Message-ID: <dm22fmz6yuxrn7cwsviwg6djnbbwr2lq7aamatz3rjeeqf7r2q@mdmnolrb3ytq>
Date: Mon, 8 Sep 2025 23:58:17 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
To: Ryan Eatmon <reatmon@...com>
Cc: rob.clark@....qualcomm.com, Rob Clark <robdclark@...il.com>,
        Viswanath Kraleti <viswanath.kraleti@....qualcomm.com>,
        Abhinav Kumar <quic_abhinavk@...cinc.com>, Sean Paul <sean@...rly.run>,
        Marijn Suijten <marijn.suijten@...ainline.org>,
        David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>,
        linux-arm-msm@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        freedreno@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        Bruce Ashfield <bruce.ashfield@...il.com>
Subject: Re: [PATCH v2] drivers: gpu: drm: msm: registers: improve
 reproducibility

On Mon, Sep 08, 2025 at 12:59:37PM -0500, Ryan Eatmon wrote:
> 
> 
> On 9/8/2025 9:19 AM, Rob Clark wrote:
> > On Mon, Sep 8, 2025 at 6:39 AM Ryan Eatmon <reatmon@...com> wrote:
> > > 
> > > 
> > > 
> > > On 9/6/2025 6:24 PM, Rob Clark wrote:
> > > > On Sat, May 24, 2025 at 10:15 AM Dmitry Baryshkov
> > > > <dmitry.baryshkov@....qualcomm.com> wrote:
> > > > > 
> > > > > On Sat, May 24, 2025 at 09:25:37PM +0530, Viswanath Kraleti wrote:
> > > > > > From: Ryan Eatmon <reatmon@...com>
> > > > > > 
> > > > > > The files generated by gen_header.py capture the source path to the
> > > > > > input files and the date.  While that can be informative, it varies
> > > > > > based on where and when the kernel was built as the full path is
> > > > > > captured.
> > > > > > 
> > > > > > Since all of the files that this tool is run on is under the drivers
> > > > > > directory, this modifies the application to strip all of the path before
> > > > > > drivers.  Additionally it prints <stripped> instead of the date.
> > > > > > 
> > > > > > Signed-off-by: Ryan Eatmon <reatmon@...com>
> > > > > > Signed-off-by: Bruce Ashfield <bruce.ashfield@...il.com>
> > > > > > Signed-off-by: Viswanath Kraleti <viswanath.kraleti@....qualcomm.com>
> > > > > > ---
> > > > > > The files generated by gen_header.py include the source path to the
> > > > > > input files and the build date. While this information can be useful,
> > > > > > it inadvertently exposes build system configuration details in the
> > > > > > binaries. This hinders binary reproducibility, as the output will
> > > > > > vary if the build environment changes.
> > > > > > 
> > > > > > This change was originally submitted to the linux-yocto-dev kernel [1]
> > > > > > to address binary reproducibility QA errors. However, the fix is generic
> > > > > > enough to be applicable to the mainline kernel and would benefit other
> > > > > > distributions as well. So proposing it here for broader inclusion.
> > > > > > 
> > > > > > [1] https://git.yoctoproject.org/linux-yocto-dev/commit/?id=f36faf0f9f8d8f5b4c43a68e5c6bd83a62253140
> > > > > > ---
> > > > > > Changes in v2:
> > > > > > - Corrected author id
> > > > > > - Link to v1: https://lore.kernel.org/r/20250523-binrep-v1-1-c3a446518847@oss.qualcomm.com
> > > > > > ---
> > > > > >    drivers/gpu/drm/msm/registers/gen_header.py | 8 +++++---
> > > > > >    1 file changed, 5 insertions(+), 3 deletions(-)
> > > > > > 
> > > > > 
> > > > > Acked-by: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
> > > > > 
> > > > > Rob, WDYT?
> > > > 
> > > > I'm revisiting this one, in the context of trying to re-sync
> > > > gen_header.py with mesa.. but it is only changing the contents of
> > > > comments, so it's not quite clear to me how this ends up mattering for
> > > > binary reproducibility.
> > > 
> > > The reason it matters is that for Yocto, the generated header file is
> > > identified as a file that needs to be installed into the sysroot.  All
> > > files going into the sysroot are checked to make sure they do not
> > > contain dates and/or paths to the build directory contained within.
> > > Since this is a generated header file that is included in the sysroot we
> > > needed to strip out the path and date.
> > > 
> > > The idea for the reproducible builds are that the same files on a
> > > different a machine at a different time should produce 100% identical
> > > files.  Including paths and dates violates that tenet.
> > > 
> > > Hope that helps explain why we needed this.  So long as the
> > > gen_header.py is being called to generate header files then we need to
> > > maintain the reproducible aspect.
> > > 
> > 
> > My plan is (was?) to just replace the entire comment header with simply:
> > 
> >    /* Autogenerated file, DO NOT EDIT manually! */
> > 
> > That said, I'm not entirely sure why these files should get installed
> > into the sysroot?  I'm not super hands-on familiar with Yocto, so
> > maybe there is a good reason.. but if there is, maybe the plan to
> > remove the license/etc from the comment header isn't such a good idea
> > after all?
> 
> The generated header files would be part of a linux-headers package that
> would be needed to build other packages as part of the distro.  And so the
> header files are all checked against the rules.  A linux-headers type
> package is common for distros to have available.

I think you mean linux-libc-headers here. No, as Rob wrote, it is not
(these headers are not even under include/ subdir.

Do we check the work-shared/kernel-source and kernel-build-artifacts for
sysroot paths?

> 
> 
> > BR,
> > -R
> > 
> > > 
> > > > That said, since the generated files are no longer checked in to mesa
> > > > or the kernel, we could probably just drop all of this if it mattered.
> > > > 
> > > > BR,
> > > > -R
> > > 
> > > --
> > > Ryan Eatmon                reatmon@...com
> > > -----------------------------------------
> > > Texas Instruments, Inc.  -  LCPD  -  MGTS
> > > 
> > > 
> 
> -- 
> Ryan Eatmon                reatmon@...com
> -----------------------------------------
> Texas Instruments, Inc.  -  LCPD  -  MGTS
> 

-- 
With best wishes
Dmitry

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