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Date:   Tue, 1 Jun 2021 12:13:21 -0700
From:   Kees Cook <keescook@chromium.org>
To:     Bill Wendling <morbo@google.com>
Cc:     Nathan Chancellor <nathan@kernel.org>,
        Jonathan Corbet <corbet@lwn.net>,
        Masahiro Yamada <masahiroy@kernel.org>,
        Linux Doc Mailing List <linux-doc@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>,
        clang-built-linux <clang-built-linux@googlegroups.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Jarmo Tiitto <jarmo.tiitto@gmail.com>
Subject: Re: [PATCH] pgo: rename the raw profile file to vmlinux.profraw
Message-ID: <202106011210.B5A8881214@keescook>
References: <20210531202044.426578-1-morbo@google.com>
 <e22afde4-e312-4589-cf2e-3c35219d7249@kernel.org>
 <CAGG=3QVdXxLf0T9+n9FidrRcfdWY36m-i=4kPRJjOojWhjiywg@mail.gmail.com>
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On Tue, Jun 01, 2021 at 01:24:39AM -0700, 'Bill Wendling' via Clang Built Linux wrote:
> On Mon, May 31, 2021 at 1:29 PM Nathan Chancellor <nathan@kernel.org> wrote:
> >
> > On 5/31/2021 1:20 PM, Bill Wendling wrote:
> > > Future PGO features may create other files in /sys/kernel/debug/pgo. So
> > > rename the kernel's raw profile data file to "vmlinux.profraw" to make
> > > which part of the kernel the file is for more explicit.
> > >
> > > Note that future files in /sys/kernel/debug/pgo should follow a similar
> > > naming convention.
> > >
> > > Signed-off-by: Bill Wendling <morbo@google.com>
> >
> > Guess this clears up my confusion around the module patches :)
> >
> To clarify, Jarmo did those patches on his own. I just wanted to
> clarify the naming convention. :-)

Is the expectation that there would be 1 file per module in
/sys/kernel/debug/pgo/ after the modules patch?

> 
> -bw
> 
> > Reviewed-by: Nathan Chancellor <nathan@kernel.org>
> >
> > > ---
> > >   Documentation/dev-tools/pgo.rst | 6 +++---
> > >   kernel/pgo/Kconfig              | 7 ++++---
> > >   kernel/pgo/fs.c                 | 2 +-
> > >   3 files changed, 8 insertions(+), 7 deletions(-)
> > >
> > > diff --git a/Documentation/dev-tools/pgo.rst b/Documentation/dev-tools/pgo.rst
> > > index b7f11d8405b7..0200449c4843 100644
> > > --- a/Documentation/dev-tools/pgo.rst
> > > +++ b/Documentation/dev-tools/pgo.rst
> > > @@ -76,7 +76,7 @@ The PGO kernel support creates the following files in debugfs:
> > >   ``/sys/kernel/debug/pgo/reset``
> > >       Global reset file: resets all coverage data to zero when written to.
> > >
> > > -``/sys/kernel/debug/profraw``
> > > +``/sys/kernel/debug/pgo/vmlinux.profraw``
> > >       The raw PGO data that must be processed with ``llvm_profdata``.
> > >
> > >
> > > @@ -108,7 +108,7 @@ using the result to optimize the kernel:
> > >
> > >      .. code-block:: sh
> > >
> > > -      $ cp -a /sys/kernel/debug/pgo/profraw /tmp/vmlinux.profraw
> > > +      $ cp -a /sys/kernel/debug/pgo/vmlinux.profraw /tmp/vmlinux.profraw

And if so, these instructions would change (in the future) to something
like:

     $ cp -a /sys/kernel/debug/pgo/*.profraw /tmp/prof/

?

-Kees

-- 
Kees Cook