Re: bochs_drm: failed bochs_hw_init() results in panic - Marek Marczykowski-Górecki

From: "Marek Marczykowski-Górecki" <marmarek@invisiblethingslab.com>
To: Gerd Hoffmann <kraxel@redhat.com>
Cc: virtualization@lists.linux-foundation.org
Subject: Re: bochs_drm: failed bochs_hw_init() results in panic
Date: Sat, 11 Jan 2020 01:07:45 +0100	[thread overview]
Message-ID: <20200111000745.GF2507@mail-itl> (raw)
In-Reply-To: <20200110053553.4gqlagjdpfi6pg3b@sirius.home.kraxel.org>

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On Fri, Jan 10, 2020 at 06:35:53AM +0100, Gerd Hoffmann wrote:
> On Fri, Jan 10, 2020 at 02:33:28AM +0100, Marek Marczykowski-Górecki wrote:
> > Hi,
> > 
> > It looks like bochs_kms_fini() don't like being called if
> > bochs_kms_init() wasn't. Regardless of the reason for the
> > bochs_hw_init() failure (that's another story), it shouldn't cause a
> > panic. Any idea how to fix it?
> 
> maybe this?

Yes, it prevents the panic, with a little fix. Thanks!
Of course(?) I don't have working framebuffer then, but I can interact
with the system in other ways, at least to diagnose what's wrong.

Now the messages looks like this:

[   29.800835] bochs-drm 0000:00:02.0: remove_conflicting_pci_framebuffers: bar 0: 0xc0000000 -> 0xc0ffffff
[   29.800840] bochs-drm 0000:00:02.0: remove_conflicting_pci_framebuffers: bar 2: 0xc1087000 -> 0xc1087fff
[   29.800842] checking generic (c0000000 1000000) vs hw (c0000000 1000000)
[   29.800843] fb0: switching to bochsdrmfb from EFI VGA
[   29.805542] bochs-drm 0000:00:02.0: vgaarb: deactivate vga console
[   29.805742] bochs-drm 0000:00:02.0: BAR 0: can't reserve [mem 0xc0000000-0xc0ffffff pref]
[   29.805749] [drm:bochs_hw_init [bochs_drm]] *ERROR* Cannot request framebuffer
[   29.805781] bochs-drm: probe of 0000:00:02.0 failed with error -16
[   30.129014] Trying to free nonexistent resource <00000000c0000000-00000000c0ffffff>

Is the last one an issue?

> diff --git a/drivers/gpu/drm/bochs/bochs_kms.c b/drivers/gpu/drm/bochs/bochs_kms.c
> index 3f0006c2470d..322be68a238a 100644
> --- a/drivers/gpu/drm/bochs/bochs_kms.c
> +++ b/drivers/gpu/drm/bochs/bochs_kms.c
> @@ -192,6 +192,9 @@ int bochs_kms_init(struct bochs_device *bochs)
>  
>  void bochs_kms_fini(struct bochs_device *bochs)
>  {
> +	if (!dev->mode_config.num_connector)

bochs->dev->...

> +		return;
> +
>  	drm_atomic_helper_shutdown(bochs->dev);
>  	drm_mode_config_cleanup(bochs->dev);
>  }
> 

-- 
Best Regards,
Marek Marczykowski-Górecki
Invisible Things Lab
A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?

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