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From:   Dmitry Vyukov <dvyukov@google.com>
Date:   Thu, 27 Jan 2022 17:34:37 +0100
Message-ID: <CACT4Y+bLWWkZFd7iU6P1hWoF0Yp+9hDEo=puH4BfyETEmR7OMw@mail.gmail.com>
Subject: Re: [PATCH v1 0/4] fbtft: Unorphan the driver for maintenance
To:     Dmitry Vyukov <dvyukov@google.com>,
        Dan Carpenter <dan.carpenter@oracle.com>,
        syzkaller-bugs <syzkaller-bugs@googlegroups.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Andy Shevchenko <andy@kernel.org>, linux-fbdev@vger.kernel.org,
        Michael Hennerich <michael.hennerich@analog.com>,
        Helge Deller <deller@gmx.de>, linux-staging@lists.linux.dev,
        Javier Martinez Canillas <javierm@redhat.com>,
        dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org,
        Andy Shevchenko <andy.shevchenko@gmail.com>,
        Thomas Zimmermann <tzimmermann@suse.de>,
        Carlis <zhangxuezhi1@yulong.com>,
        Phillip Potter <phil@philpotter.co.uk>,
        Lee Jones <lee.jones@linaro.org>,
        Heiner Kallweit <hkallweit1@gmail.com>,
        syzkaller <syzkaller@googlegroups.com>
Cc:     Daniel Vetter <daniel@ffwll.ch>
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On Thu, 27 Jan 2022 at 12:11, Daniel Vetter <daniel@ffwll.ch> wrote:
>
> On Thu, Jan 27, 2022 at 11:32:58AM +0100, Dmitry Vyukov wrote:
> > On Thu, 27 Jan 2022 at 07:30, Dan Carpenter <dan.carpenter@oracle.com> wrote:
> > >
> > > On Wed, Jan 26, 2022 at 11:31:02PM +0100, Daniel Vetter wrote:
> > > > dOn Wed, Jan 26, 2022 at 3:46 PM Dan Carpenter <dan.carpenter@oracle.com> wrote:
> > > > >
> > > > > The other advantage of staging is the I don't think syzbot enables it.
> > > > > I guess it's easier to persuade Dmitry to ignore STAGING than it was to
> > > > > get him to disable FBDEV.  :P
> > > > >
> > > > > The memory corruption in fbdev was a real headache for everyone because
> > > > > the stack traces ended up all over the kernel.
> > > >
> > > > Uh Dmitry disabled all of FBDEV?
> > >
> > > No that's the opposite of what I meant.  STAGING is disabled in syzbot
> > > and FBDEV is enabled.
> >
> > Is there still any problem with syzbot config?
> > syzbot configs are stored here:
> > https://github.com/google/syzkaller/tree/master/dashboard/config/linux
>
> CONFIG_FB and CONFIG_FRAMEBUFFER_CONSOLE are set, which are the things I
> care about. The one exception is upstream-kcsan.config, which doesn't have
> fbcon enabled.
>
> Also looking through your fbdev drivers, really the only ones you want to
> ever enable are:
> CONFIG_FB_VGA16=y
> CONFIG_FB_VESA=y
> CONFIG_FB_VIRTUAL=y
>
> The following isn't enabled, but I guess if you don't have EFI doesn't
> make sense, otherwise you really want it:
> CONFIG_FB_EFI=y
>
> The below are enabled in some configs and should be ditched
> CONFIG_FB_SIMPLE=y (use CONFIG_DRM_SIMPLEDRM instead, at least on kernels that have it)
> CONFIG_FB_I740=y (you don't have this hw or I'm blown away, this last shipped 20 years ago)
> CONFIG_FB_UDL=y (use CONFIG_DRM_UDL instead)
> CONFIG_FB_UVESA=y (does modesets by calling into a userspace helper to run x86 vbios code, just don't)
> CONFIG_FB_SMSCUFX=y (if you really have these then someone should port this to drm asap)
> CONFIG_FB_CIRRUS=y (use CONFIG_DRM_CIRRUS_QEMU instead since I'm pretty sure you don't have a real cirrus pci card)
>
> Also note that the simpledrm driver will eat all the firmware fbdev
> drivers and unload them. So you need to run two configs to really cover
> both sets of drivers in all cases.

Thanks!

I've sent PR to update these configs as you suggest:
https://github.com/google/syzkaller/pull/2993