linux-kernel - Re: [PATCH v6 3/5] fbdev: Disable sysfb device registration when removing conflicting FBs

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Message-ID: <aa144e20-a555-5c30-4796-09713c12ab0e@redhat.com>
Date:   Fri, 17 Jun 2022 08:46:18 +0200
From:   Javier Martinez Canillas <javierm@...hat.com>
To:     Zack Rusin <zackr@...are.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Cc:     "linux-fbdev@...r.kernel.org" <linux-fbdev@...r.kernel.org>,
        "kraxel@...hat.com" <kraxel@...hat.com>,
        "tzimmermann@...e.de" <tzimmermann@...e.de>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        "alex.williamson@...hat.com" <alex.williamson@...hat.com>,
        "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
        "daniel.vetter@...ll.ch" <daniel.vetter@...ll.ch>,
        "lersek@...hat.com" <lersek@...hat.com>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "deller@....de" <deller@....de>,
        Linux-graphics-maintainer <Linux-graphics-maintainer@...are.com>
Subject: Re: [PATCH v6 3/5] fbdev: Disable sysfb device registration when
 removing conflicting FBs

Hello Zack,

On 6/17/22 03:35, Zack Rusin wrote:
> On Fri, 2022-06-17 at 01:21 +0200, Javier Martinez Canillas wrote:
>> On 6/17/22 00:18, Javier Martinez Canillas wrote:
>>> On 6/16/22 23:03, Zack Rusin wrote:
>>
>> [snip]
>>
>>>
>>> I'll look at this tomorrow but in the meantime, could you please look if the following
>>> commits on top of drm-misc-next help ?
>>>
>>> d258d00fb9c7 fbdev: efifb: Cleanup fb_info in .fb_destroy rather than .remove
>>> 1b5853dfab7f fbdev: efifb: Fix a use-after-free due early fb_info cleanup
>>>
>>
>> Scratch that. I see in your config now that you are not using efifb but instead
>> simpledrm: CONFIG_DRM_SIMPLEDRM=y, CONFIG_SYSFB_SIMPLEFB=y and CONFIG_DRM_VMWGFX.
>>
>> Since you mentioned efifb I misunderstood that you are using it. Anyways, as
>> said I'll investigate this tomorrow.
> 
> Sounds good. Let me know if you'd like me to try it without SIMPLEFB.
>

Yes, please do. Either with CONFIG_SYSFB_SIMPLEFB disabled and CONFIG_FB_EFI
enabled (so that "efi-framebuffer" is registered and efifb probed) or with
CONFIG_SYSFB_SIMPLEFB but CONFIG_FB_SIMPLE enabled (so "simple-framebuffer
is used too but with simplefb instead of simpledrm).
 
I'm not able to reproduce, it would be useful to have another data point.

-- 
Best regards,

Javier Martinez Canillas
Linux Engineering
Red Hat