linux-kernel - Re: [PATCH v2] scripts/gdb: Ensure the absolute path is generated on initial source

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Date:   Wed, 14 Dec 2022 11:39:40 -0800
From:   Nick Desaulniers <ndesaulniers@...gle.com>
To:     Aaron Tomlin <atomlin@...hat.com>
Cc:     jan.kiszka@...mens.com, kbingham@...nel.org, atomlin@...mlin.com,
        linux-kernel@...r.kernel.org, dianders@...omium.org,
        Nathan Chancellor <nathan@...nel.org>
Subject: Re: [PATCH v2] scripts/gdb: Ensure the absolute path is generated on
 initial source

On Wed, Dec 14, 2022 at 10:57 AM Nick Desaulniers
<ndesaulniers@...gle.com> wrote:
>
> On Tue, Jul 12, 2022 at 12:02:48PM +0100, Aaron Tomlin wrote:
> > Post 'make scripts_gdb' a symbolic link to scripts/gdb/vmlinux-gdb.py
> > is created. Currently 'os.path.dirname(__file__)' does not generate
> > the absolute path to scripts/gdb resulting in the following:
> >
> >     (gdb) source vmlinux-gdb.py
> >     Traceback (most recent call last):
> >       File "scripts/gdb/vmlinux-gdb.py", line 25, in <module>
> >       import linux.utils
> >     ModuleNotFoundError: No module named 'linux'
>
> So I recently moved to a new machine, and lost my previous .gdbinit.
>
> I've re-added:
> add-auto-load-safe-path /path/to/linux/
>
> to my new ~/.gdbinit.
>
> Upon startup, lx-dmesg and friends aren't available.
>
> If I try:
> (gdb) source scripts/gdb/vmlinux-gdb.py
> Traceback (most recent call last):
>   File "scripts/gdb/vmlinux-gdb.py", line 25, in <module>
>     import linux.utils
> ModuleNotFoundError: No module named 'linux'
>
> Which is exactly the error claimed to be fixed by
> commit b99695580bfc ("scripts/gdb: ensure the absolute path is generated on initial source")
> even though I have b99695580bfc, which is how I found this thread to
> reply to.
>
> (gdb) show auto-load safe-path
> List of directories from which it is safe to auto-load files is $debugdir:$datadir/auto-load:/path/to/linux/.
>
> $ gdb-multiarch --version | head -n1
> GNU gdb (Debian 12.1-3) 12.1
> $ python3 --version
> Python 3.10.8
>
> I've also RTFM @
> Documentation/dev-tools/gdb-kernel-debugging.rst
> though perhaps there's something I've missed?
>
> $ grep -rn GDB_SCRIPTS .config
> 4162:CONFIG_GDB_SCRIPTS=y
>
> This definitely has worked in the past for me, on my previous
> workstation.
>
> (gdb) show configuration
> ...
>              --with-python=/usr (relocatable)
>              --with-python-libdir=/usr/lib (relocatable)
> ...
> (gdb) apropos lx
> (gdb)
>
> No warnings from GDB either about the autoload path not being set.
> Running gdb in my top level kernel sources.
>
> Am I holding it wrong?
>
> Any tips on how to go about debugging this?

PEBKAC; looks like I was building `vmlinux` and not `all`. D'oh!

>
> >
> > This patch ensures that the absolute path to scripts/gdb in relation to
> > the given file is generated so each module can be located accordingly.
> >
> > Signed-off-by: Aaron Tomlin <atomlin@...hat.com>
> > ---
> >  scripts/gdb/vmlinux-gdb.py | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/scripts/gdb/vmlinux-gdb.py b/scripts/gdb/vmlinux-gdb.py
> > index 4136dc2c59df..3e8d3669f0ce 100644
> > --- a/scripts/gdb/vmlinux-gdb.py
> > +++ b/scripts/gdb/vmlinux-gdb.py
> > @@ -13,7 +13,7 @@
> >
> >  import os
> >
> > -sys.path.insert(0, os.path.dirname(__file__) + "/scripts/gdb")
> > +sys.path.insert(0, os.path.dirname(os.path.abspath(__file__)) + "/scripts/gdb")
> >
> >  try:
> >      gdb.parse_and_eval("0")
> > --
> > 2.34.3
> >
> >



-- 
Thanks,
~Nick Desaulniers