Re: [PATCH 2/2] drm/hyperv: During panic do VMBus unload after frame buffer is flushed

[Jocelyn Falempe <jfalempe@redhat.com>]

On 12/02/2026 10:49, Jocelyn Falempe wrote:
> On 12/02/2026 00:01, mhklkml@zohomail.com wrote:
>> From: Jocelyn Falempe <jfalempe@redhat.com> Sent: Wednesday, February 
>> 11, 2026 1:54 PM
>>
>> But for this patch, the issue is that drm_panic() never gets called if 
>> CONFIG_PRINTK
>> isn't set. In that case, kmsg_dump_register() is a stub that returns 
>> an error.  So
>> drm_panic_register() never registers the callback to drm_panic(). And if
>> drm_panic() isn't going to run, responsibility for doing the VMBus unload
>> must remain with the VMBus code. It's hard to actually test this case 
>> because
>> of depending on printk() for debugging output, so double-check my
>> thinking.
> 
> Ok you're right. I changed from 
> atomic_notifier_chain_register(&panic_notifier_list, ...) to 
> kmsg_dump_register() in the v10 of drm_panic.
> 
> So I should either make DRM_PANIC depends on PRINTK, or call 
> atomic_notifier_chain_register() if PRINTK is not defined.
> 
> As I think kernel without PRINTK are uncommon, I'll probably do the 
> first solution.
> 

FYI, I just sent the corresponding change:

https://patchwork.freedesktop.org/series/161544/

Best regards,

--

Jocelyn