURCE_ARCHS=${SRCARCH}
@@ -131,7 +139,11 @@ docscope()
 
 dogtags()
 {
-	all_target_sources | gtags -i -f -
+	local gtagsoutdir="${PWD}"
+	local gtagsroot="${tree}"
+
+	[ -z "${gtagsroot}" ] && gtagsroot="."
+	all_target_sources | gtags -i -C $gtagsroot -f - $gtagsoutdir
 }
 
 # Basic regular expressions with an optional /kind-spec/ for ctags and
-- 
2.40.0

[PATCH v2 2/2] docs: Set minimal gtags / GNU GLOBAL version to 6.6.5

[Ahmed S. Darwish]

Kernel build now uses the gtags "-C (--directory)" option, available
since GNU GLOBAL v6.6.5.  Update the documentation accordingly.

Signed-off-by: Ahmed S. Darwish <darwi@linutronix.de>
Cc: <stable@vger.kernel.org>
Link: https://lists.gnu.org/archive/html/info-global/2020-09/msg00000.html
---
 Documentation/process/changes.rst | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/Documentation/process/changes.rst b/Documentation/process/changes.rst
index ef540865ad22..a9ef00509c9b 100644
--- a/Documentation/process/changes.rst
+++ b/Documentation/process/changes.rst
@@ -60,6 +60,7 @@ openssl & libcrypto    1.0.0            openssl version
 bc                     1.06.95          bc --version
 Sphinx\ [#f1]_         1.7              sphinx-build --version
 cpio                   any              cpio --version
+gtags (optional)       6.6.5            gtags --version
 ====================== ===============  ========================================
 
 .. [#f1] Sphinx is needed only to build the Kernel documentation
@@ -174,6 +175,12 @@ You will need openssl to build kernels 3.7 and higher if module signing is
 enabled.  You will also need openssl development packages to build kernels 4.3
 and higher.
 
+gtags / GNU GLOBAL (optional)
+-----------------------------
+
+The kernel build requires GNU GLOBAL version 6.6.5 or later to generate
+tag files through ``make gtags``.  This is due to its use of the gtags
+``-C (--directory)`` flag.
 
 System utilities
 ****************
-- 
2.40.0

Re: [PATCH v2 1/2] scripts/tags.sh: Resolve gtags empty index generation

[Masahiro Yamada]

On Tue, May 9, 2023 at 10:26 AM Ahmed S. Darwish <darwi@linutronix.de> wrote:
>
> gtags considers any file outside of its current working directory
> "outside the source tree" and refuses to index it. For O= kernel builds,
> or when "make" is invoked from a directory other then the kernel source
> tree, gtags ignores the entire kernel source and generates an empty
> index.
>
> Force-set gtags current working directory to the kernel source tree.
>
> Due to commit 9da0763bdd82 ("kbuild: Use relative path when building in
> a subdir of the source tree"), if the kernel build is done in a
> sub-directory of the kernel source tree, the kernel Makefile will set
> the kernel's $srctree to ".." for shorter compile-time and run-time
> warnings. Consequently, the list of files to be indexed will be in the
> "../*" form, rendering all such paths invalid once gtags switches to the
> kernel source tree as its current working directory.
>
> If gtags indexing is requested and the build directory is not the kernel
> source tree, index all files in absolute-path form.
>
> Note, indexing in absolute-path form will not affect the generated
> index, as paths in gtags indices are always relative to the gtags "root
> directory" (as evidenced by "gtags --dump").

The code works as claimed, but I am just curious.
If all the paths are relative, how can you use the tags files located
in a separate directory?

"make O=foo gtags" creates tags files in foo/.
I want to use them from emacs.
emacs cannot find the right file because
it assumes the path is relative to 'foo' instead of the source tree.

I set GTAGSROOT to the source tree, but I could not find a way
to use it in a useful way.



> diff --git a/scripts/tags.sh b/scripts/tags.sh
> index ea31640b2671..3de4b4ebd891 100755
> --- a/scripts/tags.sh
> +++ b/scripts/tags.sh
> @@ -32,6 +32,14 @@ else
>         tree=${srctree}/
>  fi
>
> +

Unneeded empty line addition.


> +# gtags(1) refuses to index any file outside of its current working dir.
> +# If gtags indexing is requested and the build output directory is not
> +# the kernel source tree, index all files in absolute-path form.
> +if [ "$1" = "gtags" -a -n "${tree}" ]; then
> +       tree=$(realpath $tree)/


I decided to run shellcheck for new code.
Please follow the suggestion from the tool.


In scripts/tags.sh line 40:
tree=$(realpath $tree)/
                        ^---^ SC2086 (info): Double quote to prevent
globbing and word splitting.

Did you mean:
tree=$(realpath "$tree")/



(You do not need to fix the entire script.
This is only for new code).



> @@ -131,7 +139,11 @@ docscope()
>
>  dogtags()
>  {
> -       all_target_sources | gtags -i -f -
> +       local gtagsoutdir="${PWD}"
> +       local gtagsroot="${tree}"
> +
> +       [ -z "${gtagsroot}" ] && gtagsroot="."
> +       all_target_sources | gtags -i -C $gtagsroot -f - $gtagsoutdir
>  }


You can write it in one line.


dogtags()
{
    all_target_sources | gtags -i -C "${tree:-.}" -f - "${PWD}"
}





--
Best Regards
Masahiro Yamada

Re: [PATCH v2 1/2] scripts/tags.sh: Resolve gtags empty index generation

[Ahmed S. Darwish]

On Fri, 12 May 2023, Masahiro Yamada wrote:
>
> The code works as claimed, but I am just curious.

Thanks.

> If all the paths are relative, how can you use the tags files located
> in a separate directory?
>
> "make O=foo gtags" creates tags files in foo/.
> I want to use them from emacs.
> emacs cannot find the right file because
> it assumes the path is relative to 'foo' instead of the source tree.
>

Correct.

In theory, since all the indexed linux source tree paths at the gtags
generated files (GPATH/GRTAGS/GTAGS) are relative to the linux source
tree root, opening such files from emacs ggtags-mode, *wherever* these
files are, "should" work.

In practice, ggtags/global (and thus also emacs ggtags-mode) operate
with a model of the world where all indexed files must be under the
source "root directory". So, the GPATH/GRTAGS/GTAGS files are expected
to be under the source tree (except in special GTAGSLIBPATH= cases).

> I set GTAGSROOT to the source tree, but I could not find a way
> to use it in a useful way.

Yes, that won't work, as emacs will search for the G* database files
under that folder instead.

Meanwhile setting GTAGSROOT to the O= directory, or to a build directory
that is different from the kernel source tree, as in:

  cd ~/linux
  O=~/build/build-linux-x86
  make O=$O x86_64_defconfig
  make O=$O gtags
  GTAGSROOT=$O emacs init/main.c

will "mostly" succeed (as you hinted at):

  M-x ggtags-mode

  # emacs finds gtags files under ${GTAGSROOT} and sets ${GTAGSROOT} as
  # the root of the project

  M-x ggtags-find-definition
  Definition: rcu_read_lock

    -*- mode: ggtags-global; default-directory: "~/build/build-linux-x86/" -*-
    Global started at Mon May 15 15:54:01

    global -v --result=grep --color=always --path-style=shorter -- rcu_read_lock
    include/linux/rcupdate.h:769:static __always_inline void rcu_read_lock(void)
    1 object located (using '/home/darwi/build/build-linux-x86/GTAGS').

    Global found 1 definition at Mon May 15 15:54:01

  # Prompt
  Find this match in (default include/linux/rcupdate.h)?: ~/build/build-linux-x86/
  ^^^

But at the Prompt step above, things break.

In a fully working setup, this prompt will not be shown and emacs just
jumps to rcuupdate.h line 769.

What I personally do to mitigate that problem is:

    cd ~/linux
    for f in GTAGS GRTAGS GPATH; do
        ln -vsf ${O}/$f .
    done

and switch these symlinks through minor local shell plumbing whenever
I'm switching kernel projects with different build directories.

It is not ideal, but maybe we can discuss this with the global(1) people
at a later step. At least with this patch series, "make O=xyz/ gtags"
produces a valid index.

>
> > +# gtags(1) refuses to index any file outside of its current working dir.
> > +# If gtags indexing is requested and the build output directory is not
> > +# the kernel source tree, index all files in absolute-path form.
> > +if [ "$1" = "gtags" -a -n "${tree}" ]; then
> > +       tree=$(realpath $tree)/
>
> I decided to run shellcheck for new code.
> Please follow the suggestion from the tool.
>
> In scripts/tags.sh line 40:
> tree=$(realpath $tree)/
>                         ^---^ SC2086 (info): Double quote to prevent
> globbing and word splitting.
>
> Did you mean:
> tree=$(realpath "$tree")/
>
> (You do not need to fix the entire script.
> This is only for new code).
>

Yes, the reason was to following the existing coding pattern at
scripts/tags.sh.  But, sure, will do.

>
> > @@ -131,7 +139,11 @@ docscope()
> >
> >  dogtags()
> >  {
> > -       all_target_sources | gtags -i -f -
> > +       local gtagsoutdir="${PWD}"
> > +       local gtagsroot="${tree}"
> > +
> > +       [ -z "${gtagsroot}" ] && gtagsroot="."
> > +       all_target_sources | gtags -i -C $gtagsroot -f - $gtagsoutdir
> >  }
>
> You can write it in one line.
>
> dogtags()
> {
>     all_target_sources | gtags -i -C "${tree:-.}" -f - "${PWD}"
> }
>

Ditto. The script was almost-fully POSIX style (except the first line),
so I avoided bash features on purpose.

I personlly always prefer using Bash features though, so I'll definitely
update the code.

Thanks a lot for the review. I'll send a v3.

--
Ahmed S. Darwish
Linutronix GmbH

Re: [PATCH v2 1/2] scripts/tags.sh: Resolve gtags empty index generation

[Ahmed S. Darwish]

On Mon, 15 May 2023, Ahmed S. Darwish wrote:
> On Fri, 12 May 2023, Masahiro Yamada wrote:
> >
> > You can write it in one line.
> >
> > dogtags()
> > {
> >     all_target_sources | gtags -i -C "${tree:-.}" -f - "${PWD}"
> > }
> >
>
> Ditto. The script was almost-fully POSIX style (except the first line),
> so I avoided bash features on purpose.
>

Nitpick for correctness sake the "Use default values" parameter
expansion is actually POSIX-ly correct:

  https://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_06_02

Thanks,
Ahmed

[PATCH v3 0/2] scripts: Resolve gtags empty index generation

[Ahmed S. Darwish]

Hi,

v3-changelog
------------

Handle review remarks from Masahiro Yamada:

  - Apply shellcheck on new "scripts/tags.sh" code.

  - Shorten code through shell's "default value" parameter expansion.

NEW:

  - Cc docs maintainer (Documentation/process/changes.rst change).

Thanks!

v2-changelog
------------

https://lkml.kernel.org/r/20230509012616.81579-1-darwi@linutronix.de

Handle review remarks from Masahiro Yamada:

  - scripts/tags.sh: remove the O= language, and focus on the general
    case of the build directory being different from the kernel source
    tree, as specified in kernel Makefile L159.

  - Fix failure when build directory is a subdirectory of the kernel
    source tree.

NEW:

  - Update Documentation/process/changes.rst with new gtags (GNU GLOBAL)
    requirements.

Thanks!

Cover letter / v1
-----------------

https://lkml.kernel.org/r/20230504201833.202494-1-darwi@linutronix.de

make gtags for O= kernel builds is currently broken. For example, when doing:

   make O=../build/ x86_64_defconfig
   make O=../build/ gtags

gtags generates a warning for each kernel source file to be indexed:

   make[1]: Entering directory '/home/darwi/build'
     GEN     gtags
   Warning: '/home/darwi/linux/arch/x86/include/asm/qspinlock.h' is out of source tree. ignored.
   Warning: '/home/darwi/linux/arch/x86/include/asm/hpet.h' is out of source tree. ignored.
   ...
   Warning: '/home/darwi/linux/virt/lib/irqbypass.c' is out of source tree. ignored.
   make[1]: Leaving directory '/home/darwi/build/'

and then generates an empty index:

   $ du -hs ~/build/G*
   16K	/home/darwi/build/GPATH
   16K	/home/darwi/build/GRTAGS
   16K	/home/darwi/build/GTAGS

This series includes a proposed fix. After applying it:

   $ make O=../build/ gtags
   make[1]: Entering directory '/home/darwi/build'
     GEN     gtags
   make[1]: Leaving directory '/home/darwi/build'

   $ du -hs ~/build/G*
   9.1M	/home/darwi/build/GPATH
   506M	/home/darwi/build/GRTAGS
   696M	/home/darwi/build/GTAGS

The generated files can then be integrated with editors or IDEs as
usual.

=>

Ahmed S. Darwish (2):
  scripts/tags.sh: Resolve gtags empty index generation
  docs: Set minimal gtags / GNU GLOBAL version to 6.6.5

 Documentation/process/changes.rst | 7 +++++++
 scripts/tags.sh                   | 9 ++++++++-
 2 files changed, 15 insertions(+), 1 deletion(-)

base-commit: f1fcbaa18b28dec10281551dfe6ed3a3ed80e3d6
--
2.30.2

[PATCH v3 1/2] scripts/tags.sh: Resolve gtags empty index generation

[Ahmed S. Darwish]

gtags considers any file outside of its current working directory
"outside the source tree" and refuses to index it. For O= kernel builds,
or when "make" is invoked from a directory other then the kernel source
tree, gtags ignores the entire kernel source and generates an empty
index.

Force-set gtags current working directory to the kernel source tree.

Due to commit 9da0763bdd82 ("kbuild: Use relative path when building in
a subdir of the source tree"), if the kernel build is done in a
sub-directory of the kernel source tree, the kernel Makefile will set
the kernel's $srctree to ".." for shorter compile-time and run-time
warnings. Consequently, the list of files to be indexed will be in the
"../*" form, rendering all such paths invalid once gtags switches to the
kernel source tree as its current working directory.

If gtags indexing is requested and the build directory is not the kernel
source tree, index all files in absolute-path form.

Note, indexing in absolute-path form will not affect the generated
index, as paths in gtags indices are always relative to the gtags "root
directory" anyway (as evidenced by "gtags --dump").

Signed-off-by: Ahmed S. Darwish <darwi@linutronix.de>
Cc: <stable@vger.kernel.org>
---
 scripts/tags.sh | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/scripts/tags.sh b/scripts/tags.sh
index ea31640b2671..f6b3c7cd39c7 100755
--- a/scripts/tags.sh
+++ b/scripts/tags.sh
@@ -32,6 +32,13 @@ else
 	tree=${srctree}/
 fi
 
+# gtags(1) refuses to index any file outside of its current working dir.
+# If gtags indexing is requested and the build output directory is not
+# the kernel source tree, index all files in absolute-path form.
+if [[ "$1" == "gtags" && -n "${tree}" ]]; then
+	tree=$(realpath "$tree")/
+fi
+
 # Detect if ALLSOURCE_ARCHS is set. If not, we assume SRCARCH
 if [ "${ALLSOURCE_ARCHS}" = "" ]; then
 	ALLSOURCE_ARCHS=${SRCARCH}
@@ -131,7 +138,7 @@ docscope()
 
 dogtags()
 {
-	all_target_sources | gtags -i -f -
+	all_target_sources | gtags -i -C "${tree:-.}" -f - "$PWD"
 }
 
 # Basic regular expressions with an optional /kind-spec/ for ctags and
-- 
2.30.2

[PATCH v3 2/2] docs: Set minimal gtags / GNU GLOBAL version to 6.6.5

[Ahmed S. Darwish]

Kernel build now uses the gtags "-C (--directory)" option, available
since GNU GLOBAL v6.6.5.  Update the documentation accordingly.

Signed-off-by: Ahmed S. Darwish <darwi@linutronix.de>
Cc: <stable@vger.kernel.org>
Link: https://lists.gnu.org/archive/html/info-global/2020-09/msg00000.html
---
 Documentation/process/changes.rst | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/Documentation/process/changes.rst b/Documentation/process/changes.rst
index ef540865ad22..a9ef00509c9b 100644
--- a/Documentation/process/changes.rst
+++ b/Documentation/process/changes.rst
@@ -60,6 +60,7 @@ openssl & libcrypto    1.0.0            openssl version
 bc                     1.06.95          bc --version
 Sphinx\ [#f1]_         1.7              sphinx-build --version
 cpio                   any              cpio --version
+gtags (optional)       6.6.5            gtags --version
 ====================== ===============  ========================================
 
 .. [#f1] Sphinx is needed only to build the Kernel documentation
@@ -174,6 +175,12 @@ You will need openssl to build kernels 3.7 and higher if module signing is
 enabled.  You will also need openssl development packages to build kernels 4.3
 and higher.
 
+gtags / GNU GLOBAL (optional)
+-----------------------------
+
+The kernel build requires GNU GLOBAL version 6.6.5 or later to generate
+tag files through ``make gtags``.  This is due to its use of the gtags
+``-C (--directory)`` flag.
 
 System utilities
 ****************
-- 
2.30.2

Re: [PATCH v3 0/2] scripts: Resolve gtags empty index generation

[Masahiro Yamada]

On Tue, May 16, 2023 at 2:33 AM Ahmed S. Darwish <darwi@linutronix.de> wrote:
>
> Hi,
>
> v3-changelog
> ------------
>
> Handle review remarks from Masahiro Yamada:
>
>   - Apply shellcheck on new "scripts/tags.sh" code.
>
>   - Shorten code through shell's "default value" parameter expansion.
>
> NEW:
>
>   - Cc docs maintainer (Documentation/process/changes.rst change).
>
> Thanks!
>
> v2-changelog
> ------------
>
> https://lkml.kernel.org/r/20230509012616.81579-1-darwi@linutronix.de
>
> Handle review remarks from Masahiro Yamada:
>
>   - scripts/tags.sh: remove the O= language, and focus on the general
>     case of the build directory being different from the kernel source
>     tree, as specified in kernel Makefile L159.
>
>   - Fix failure when build directory is a subdirectory of the kernel
>     source tree.
>
> NEW:
>
>   - Update Documentation/process/changes.rst with new gtags (GNU GLOBAL)
>     requirements.
>
> Thanks!
>
> Cover letter / v1
> -----------------
>
> https://lkml.kernel.org/r/20230504201833.202494-1-darwi@linutronix.de
>
> make gtags for O= kernel builds is currently broken. For example, when doing:
>
>    make O=../build/ x86_64_defconfig
>    make O=../build/ gtags
>
> gtags generates a warning for each kernel source file to be indexed:
>
>    make[1]: Entering directory '/home/darwi/build'
>      GEN     gtags
>    Warning: '/home/darwi/linux/arch/x86/include/asm/qspinlock.h' is out of source tree. ignored.
>    Warning: '/home/darwi/linux/arch/x86/include/asm/hpet.h' is out of source tree. ignored.
>    ...
>    Warning: '/home/darwi/linux/virt/lib/irqbypass.c' is out of source tree. ignored.
>    make[1]: Leaving directory '/home/darwi/build/'
>
> and then generates an empty index:
>
>    $ du -hs ~/build/G*
>    16K  /home/darwi/build/GPATH
>    16K  /home/darwi/build/GRTAGS
>    16K  /home/darwi/build/GTAGS
>
> This series includes a proposed fix. After applying it:
>
>    $ make O=../build/ gtags
>    make[1]: Entering directory '/home/darwi/build'
>      GEN     gtags
>    make[1]: Leaving directory '/home/darwi/build'
>
>    $ du -hs ~/build/G*
>    9.1M /home/darwi/build/GPATH
>    506M /home/darwi/build/GRTAGS
>    696M /home/darwi/build/GTAGS
>
> The generated files can then be integrated with editors or IDEs as
> usual.
>
> =>
>
> Ahmed S. Darwish (2):
>   scripts/tags.sh: Resolve gtags empty index generation
>   docs: Set minimal gtags / GNU GLOBAL version to 6.6.5


Both applied. Thanks.




>
>  Documentation/process/changes.rst | 7 +++++++
>  scripts/tags.sh                   | 9 ++++++++-
>  2 files changed, 15 insertions(+), 1 deletion(-)
>
> base-commit: f1fcbaa18b28dec10281551dfe6ed3a3ed80e3d6
> --
> 2.30.2



-- 
Best Regards
Masahiro Yamada